Patent Application
20190237748
The present invention relates generally to energy storage devices, and specifically to materials and methods for dry electrode energy storage devices having improved performance.
Electrical energy storage cells are widely used to provide power to electronic, electromechanical, electrochemical, and other useful devices. Such cells include batteries such as primary chemical cells and secondary (rechargeable) cells, fuel cells, and various species of capacitors, including ultracapacitors. Increasing the operating power and energy of energy storage devices, including capacitors and batteries, would be desirable for enhancing energy storage, increasing power capability, and broadening real-world use cases.
Energy storage devices including electrode films combining complimentary attributes may increase energy storage device performance in real-world applications. Furthermore, existing methods of fabrication may impose a practical limit to various structural electrode properties. Thus, new electrode film formulations, and methods for their fabrication, may result in improved performance. Additionally, novel combinations of electrode films may reveal combinations that provide improved performance to an energy storage device.
For purposes of summarizing the disclosure and the advantages achieved over the prior art, certain objects and advantages of the disclosure are described herein. Not all such objects or advantages may be achieved in any particular embodiment. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
In a first aspect, a lithium ion battery including at least one self-supporting dry electrode film and having enhanced performance is provided. The enhanced performance may be enhanced electrode material loading, active material loading, areal capacity, specific capacity, areal energy density, energy density, specific energy density, or Coulombic efficiency. In some embodiment, such batteries may have a specific energy density of at least 250 Wh/kg, or an energy density of at least 600 Wh/L.
In one aspect a single dry electrode film of an energy storage device is provided. The dry electrode film includes a dry active material. The dry electrode film further includes a dry binder. The dry electrode film further includes wherein the dry electrode film is free-standing, and wherein the dry electrode film is greater than about 110 μm in thickness.
In another aspect a dry electrode film of an energy storage device is provided. The dry electrode film includes a dry active material. The dry electrode film further includes a dry binder. The dry electrode film further includes wherein the dry electrode film is free-standing, and wherein the dry electrode film is at least 1.4 g/cm3 in electrode film density.
In another aspect a method is provided for fabricating a single dry electrode film of an energy storage device. The method includes providing a dry active material. The method further includes providing a dry binder. The method further includes combining the dry active material and dry binder to provide an electrode film mixture. The method further includes forming a free-standing dry electrode film with a thickness of greater than about 110 μm from the electrode film mixture.
In another aspect a method is provided for fabricating a dry electrode film of an energy storage device. The method includes providing a dry active material. The method further includes providing a dry binder. The method further includes combining the dry active material and dry binder to provide an electrode film mixture. The method further includes forming a free-standing dry electrode film with an electrode film density of at least 1.4 g/cm3 from the electrode film mixture.
All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed.
Provided herein are various embodiments of energy storage devices having improved performance. In particular, in certain embodiments, energy storage devices disclosed herein include electrode films having high energy density. The energy storage devices incorporate electrode films fabricated using improved techniques, and by combinations of various processes. The energy storage devices may be lithium ion based batteries.
Lithium ion batteries have been relied on as a power source in numerous commercial and industrial uses, for example, in consumer devices, productivity devices, and in battery powered vehicles. However, demands placed on energy storage devices are continuously—and rapidly—growing. For example, the automotive industry is developing vehicles that rely on compact and efficient energy storage, such as plug-in hybrid vehicles and pure electric vehicles. Lithium ion batteries are well suited to meet future demands however improvements in energy density are needed to provide longer life batteries that can travel further on a single charge. Thus, there is a need for energy storage devices in general, and lithium ion batteries in particular, capable of providing higher energy storage or density per size relative to, for example, the mass and/or volume of the device.
Key components of the storage potential of an energy storage device are the electrodes, and more specifically, the electrode films comprising each electrode. The electrochemical capabilities of electrodes, for example, the capacity and efficiency of battery electrodes, is governed by various factors. For example, distribution of active material, binder and additive(s); the physical properties of materials therein, such as particle size and surface area of active material; the surface properties of the active materials; and the physical characteristics of the electrode film, such as cohesiveness, and adhesiveness to a conductive element.
In principle, a thicker electrode film is advantageous because, as the electrode film gets thicker, more active materials are present relative to other, non-energy-storing components, of a device. A thicker electrode film may be realized as loading of electrode materials per unit area of a current collector, or alternatively as capacity or energy density per unit area of electrode film. However, thicker electrode films test the practical limits of electrode film fabrication techniques.
Generally, electrode films may suffer reduced performance due to the mechanical properties of the film components, and interactions therebetween. For example, it is thought that mechanical limitations may result from poor adhesion between an active layer and a current collector, and poor cohesion in the electrode film, for example, between active materials and binders. Such processes may lead to losses in performance in both power delivery and energy storage capacity. It is thought that losses in performance may be due to deactivation of active materials, for example, due to losses in ionic conductivity, in electrical conductivity, or a combination thereof. For example, as adhesion between active layers and current collectors decrease, cell resistance may increase. Decreases in cohesion between active materials may also lead to increases in cell resistance, and in some cases electrical contact may be lost, removing some active material from the ionic and electrical transfer cycles in the cell. Without being limited by theory, it is thought that volumetric changes in the active materials may contribute to such processes. For example, additional degradation may be observed in electrodes incorporating certain active materials, such as silicon-based materials, that undergo significant volumetric changes during cell cycling. Lithium intercalation-deintercalation processes may correspond to such volumetric changes in some systems. Generally, these mechanical degradation processes may be observed in any electrode, for example a cathode, an anode, a positive electrode, a negative electrode, a battery electrode, a capacitor electrode, a hybrid electrode, or other energy storage device electrode.
Classical slurry coated wet battery electrodes suffer from some undesired issues such as cracking, delamination and poor flexibility, which are exacerbated in thicker electrode films. As an electrode film gets thicker, which generally corresponds to higher electrode material loading, loss of electrochemical performance and reliability may be observed in wet processed electrodes. Wet processes may suffer from limited material choice, and the resulting wet processed electrode films may also suffer from a non-uniform dispersion of constituent materials, for example, active materials. The non-uniformity may be exacerbated as film thickness and/or density is increased, and may result in poor ionic and/or electrical conductivity. Wet processes also generally require expensive and time-consuming drying steps, which become more difficult as the film becomes thicker. Thus, the thickness of an electrode film produced by a wet process may also be limited. Furthermore, in wet, for example, slurry-based, film-forming processing such as spraying, chemical bath deposition, slot die, extrusion, and printing, the possible configurations of electrode films may be limited.
