Patent Application
20200220163
This application claims priority to and benefits of Chinese Patent Application Serial No. 201910016479.0, filed with China National Intellectual Property Administration on Jan. 8, 2019, the entire content of which is incorporated herein by reference.
The present application is related generally to the field of energy storage devices, and in particular, to composite electrode for lithium ion batteries.
Mobile electronic devices and electric vehicles have emerged and become indispensable in people's daily life. As common energy devices that power the mobile electronic products, lithium ion batteries have multiple advantages such as high energy density (e.g., an amount of energy per volume), high power density (e.g., an amount of power per volume), high working voltage, and low self-discharge rate. Thus lithium ion batteries have been widely used in various electronic products, including mobile devices and electric vehicles.
Fast development and high performance demand in various electronic devices and electric vehicles require lithium ion batteries to retain high energy density after many charge-discharge cycles. However, because lithium metal is extremely active, lithium metal anodes can easily undergo a series of side reactions with the organic small molecules (e.g., carbonate esters, phosphate esters, and/or certain types of organic compounds including an ether group) in the electrolyte, resulting in undesirable consumptions of both lithium metal anode and electrolyte in a battery. As a result, the coulombic efficiency of the battery significantly reduces after many cycles.
In addition, conventional lithium ion batteries also pose safety concerns due to dendrite growth on the anode surface that may cause short circuit to the batteries. For example, when charging a battery including a lithium metal anode, lithium metal is deposited on the surface of the anode current collector. Because the current density may not be homogeneously distributed in the anode current collector, and the Li+ ions concentration may not be uniform in the electrolyte, lithium metal may be deposited faster on certain sites of the anode current collector than others, forming a sharp dendritic structure. Lithium dendrites can lead to significantly reduced deposition density when charging the battery, resulting in decreased energy density. Moreover, dendrites may pierce the separator in the battery to cause short circuit, resulting in serious safety problems.
Further, inhomogeneous lithium metal deposition in conventional lithium ion batteries suffer from drastic changes in anode thickness and battery volume. After many charge-discharge cycles, the battery volume change may cause separation of the anodes from other components in the battery, resulting in increased impedance, and even deformation of the battery.
Accordingly, it would be desirable to have lithium ion batteries with improved structure and performance to solve at least the above mentioned problems and accommodate the need from the mobile electronic devices.
According to an aspect of the present application, an electrode for a battery comprises a current collector having a first surface. The electrode further comprises a composite layer disposed in a first region on the first surface of the current collector. The composite layer has a first material with a scaffold structure and a second material mixed with the scaffold structure. The second material includes electrochemically active material for the battery. The electrode further comprises an insulation layer disposed in a second region surrounding the first region on the first surface of the current collector. The electrode further comprises a protection layer that covers the composite layer and the insulation layer on the first surface of the current collector.
According to another aspect of the present application, a battery comprises a double-sided anode including an anode current collector having a first surface and a second surface opposite to the first surface. Each of the first and second surfaces further comprises a composite layer disposed in a first region on a respective surface of the anode current collector. The composite layer has a first material with a scaffold structure and a second material mixed with the scaffold structure. The second material includes electrochemically active material for the battery. Each surface of the anode current collector further comprises an insulation layer disposed in a second region surrounding the first region on the respective surface of the anode current collector. Each surface of the anode current collector also comprises a protection layer that covers the composite layer and the insulation layer on the respective surface of the anode current collector. The battery further comprises a first single-sided cathode including a first cathode active material coated on one side of a first cathode current collector. The battery also comprises a first separator disposed between the first cathode active material on the side of the first cathode current collector and the protection layer on the first surface of the anode current collector. The battery further comprises a second single-sided cathode including a second cathode active material coated on one side of a second cathode current collector. Moreover, the battery comprises a second separator disposed between the second cathode active material on the side of the second cathode current collector and the protection layer on the second surface of the anode current collector.
According to yet another aspect of the present application, a battery comprises an anode including an anode current collector having a first surface. The anode also comprises a composite layer disposed in a first region on the first surface of the anode current collector. The composite layer has a first material with a scaffold structure and a second material mixed with the scaffold structure. The second material