Embodiments include batteries including an electrode made by a dry process that have a specific energy density of at least 250 Wh/kg, or an energy density of at least 600 Wh/L. Embodiments include dry electrode formulations and fabrication processes that achieve electrode films having a higher density of active materials, a greater electrode film thickness, a higher electrode film density, and/or a higher electronic density (for example, such as energy density, specific energy density, areal energy density, areal capacity and/or specific capacity). An electrode film with a higher electrode film density will generally include more active materials in a smaller electrode film volume. Specifically, smaller particle sizes and more intimate contact of active materials, binders, and additives may be realized in dry electrode processing. Dry electrode processing methods traditionally used a high shear and/or high pressure processing step to break up and commingle electrode film materials, which may contribute to the structural advantages. In some embodiments, such dry electrode processes may enable electrode films with substantially higher electrode densities (about 1.55 g/cm3) and lower electrode porosities (about 26%) with high loadings compared to conventional wet slurry cast and compressed electrode process densities (about 1.3 g/cm3 or less) and porosities (about 37% or more). However, as seen in
A dry or self-supporting electrode film as provided herein may provide improved characteristics relative to a typical electrode film. For example, a dry or self-supporting electrode film as provided herein may provide one or more of improved material loading or electrode material loading (which may be expressed as mass of electrode film per unit area of electrode film or current collector), improved active material loading (which may be expressed as mass of active material per unit area of electrode film or current collector), improved areal capacity (which may be expressed as capacity per unit area of electrode film or current collector), improved areal energy density (which may be expressed as energy per unit area of electrode film or current collector), improved specific energy density (which may be expressed as energy per unit mass of electrode film), or improved energy density (which may be expressed as energy per unit volume of electrode film). For further example, a dry or self-supporting electrode film as provided herein may provide improved Coulombic efficiency.
Some embodiments provide an energy storage device exhibiting improved Coulombic efficiency relative to an energy storage device constructed using typical materials and fabrication processes. In particular, the first cycle efficiency of a lithium ion battery including at least one dry process and/or self-supporting electrode as provided herein may be improved. For example, first cycle columbic efficiency during electrochemical cycling may be improved.
An energy storage device described herein may advantageously be characterized by reduced rise in equivalent series resistance over the life of the device, which may provide a device with increased power density over the life of the device. In some embodiments, energy storage devices described herein may be characterized by reduced loss of capacity over the life of the device. Further improvements that may be realized in various embodiments include improved cycling performance, including improved storage stability during cycling, and reduced capacity fade.
In some embodiments, dry process battery electrodes may be coupled with conventional slurry coated wet battery electrodes to provide improved performance of batteries including a dry electrode. In particular, in some embodiments the improved performance of the self-supporting dry cathode, wet anode pair may be realized.
In some embodiments, an energy storage device, such as a lithium ion battery, includes a cathode comprising a self-supporting dry electrode film, and an anode comprising a self-supporting dry electrode film, wherein the energy storage device has one or more additional characteristics provided herein. In further embodiments, an energy storage device includes a cathode comprising a self-supporting dry electrode film, and wherein the energy storage device has one or more other performance characteristics provided herein. In still further embodiments, an energy storage device, such as a lithium ion battery, includes a cathode comprising a self-supporting dry electrode film, and an anode comprising a wet process electrode film, wherein the energy storage device has one or more additional performance characteristics provided herein. Several combinations of wet and dry electrodes can be envisioned, as seen in Table 1.
Wherein in Table 1, “Dry” refers to a self-supporting electrode film (having the composition of an anode or cathode as indicated) prepared by a dry process, and “Wet” refers to an electrode film (having the composition of an anode or cathode as indicated) prepared by a slurry process.
Some embodiments relate to dry electrode processing techniques. In one embodiment, dry powder mixing conditions (i.e. sequence, intensity and time), mixing methods such as grinding and milling, and formulation development (i.e. active material, additive, binder) have resulted in improved electrochemical performance of the resulting dry battery electrode. Improvement may be realized relative to conventional dry electrode fabrication processes, as disclosed in one or more of U.S. Publication No. 2006/0114643, U.S. Publication No. 2006/0133013, U.S. Pat. No. 9,525,168, or 7,935,155, each of which is incorporated by reference herein in the entirety.
In various embodiments, a dry powder can be mixed by a mild process using, for example a convection, pneumatic or diffusion mixer as follows: a tumbler with and without mixing media (for example, glass bead, ceramic ball), a paddle mixer, a blade blender or an acoustic mixer. The mild mixing process may be nondestructive with respect to any active materials in the mixture. Without limitation, graphite particles may be preserved of size following the mild mixing process. In further embodiments, the powder mixing sequence and conditions can be varied to improve uniform distribution of active material, binder, and optional additive(s).
Embodiments include electrode films fabricated by various combinations of electrode film processing methods. Some examples of electrode formulation that consists of processed active material and binder are listed in the Table 2. Process A includes mild powder processing such as for example, tumbling, blending, or acoustic mixing, and Process B includes intense powder processing such as in a Waring blender, by jet milling or by grinding.
The materials and methods provided herein can be implemented in various energy storage devices. As provided herein, an energy storage device can be a capacitor, a lithium ion capacitor (LIC), an ultracapacitor, a battery, or a hybrid energy storage device combining aspects of two or more of the foregoing. In preferable embodiments, the device is a battery.
An energy storage device as provided herein can be of any suitable configuration, for example planar, spirally wound, button shaped, or pouch. An energy storage device as provided herein can be a component of a system, for example, a power generation system, an uninterruptible power source systems (UPS), a photo voltaic power generation system, an energy recovery system for use in, for example, industrial machinery and/or transportation. An energy storage device as provided herein may be used to power various electronic device and/or motor vehicles, including hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and/or electric vehicles (EV).
The device has a first electrode 102, a second electrode 104, and a separator 106 positioned between the first electrode 102 and second electrode 104. The first electrode 102 and the second electrode 104 are adjacent to respective opposing surfaces of the separator 106. The energy storage device 100 includes an electrolyte 118 to facilitate ionic communication between the electrodes 102, 104 of the energy storage device 100. For example, the electrolyte 118 may be in contact with the first electrode 102, the second electrode 104 and the separator 106. The electrolyte 118, the first electrode 102, the second electrode 104, and the separator 106 are housed within an energy storage device housing 120.
One or more of the first electrode 102, the second electrode 104, and the separator 106, or constituent thereof, may comprise porous material. The pores within the porous material can provide containment for and/or increased surface area for contact with an electrolyte 118 within the housing 120. The energy storage device housing 120 may be sealed around the first electrode 102, the second electrode 104 and the separator 106, and may be physically sealed from the surrounding environment.
In some embodiments, the first electrode 102 can be an anode (the “negative electrode”) and the second electrode 104 can be the cathode (the “positive electrode”). The separator 106 can be configured to electrically insulate two electrodes adjacent to opposing sides of the separator 106, such as the first electrode 102 and the second electrode 104, while permitting ionic communication between the two adjacent electrodes. The separator 106 can comprise a suitable porous, electrically insulating material. In some embodiments, the separator 106 can comprise a polymeric material. For example, the separator 106 can comprise a cellulosic material (e.g., paper), a polyethylene (PE) material, a polypropylene (PP) material, and/or a polyethylene and polypropylene material.
Generally, the first electrode 102 and second electrode 104 each comprise a current collector and an electrode film. Electrodes 102 and 104 comprise high density electrode films 112 and 114 with high electrode film densities and/or high electronic densities, respectively. Electrodes 102 and 104 each have a single electrode film 112 and 114 as shown, but other combinations with two or more electrode films for each electrode 102 and 104 are possible. Device 100 is shown with a single electrode 102 and a single electrode 104, but other combinations are possible. High density electrode films 112 and 114 can each have any suitable shape, size and thickness. For example, the electrode films can each have a thickness of about 30 microns (μm) to about 250 microns, for example, about, or at least about 50 microns, about 100 microns, about 150 microns, about 200 microns, about 250 microns, about 300 microns, about 400 microns, about 500 microns, about 750 microns, about 1000 microns, about 2000 microns, or any range of values therebetween. Further electrode film thicknesses are described throughout the disclosure, for a single electrode film. The electrode films generally comprise one or more active materials, for example, anode active materials or cathode active materials as provided herein. The electrode films 112 and/or 114 may be dry and/or self-supporting electrode films as provided herein, and having advantageous properties, such as thickness, increased electrode film density, energy density, specific energy density, areal energy density, areal capacity or specific capacity, as provided herein. The first electrode film 112 and/or the second electrode film 114 may also include one or more binders as provided herein. The electrode films 112 and/or 114 may be prepared by a process as described herein. The electrode films 112 and/or 114 may be wet or self-supporting dry electrodes as described herein.
As shown in
Various embodiments of electrode configurations, for example, of energy storage device 100, are presented in
Various battery cell configurations are depicted in
In some embodiments, the at least one active material includes a treated carbon material, where the treated carbon material includes a reduction in a number of hydrogen-containing functional groups, nitrogen-containing functional groups and/or oxygen-containing functional groups, as described in U.S. Patent Publication No. 2014/0098464. For example, the treated carbon particles can include a reduction in a number of one or more functional groups on one or more surfaces of the treated carbon, for example about 10% to about 60% reduction in one or more functional groups compared to an untreated carbon surface, including about 20% to about 50%. The treated carbon can include a reduced number of hydrogen-containing functional groups, nitrogen-containing functional groups, and/or oxygen-containing functional groups. In some embodiments, the treated carbon material comprises functional groups less than about 1% of which contain hydrogen, including less than about 0.5%. In some embodiments, the treated carbon material comprises functional groups less than about 0.5% of which contains nitrogen, including less than about 0.1%. In some embodiments, the treated carbon material comprises functional groups less than about 5% of which contains oxygen, including less than about 3%. In further embodiments, the treated carbon material comprises about 30% fewer hydrogen-containing functional groups than an untreated carbon material.
In some embodiments, energy storage device 100 can be a lithium ion battery. In some embodiments, the electrode film of a lithium ion battery electrode can comprise one or more active materials, and a fibrillized binder matrix as provided herein.
In further embodiments, the energy storage device 100 is charged with a suitable lithium-containing electrolyte. For example, device 100 can include a lithium salt, and a solvent, such as a non-aqueous or organic solvent. Generally, the lithium salt includes an anion that is redox stable. In some embodiments, the anion can be monovalent. In some embodiments, a lithium salt can be selected from hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium bis(trifluoromethansulfonyl)imide (LiN(SO2CF3)2), lithium trifluoromethansulfonate (LiSO3CF3), lithium bis(oxalate)borate (LiBOB) and combinations thereof. In some embodiments, the electrolyte can include a quaternary ammonium cation and an anion selected from the group consisting of hexafluorophosphate, tetrafluoroborate and iodide. In some embodiments, the salt concentration can be about 0.1 mol/L (M) to about 5 M, about 0.2 M to about 3 M, or about 0.3 M to about 2 M. In further embodiments, the salt concentration of the electrolyte can be about 0.7 M to about 1 M. In certain embodiments, the salt concentration of the electrolyte can be about 0.2 M, about 0.3 M, about 0.4 M, about 0.5 M, about 0.6 M, about 0.7 M, about 0.8 M, about 0.9 M, about 1 M, about 1.1 M, about 1.2 M, or any range of values therebetween.
In some embodiments, an energy storage device electrolyte as provided herein can include a liquid solvent. A solvent as provided herein need not dissolve every component, and need not completely dissolve any component, of the electrolyte. In further embodiments, the solvent can be an organic solvent. In some embodiments, a solvent can include one or more functional groups selected from carbonates, ethers and/or esters. In some embodiments, the solvent can comprise a carbonate. In further embodiments, the carbonate can be selected from cyclic carbonates such as, for example, ethylene carbonate (EC), propylene carbonate (PC), vinyl ethylene carbonate (VEC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and combinations thereof, or acyclic carbonates such as, for example, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and combinations thereof. In certain embodiments, the electrolyte can comprise LiPF6, and one or more carbonates.
In some embodiments, the lithium ion battery is configured to operate at about 2.5 to 4.5 V, or 3.0 to 4.2 V. In further embodiments, the lithium ion battery is configured to have a minimum operating voltage of about 2.5 V to about 3 V, respectively. In still further embodiments, the lithium ion battery is configured to have a maximum operating voltage of about 4.1 V to about 4.4 V, respectively.
In some embodiments, a method for fabricating an energy storage device is provided. In further embodiments, the method comprises selecting an anode and a cathode. In some embodiments, selecting the anode comprises selecting a dry self-supporting anode or a wet anode. In further embodiments, selecting the cathode comprises selecting a dry self-supporting cathode or a wet cathode. The step of selecting a dry anode may comprise selecting an active material processing method, and selecting a binder processing method.
In some embodiments, an electrode film as provided herein includes at least one active material and at least one binder. The at least one active material can be any active material known in the art. The at least one active material may be a material suitable for use in the anode or cathode of a battery. Anode active materials can comprise, for example, an insertion material (such as carbon, graphite, and/or graphene), an alloying/dealloying material (such as silicon, silicon oxide, tin, and/or tin oxide), a metal alloy or compound (such as Si—Al, and/or Si—Sn), and/or a conversion material (such as manganese oxide, molybdenum oxide, nickel oxide, and/or copper oxide). The anode active materials can be used alone or mixed together to form multi-phase materials (such as Si—C, Sn—C, SiOx—C, SnOx—C, Si—Sn, Si—SiOx, Sn—SnOx, Si—SiOx—C, Sn—SnOx—C, Si—Sn—C, SiOx—SnOx—C, Si—SiOx—Sn, or Sn—SiOx—SnOx).
The cathode active material, can comprise, for example, a metal oxide, metal sulfide, or a lithium metal oxide. The lithium metal oxide can be, for example, a lithium nickel manganese cobalt oxide (NMC), a lithium manganese oxide (LMO), a lithium iron phosphate (LFP), a lithium cobalt oxide (LCO), a lithium titanate (LTO), and/or a lithium nickel cobalt aluminum oxide (NCA). In some embodiments, cathode active materials can comprise, for example, a layered transition metal oxide (such as LiCoO2 (LCO), Li(NiMnCo)O2 (NMC) and/or LiNi0.8Co0.15Al0.05O2 (NCA)), a spinel manganese oxide (such as LiMn2O4 (LMO) and/or LiMn1.5Ni0.5O4 (LMNO)) or an olivine (such as LiFePO4). The cathode active material can comprise sulfur or a material including sulfur, such as lithium sulfide (Li2S), or other sulfur-based materials, or a mixture thereof. In some embodiments, the cathode film comprises a sulfur or a material including sulfur active material at a concentration of at least 50 wt %. In some embodiments, the cathode film comprising a sulfur or a material including sulfur active material has an areal capacity of at least 6 mAh/cm2. In some embodiments, the cathode film comprising a sulfur or a material including sulfur active material has an electrode film density of 1 g/cm3. In some embodiments, the cathode film comprising a sulfur or a material including sulfur active material further comprises a binder. In some embodiments, the binder of the cathode film comprising a sulfur or a material including sulfur active material is selected from polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene (PE), other thermoplastics, or any combination thereof.
The at least one active material may include one or more carbon materials. The carbon materials may be selected from, for example, graphitic material, graphite, graphene-containing materials, hard carbon, soft carbon, carbon nanotubes, porous carbon, conductive carbon, or a combination thereof. Activated carbon can be derived from a steam process or an acid/etching process. In some embodiments, the graphitic material can be a surface treated material. In some embodiments, the porous carbon can comprise activated carbon. In some embodiments, the porous carbon can comprise hierarchically structured carbon. In some embodiments, the porous carbon can include structured carbon nanotubes, structured carbon nanowires and/or structured carbon nanosheets. In some embodiments, the porous carbon can include graphene sheets. In some embodiments, the porous carbon can be a surface treated carbon.
In some embodiments, a cathode electrode film of a lithium ion battery or hybrid energy storage device can include about 70 weight % to about 98 weight % of the at least one active material, including about 70 weight % to about 92 weight %, or about 70 weight % to about 96 weight %. In some embodiments, a cathode electrode film can comprise about or up to about 70 weight %, about or up to about 90 weight %, about or up to about 92 weight %, about 94 weight %, about 95 weight %, about or up to about 96 weight % or about or up to about 98 weight % of the at least one active material, or any range of values therebetween. In some embodiments, a cathode electrode film of a lithium ion battery or hybrid energy storage device can include about 40 weight % to about 60 weight % of the at least one active material. In some embodiments, the cathode electrode film can comprise up to about 10 weight % of the porous carbon material, including up to about 5 weight %, or about 1 weight % to about 5 weight %. In some embodiments, the cathode electrode film can comprise about or up to about 10 weight %, about or up to about 5 weight %, about or up to about 1 weight % or about or up to about 0.5 weight % of the porous carbon material, or any range of values therebetween. In some embodiments, the cathode electrode film comprises up to about 5 weight %, including about 1 weight % to about 3 weight %, of the conductive additive. In some embodiments, the cathode electrode film comprises about or up to about 10 weight %, 5 weight %, about or up to about 3 weight % or about or up to about 1 weight % of the conductive additive, or any range of values therebetween. In some embodiments, the cathode electrode film comprises up to about 20 weight % of the binder, for example, about 1.5 weight % to 10 weight %, about 1.5 weight % to 5 weight %, or about 1.5 weight % to 3 weight %. In some embodiments, the cathode electrode film comprises about 1.5 weight % to about 3 weight % binder. In some embodiments, the cathode electrode film comprises about or up to about 20 weight %, about or up to about 15 weight %, about or up to about 10 weight %, about or up to about 5 weight %, about or up to about 3 weight %, about or up to about 1.5 weight % or about or up to about 1 weight % of the binder, or any range of values therebetween.
In some embodiments, an anode electrode film may comprise at least one active material, a binder, and optionally a conductive additive. In some embodiments, the conductive additive may comprise a conductive carbon additive, such as carbon black. In some embodiments, the at least one active material of the anode may comprise synthetic graphite, natural graphite, hard carbon, soft carbon, graphene, mesoporous carbon, silicon, silicon oxides, tin, tin oxides, germanium, lithium titanate, mixtures, or composites of the aforementioned materials. In some embodiments, an anode electrode film can include about 80 weight % to about 98 weight % of the at least one active material, including about 80 weight % to about 98 weight %, or about 94 weight % to about 97 weight %. In some embodiments, an anode electrode film can include about 80 weight %, about 85 weight %, about 90 weight %, about 92 weight %, about 94 weight %, about 95 weight %, about 96 weight %, about 97 weight % or about 98 weight % or about 99 weight % of the at least one active material, or any range of values therebetween. In some embodiments, the anode electrode film comprises up to about 5 weight %, including about 1 weight % to about 3 weight %, of the conductive additive. In some embodiments, the anode electrode film comprises about or up to about 5 weight %, about or up to about 3 weight %, about or up to about 1 weight % or about or up to about 0.5 weight % of the conductive additive, or any range of values therebetween. In some embodiments, the anode electrode film comprises up to about 20 weight % of the binder, including about 1.5 weight % to 10 weight %, about 1.5 weight % to 5 weight %, or about 3 weight % to 5 weight %. In some embodiments, the anode electrode film comprises about 4 weight % binder. In some embodiments, the anode electrode film comprises about or up to about 20 weight %, about or up to about 15 weight %, about or up to about 10 weight %, about or up to about 5 weight %, about or up to about 3 weight %, about or up to about 1.5 weight % or about or up to about 1 weight % of the binder, or any range of values therebetween. In some embodiments, the anode film may not include a conductive additive.
Some embodiments include an electrode film, such as of an anode and/or a cathode, having one or more active layers comprising a polymeric binder material. The binder can include polytetrafluoroethylene (PTFE), a polyolefin, polyalkylenes, polyethers, styrene-butadiene, co-polymers of polysiloxanes and polysiloxane, branched polyethers, polyvinylethers, co-polymers thereof, and/or admixtures thereof. The binder can include a cellulose, for example, carboxymethylcellulose (CMC). In some embodiments, the polyolefin can include polyethylene (PE), polypropylene (PP), polyvinylidene fluoride (PVDF), co-polymers thereof, and/or mixtures thereof. For example, the binder can include polyvinylene chloride, poly(phenylene oxide) (PPO), polyethylene-block-poly(ethylene glycol), poly(ethylene oxide) (PEO), poly(phenylene oxide) (PPO), polyethylene-block-poly(ethylene glycol), polydimethylsiloxane (PDMS), polydimethylsiloxane-coalkylmethylsiloxane, co-polymers thereof, and/or admixtures thereof. In some embodiments, the binder may be a thermoplastic. In some embodiments, the binder comprises a fibrillizable polymer. In certain embodiments, the binder comprises, consists essentially, or consists of PTFE.
In some embodiments, the binder may comprise PTFE and optionally one or more additional binder components. In some embodiments, the binder may comprise one or more polyolefins and/or co-polymers thereof, and PTFE. In some embodiments, the binder may comprise a PTFE and one or more of a cellulose, a polyolefin, a polyether, a precursor of polyether, a polysiloxane, co-polymers thereof, and/or admixtures thereof. An admixture of polymers may comprise interpenetrating networks of the aforementioned polymers or co-polymers.
The binder may include various suitable ratios of the polymeric components. For example, PTFE can be up to about 98 weight % of the binder, for example, from about 20 weight % to about 95 weight %, about 20 weight % to about 90 weight %, including about 20 weight % to about 80 weight %, about 30 weight % to about 70 weight %, about 30 weight % to about 50 weight %, or about 50 weight % to about 90 weight %. In some embodiments, PTFE can be about or up to about 99 weight %, about or up to about 98 weight %, about or up to about 95 weight %, about or up to about 90 weight %, about or up to about 80 weight %, about or up to about 70 weight %, about or up to about 60 weight %, about or up to about 50 weight %, about or up to about 40 weight %, about or up to about 30 weight % or about or up to about 20 weight % of the binder, or any range of values therebetween. In some embodiments, the binder can consistent essentially of or consist of PTFE.
In some embodiments, the electrode film mixture may include binder particles having selected sizes. In some embodiments, the binder particles may be about 50 nm, about 100 nm, about 150 nm, about 200 nm, about 250 nm, about 300 nm, about 350 nm, about 400 nm, about 450 nm, about 500 nm, about 1 μm, about 2 μm, about 3 μm, about 4 μm, about 5 μm, about 10 μm, about 50 μm, about 100 μm, or any range of values therebetween.
As used herein, a dry fabrication process can refer to a process in which no or substantially no solvents are used in the formation of an electrode film. For example, components of the active layer or electrode film, including carbon materials and binders, may comprise dry particles. The dry particles for forming the active layer or electrode film may be combined to provide a dry particle active layer mixture. In some embodiments, the active layer or electrode film may be formed from the dry particle active layer mixture such that weight percentages of the components of the active layer or electrode film and weight percentages of the components of the dry particles active layer mixture are substantially the same. In some embodiments, the active layer or electrode film formed from the dry particle active layer mixture using the dry fabrication process may be free from, or substantially free from, any processing additives such as solvents and solvent residues resulting therefrom. In some embodiments, the resulting active layer or electrode films are self-supporting films formed using the dry process from the dry particle mixture. In some embodiments, the resulting active layer or electrode films are free-standing films formed using the dry process from the dry particle mixture. A process for forming an active layer or electrode film can include fibrillizing the fibrillizable binder component(s) such that the film comprises fibrillized binder. In further embodiments, a free-standing active layer or electrode film may be formed in the absence of a current collector. In still further embodiments, an active layer or electrode film may comprise a fibrillized polymer matrix such that the film is self-supporting. It is thought that a matrix, lattice, or web of fibrils can be formed to provide mechanical structure to the electrode film.
In some embodiments, an energy storage device electrode film, wherein the electrode film is dry and/or self-supporting film, may provide a high electrode material loading, or a high active material loading (which may be expressed as mass of electrode film per unit area of electrode film or current collector) of about 12 mg/cm2, about 13 mg/cm2, about 14 mg/cm2, about 15 mg/cm2, about 16 mg/cm2, about 17 mg/cm2, about 18 mg/cm2, about 19 mg/cm2, about 20 mg/cm2, about 21 mg/cm2, about 22 mg/cm2, about 23 mg/cm2, about 24 mg/cm2, about 25 mg/cm2, about 26 mg/cm2, about 27 mg/cm2, about 28 mg/cm2, about 29 mg/cm2, about 30 mg/cm2, about 40 mg/cm2, about 50 mg/cm2, about 60 mg/cm2, about 70 mg/cm2, about 80 mg/cm2, about 90 mg/cm2 or about 100 mg/cm2, or any range of values therebetween. In some embodiments, an energy storage device electrode film, wherein the electrode film is dry and/or self-supporting film, may provide a high electrode material loading, or a high active material loading (which may be expressed as mass of electrode film per unit area of electrode film or current collector) of at least about 12 mg/cm2, at least about 13 mg/cm2, at least about 14 mg/cm2, at least about 15 mg/cm2, at least about 16 mg/cm2, at least about 17 mg/cm2, at least about 18 mg/cm2, at least about 19 mg/cm2, at least about 20 mg/cm2, at least about 21 mg/cm2, at least about 22 mg/cm2, at least about 23 mg/cm2, at least about 24 mg/cm2, at least about 25 mg/cm2, at least about 26 mg/cm2, at least about 27 mg/cm2, at least about 28 mg/cm2, at least about 29 mg/cm2, at least about 30 mg/cm2, at least about 40 mg/cm2, at least about 50 mg/cm2, at least about 60 mg/cm2, at least about 70 mg/cm2, at least about 80 mg/cm2, at least about 90 mg/cm2 or at least about 100 mg/cm2, or any range of values therebetween.
An electrode film may have a selected thickness suitable for certain applications. The thickness of an electrode film as provided herein may be greater than that of an electrode film prepared by conventional processes. In some embodiments, the electrode film can have a thickness of about, or greater than about, 110 microns, about 115 microns, about 120 microns, about 130 microns, about 135 microns, about 150 microns, about 155 microns, about 160 microns, about 170 microns, about 200 microns, about 250 microns, about 260 microns, about 265 microns, about 270 microns, about 280 microns, about 290 microns, about 300 microns, about 350 microns, about 400 microns, about 450 microns, about 500 microns, about 750 microns, about 1 mm, or about 2 mm, or any range of values therebetween. An electrode film thickness can be selected to correspond to a desired areal capacity, specific capacity, areal energy density, energy density, or specific energy density.
In some embodiments, the electrode film porosity of an electrode film as provided herein may be greater than that of an electrode film prepared by conventional processes. In some embodiments, the electrode film porosity of an electrode film as provided herein may be less than that of an electrode film prepared by conventional processes. In some embodiments, the electrode film can have an electrode film porosity (which may be expressed as the percentage of volume of electrode film occupied by pores) of about 10%, about 12%, about 14%, about 16%, about 18% or about 20%, or any range of values therebetween. In some embodiments, the electrode film can have an electrode film porosity (which may be expressed as the percentage of volume of electrode film occupied by pores) of at least about 10%, at least about 12%, at least about 14%, at least about 16%, at least about 18% or at least about 20%, or any range of values therebetween. In some embodiments, the electrode film can have an electrode film porosity (which may be expressed as the percentage of volume of electrode film occupied by pores) of at most about 10%, at most about 12%, at most about 14%, at most about 16%, at most about 18% or at most about 20%, or any range of values therebetween.
In some embodiments, the electrode film density of an electrode film as provided herein may be less than that of an electrode film prepared by conventional processes. In some embodiments, the electrode film density of an electrode film as provided herein may be greater than that of an electrode film prepared by conventional processes. In some embodiments, the electrode film can have an electrode film density of about 0.8 g/cm3, 1.0 g/cm3, 1.4 g/cm3, about 1.5 g/cm3, about 1.6 g/cm3, about 1.7 g/cm3, about 1.8 g/cm3, about 1.9 g/cm3, about 2.0 g/cm3, about 2.5 g/cm3, about 3.0 g/cm3, about 3.3 g/cm3, about 3.4 g/cm3, about 3.5 g/cm3, about 3.6 g/cm3, about 3.7 g/cm3 or about 3.8 g/cm3, or any range of values therebetween. In some embodiments, the electrode film can have an electrode film density of at most about 0.8 g/cm3, 1.0 g/cm3, 1.4 g/cm3, at most about 1.5 g/cm3, at most about 1.6 g/cm3, at most about 1.7 g/cm3, at most about 1.8 g/cm3, at most about 1.9 g/cm3 or at most about 2.0 g/cm3, or any range of values therebetween. In some embodiments, the electrode film can have density of at least about 0.8 g/cm3, 1.0 g/cm3, 1.4 g/cm3, at least about 1.5 g/cm3, at least about 1.6 g/cm3, at least about 1.7 g/cm3, at least about 1.8 g/cm3, at least about 1.9 g/cm3, at least about 2.0 g/cm3, at least about 2.5 g/cm3, at least about 3.0 g/cm3, at least about 3.3 g/cm3, at least about 3.4 g/cm3 or at least about 3.5 g/cm3, or any range of values therebetween.
The electrode formulation may be calendered into an electrode film as provided herein at temperatures lower than conventional processes. In some embodiments, the electrode formulation may be calendered at a temperature of about 20° C., about 23° C., about 25° C., about 30° C., about 35° C., about 40° C., about 50° C., about 60° C., about 65° C., about 90° C., about 120° C., about 150° C., about 170° C. or about 200° C., or any range of values therebetween. In some embodiments, the electrode formulation may be calendered at about ambient or room temperature.
In some embodiments, an energy storage device electrode film, wherein the electrode film is dry and/or self-supporting film, may provide areal capacity (which may be expressed as capacity per unit area of electrode film or current collector) of about, or at least about 3.5 mAh/cm2, about 3.8 mAh/cm2, about 4 mAh/cm2, about 4.3 mAh/cm2, about 4.5 mAh/cm2, about 4.8 mAh/cm2, about 5 mAh/cm2, about 5.5 mAh/cm2, about 6 mAh/cm2, about 6.5 mAh/cm2, about 6.6 mAh/cm2, about 7 mAh/cm2, about 7.5 mAh/cm2, about 8 mAh/cm2 or about 10 mAh/cm2, or any range of values therebetween. In further embodiments, an energy storage device electrode film, wherein the electrode film is dry and/or self-supporting film, may provide areal capacity (which may be expressed as capacity per unit area of electrode film or current collector) of at least about 8 mAh/cm2, for example, about 8 mAh/cm2, about 10 mAh/cm2, about 12 mAh/cm2, about 14 mAh/cm2, about 16 mAh/cm2, about 18 mAh/cm2, about 20 mAh/cm2, or any range of values therebetween. In some embodiments, the areal capacity is charging capacity. In further embodiments, the areal capacity is discharging capacity.
In some embodiments, a dry and/or self-supporting graphite battery anode electrode film may provide areal capacity of about 3.5 mAh/cm2, about 4 mAh/cm2, about 4.5 mAh/cm2, about 5 mAh/cm2, about 5.5 mAh/cm2, about 6 mAh/cm2, about 6.5 mAh/cm2, about 7 mAh/cm2, about 7.5 mAh/cm2, about 8 mAh/cm2, about 8.5 mAh/cm2, about 9 mAh/cm2, about 10 mAh/cm2, or any range of values therebetween. In some embodiments, the areal capacity is charging capacity. In further embodiments, the areal capacity is discharging capacity.
In some embodiments, an energy storage device electrode film, wherein the electrode film is dry and/or self-supporting film, may provide a specific capacity (which may be expressed as capacity per mass of electrode film or current collector) of about 150 mAh/g, about 160 mAh/g, about 170 mAh/g, about 175 mAh/g, about 176 mAh/g, about 177 mAh/g, about 179 mAh/g, about 180 mAh/g, about 185 mAh/g, about 190 mAh/g, about 196 mAh/g, about 200 mAh/g, about 250 mAh/g, about 300 mAh/g, about 350 mAh/g, about 354 mAh/g or about 400 mAh/g, or any range of values therebetween. In further embodiments, an energy storage device electrode film, wherein the electrode film is dry and/or self-supporting film, may provide specific capacity (which may be expressed as capacity per mass of electrode film or current collector) of at least about 175 mAh/g or at least about 250 mAh/g, or any range of values therebetween. In some embodiments, the specific capacity is charging capacity. In further embodiments, the specific capacity is discharging capacity. In some embodiments, the electrode may be an anode and/or a cathode. In some embodiment, the specific capacity may be a first charge and/or discharge capacity. In further embodiments, the specific capacity may be a charge and/or discharge capacity measured after the first charge and/or discharge.
In some embodiments, a self-supporting dry electrode film described herein may advantageously exhibit improved performance relative to a typical electrode film. The performance may be, for example, tensile strength, elasticity (extension), bendability, coulombic efficiency, capacity, or conductivity. In some embodiments, an energy storage device electrode film, wherein the electrode film is dry and/or self-supporting film, may provide a coulombic efficiency (which may be expressed as a percent of the discharge capacity divided by the charge capacity) of about, or at least about, 85%, 86%, 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94% or about 95%, or any range of values therebetween for example such as 90.1%, 90.5% and 91.9%, or any range of values therebetween.
In some embodiments, an energy storage device electrode film or electrode, wherein the electrode film is or the electrode comprises a dry and/or self-supporting film, may provide a charge capacity retention percentage (which may be expressed by the discharge capacity at a given rate divided by the discharge capacity measured at C/10) of about or at least about 10%, about or at least about 20%, about or at least about 30%, about or at least about 40%, about or at least about 50%, about or at least about 60%, about or at least about 70%, about or at least about 80%, about or at least about 90%, about or at least about 98%, about or at least about 99%, about or at least about 99.9% or about or at least about 100%, or any range of values therebetween. In some embodiments, the discharge rate of the charge capacity retention percentage is about or is at least about C/10, C/5, C/3, C/2, 1C, 1.5C or 2C, or any value therebetween.
In some embodiments, an energy storage device electrode film or electrode, wherein the electrode film is or the electrode comprises a dry and/or self-supporting film, may provide a charge capacity production percentage (which may be expressed by the charge capacity measured at a given constant current rate divided by the discharge capacity measured at C/10) of about or at least about 10%, about or at least about 20%, about or at least about, 30%, about or at least about, 40%, about or at least about 50% about or at least about 60%, about or at least about 70%, about or at least about 80%, about or at least about 90%, about or at least about 98%, about or at least about 99%, about or at least about 99.9% or about or at least about 100%, or any range of values therebetween. In some embodiments, the charge rate of the charge capacity production percentage is or is at least C/10, C/5, C/3, C/2, 1C, 1.5C or 2C, or any value therebetween.
In some embodiments, an energy storage device electrode film, wherein the electrode film is dry and/or self-supporting film, may provide a specific energy density or gravimetric energy density (which may be expressed as energy per mass of electrode film) of about 200 Wh/kg, about 210 Wh/kg, about 220 Wh/kg, about 230 Wh/kg, about 240 Wh/kg, about 250 Wh/kg, about 260 Wh/kg, about 270 Wh/kg, about 280 Wh/kg, about 290 Wh/kg, about 300 Wh/kg, about 400 Wh/kg, about 500 Wh/kg, about 600 Wh/kg, about 650 Wh/kg, about 700 Wh/kg, about 750 Wh/kg, about 800 Wh/kg, about 825 Wh/kg, about 850 Wh/kg or about 900 Wh/kg, or any range of values therebetween.
In some embodiments, an energy storage device electrode film, wherein the electrode film is dry and/or self-supporting film, may provide an energy density or volumetric energy density (which may be expressed as energy per unit volume of the final or in situ electrode film) of about 550 Wh/L, about 600 Wh/L, about 630 Wh/L, about 650 Wh/L, about 680 Wh/L, about 700 Wh/L, about 750 Wh/L, about 850 Wh/L, about 950 Wh/L, about 1100 Wh/L, about 1400 Wh/L, about 1425 Wh/L, about 1450 Wh/L, about 1475 Wh/L, about 1500 Wh/L, about 1525 Wh/L or about 1550 Wh/L, or any range of values therebetween.
In some embodiments, a self-supporting dry battery cathode may exhibit reduced ohmic resistance and/or improved voltage polarization characteristics compared to a wet battery cathode. In further embodiments, a lithium ion battery incorporating a self-supporting dry cathode may advantageously exhibit reduced ohmic resistance and/or improved voltage polarization characteristics compared to a lithium ion battery having a wet cathode and a wet anode. In still further embodiments, a lithium ion battery incorporating a self-supporting dry cathode may demonstrate improved energy density and/or specific energy density, as compared to a lithium ion battery including a wet cathode.
In some embodiments, a self-supporting dry battery electrode after aging may exhibit reduced ohmic resistance, improved voltage polarization characteristics and/or improved capacity compared to an aged wet battery electrode. In some embodiments, the dry battery electrode after aging exhibits a reduction of ohmic resistance that is about 5 fold, about 10 fold, about 15 fold or about 20 fold less than the reduction of ohmic resistance in a similarly aged wet battery electrode, or any range of values therebetween. In some embodiments, the dry battery electrode after aging exhibits reduction of voltage of about 1.5 times, about 2 times, about 3 times or about 5 times less than the reduction of voltage in a similarly aged wet battery electrode, or any range of values therebetween. In some embodiments, the dry battery electrode after aging exhibits reduction of capacity of about 1.5 times, about 2 times, about 3 times or about 5 times less than the reduction of capacity in a similarly aged wet battery electrode, or any range of values therebetween.
In specific examples below, high energy density, high specific energy density, high thickness and/or high electrode film density battery electrodes were fabricated.
As used herein, the terms “battery” and “capacitor” are to be given their ordinary and customary meanings to a person of ordinary skill in the art. The terms “battery” and “capacitor” are nonexclusive of each other. A capacitor or battery can refer to a single electrochemical cell that may be operated alone, or operated as a component of a multi-cell system.
As used herein, the voltage of an energy storage device is the operating voltage for a single battery or capacitor cell. Voltage may exceed the rated voltage or be below the rated voltage under load, or according to manufacturing tolerances.
As provided herein, a “self-supporting” electrode film is an electrode film that incorporates binder matrix structures sufficient to support the film or layer and maintain its shape such that the electrode film or layer can be free-standing. When incorporated in an energy storage device, a self-supporting electrode film or active layer is one that incorporates such binder matrix structures. Generally, and depending on the methods employed, such electrode films or active layers are strong enough to be employed in energy storage device fabrication processes without any outside supporting elements, such as a current collector or other film. For example, a “self-supporting” electrode film can have sufficient strength to be rolled, handled, and unrolled within an electrode fabrication process without other supporting elements. A dry electrode film, such as a cathode electrode film or an anode electrode film, may be self-supporting.
As provided herein, a “solvent-free” electrode film is an electrode film that contains no detectable processing solvents, processing solvent residues, or processing solvent impurities. A dry electrode film, such as a cathode electrode film or an anode electrode film, may be solvent-free.
A “wet” electrode, “wet process” electrode, or slurry electrode, is an electrode prepared by at least one step involving a slurry of active material(s), binder(s), and optionally additive(s). A wet electrode may include processing solvents, processing solvent residues, and/or processing solvent impurities.
Dry battery anodes were fabricated, which included 96% by weight graphite and 4% by weight binder, wherein the binder included 2% PTFE, 1% CMC and 1% PVDF by weight totaling the 4% of binder by weight. Cathodes were also fabricated in a dry process, the cathodes including 94% by weight NMC622, 3% by weight conductive additive, and 3% by weight polymer binder. In addition, wet process electrodes were fabricated having the following compositions: the wet process anode included 95.7% by weight graphite, 1% conductive additive, and 3.3% by weight polymer binders, and the wet process cathode included 91.5% by weight active component and 4.4% by weight conductive additive and 4.1% by weight polymer binder. Other electrode film compositions can be envisioned and prepared, and the disclosure herein is not limited to the specific compositions disclosed.
Four lithium ion batteries were assembled, following the scheme of Table 1. Each lithium ion battery of Table 1 was tested for specific capacity (see
As can be seen in
As seen in
As shown, dry battery electrodes can in some implementations elevate the electrochemical performance of an energy storage device. For example, a dry battery electrode was found to improve the performance of an energy storage device incorporating a wet process electrode, compared to an energy storage device incorporating only wet process electrodes. In particular, use of a self-supporting dry cathode was found to improve the performance of a lithium ion battery.
Two additional anodes were fabricated and tested. A first dry battery graphite anode was prepared using active material that was processed using a jet-milling step, and binder that was also processed using a jet-milling step (“Formula 1”). A second dry battery graphite anode was prepared using active material that was processed using a gentle powder process such as a tumble blender, and was not subject to a jet-milling step, and binder that was processed using a jet-milling step (“Formula 4”). Specific capacity and coulombic efficiency results appear in
Table 3 provides the electrode specifications for thick NMC622 cathode and thick graphite anode. The NMC622 cathode is composed of 94 wt % NMC622, 2 wt % porous carbon, 1 wt % conductive carbon and 3 wt % PTFE. The graphite anode is composed of 96 wt % graphite, 1.5 wt % CMC, 0.5 wt % PVDF and 2 wt % PTFE. The half-cell 1st cycle results are captured in
The dry NMC622 cathode is composed of about 95 wt % NMC622, 2 wt % porous carbon, 1 wt % conductive carbon and 2 wt % PTFE. The dry graphite anode is composed of about 96 wt % graphite, 1 wt % CMC, 1 wt % PVDF, 2 wt % PTFE. Further characteristics of the dry NMC622 cathode and dry graphite anode are shown below in Table 5.
The designed electrode areal capacity is about 6.6 mAh/cm2 and the cell format used to compare both coating technologies are identical. The charge rate used to establish cell capacity was measured at a C/10 rate, resulting in about 0.14 Ah for both dry and wet coated electrodes. As seen in
Table 6 provides the electrode specifications for thick NMC622 cathode and thick graphite anode produced by a dry process. The dry NMC622 cathode is composed of about 95 wt % NMC622, 2 wt % porous carbon, 1 wt % conductive carbon, and 2 wt % PTFE. The dry graphite anode is composed of about 96 wt % graphite, 1 wt % CMC, 1 wt % PVDF, and 2 wt % PTFE.
Table 7 provides the electrode specifications for thick NMC622 cathode and thick graphite anode produced by a wet process. The wet NMC622 cathode is composed of about 92 wt % NMC622, 4 wt % conductive carbon, and 4 wt % PVDF. The wet graphite anode is composed of about 96 wt % graphite, 1 wt % conductive carbon, and 3 wt % CMC/styrene-butadiene binder. The cell format used to compare coating technologies of Tables 5 and 6 are identical.
The cell voltage of the wet coated electrode is also impacted more severely than dry coated electrodes after 6 weeks of storage at 65 degrees Celsius and 100% SOC, as seen in
The high temperature storage conditions also significantly deteriorated the capacity of wet coated electrode cells compared to dry coated electrode cells after 6 weeks of aging, as seen in
The collection of comparative tests shown in
Electrode formulations and film calendering processes have been developed that improve electrode film density while maintaining physical properties and electrochemical performance of the electrode, and overcome the issues of wet casting high electrode material loadings previously described. Two electrode formulations comprising 94 wt % graphite active material and 6 wt % polymer binder that are calendered at temperatures ranging from 37° C. to about 150° C. Formula 1 is composed of 94 wt % graphite, 3 wt % CMC, and 3 wt % PTFE, and Formula 2 is composed of 94 wt % graphite, 2 wt % CMC, 1 wt % PVDF, and 3 wt % PTFE. It is demonstrated that significantly higher electrode film densities can be achieved by optimizing the formulation and calendering graphite electrodes at lower temperatures. The electrode film densities for Formulations 1 and 2 calendered at a number of temperatures are shown in Table 8 below.
Furthermore,
In some instances, a solid state energy storage device comprising an electrode film described herein is disclosed. In some embodiments, the solid state energy storage device is a solid state battery. Solid state batteries provide improved safety by employing non-flammable components. Additionally, solid state batteries are able to safely utilize elemental lithium metal because dendrite formation is not as severe relative to typical liquid-based lithium ion batteries. Lithium metal offers a significantly higher theoretical specific capacity compared to graphite, and therefore it can improve energy density over typical lithium ion batteries. Furthermore, a dry electrode processing method is expected to be less expensive and safer than conventional methods. Typically, a solid state lithium battery comprises an ionic and/or electronic conducting cathode, a solid electrolyte and a lithium metal anode. In some embodiments, at least one of the solid electrodes comprises a solid electrolyte salt. In some embodiments, the solid electrolyte is an ion conducting inorganic solid electrolyte. In some embodiments, the solid electrolyte is a polymer-based film. In some embodiments, a dry processed composite solid polymer electrolyte (SPE).
In some embodiments, the solid electrolyte salt is a lithium salt. In some embodiments, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide, lithium bis(pentafluoroethanesulfonyl)imide, lithium bis(oxalato)borate, and lithium perchlorate. In some embodiments, the electrode salt has a garnet structure, for example, Li6.5La3Zr1.5Ta0.5O12, Li6La3SnMO12 (M=Sb, Nb, Ta, Zr), Li5La3Ta2O12 and Li3N. In some embodiments, the electrode salt is a sulfur based electrode salt, for example Li2S—P2S5 and Li2S—P2S5—Li3PO4. In some embodiments, the electrode salt is Li0.5La0.5TiO3 (LLTO) and/or Li7La3Zr2O12 (LLZO). In some embodiments, the electrode salt is a LISCON (Lithium Super Ionic Conductor), for example the LISCON may have a molecular formula of Li(2+2x)Zn(1−x)GeO4.
In some embodiments, the composite solid polymer electrolyte (SPE) comprises at least one ion conducting polymer. In some embodiments, the SPE comprises at least one lithium ion salt. In some embodiments, the SPE comprises at least one supporting polymer binder. In some embodiments, the SPE comprises at least one filler. In some embodiments, the SPE comprises at least one ion conducting polymer and at least one lithium ion salt. In some embodiments, the SPE comprises at least one ion conducting polymer, at least one one lithium ion salt and at least one supporting polymer. In some embodiments, the SPE comprises at least one ion conducting polymer, at least one lithium ion salt, at least one supporting polymer and at least one filler.
In some embodiments, the ion conducting polymer is selected from at least one of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), poly(methylene oxide), polyoxymethylene, poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP), poly(methyl methacrylate), poly(vinyl acetate), poly(vinylchloride), poly(vinyl acetate), poly(oxyethylene)9methacrylate, poly(ethylene oxide) methyl ether methacrylate, and poly(propylenimine).
In some embodiments, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(pentafluoroethanesulfonyl)imide, lithium perchlorate (LiClO4), lithium bis(trifluoromethane sulfonimide) (LiTFSI) (Li(C2F5SO2)2N), lithium bis(oxalato)borate (LiB(C2O4)2), lithium trifluoromethanesulfonate (LiCF3SO3), Li6.4La3Zr1.4Ta0.6O12, Li7La3Zr2O12, Li10SnP2S12, Li3xLa2/3−xTiO3, Li0.8La0.6Zr2(PO4)3, Li1+xTi2−xAlx(PO4)3, Li1+x+yTi2−xAlxSiy(PO4)3−y, and LiTixZr2−x(PO4)3. In some embodiments, the lithium salt may be a lithium salt previously described herein.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the systems and methods described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.
Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a sub combination.
Moreover, while operations may be depicted in the drawings or described in the specification in a particular order, such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results. Other operations that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated and/or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added. Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products. For example, any of the components for an energy storage system described herein can be provided separately, or integrated together (e.g., packaged together, or attached together) to form an energy storage system.
For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.
Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or steps are included or are to be performed in any particular embodiment.
Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.
Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount, depending on the desired function or desired result.
The headings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the devices and methods disclosed herein.
The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive.
Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57. This application claims the benefit of priority under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 62/590,110, filed Nov. 22, 2017.
| Number | Date | Country | |
|---|---|---|---|
| 62590110 | Nov 2017 | US |
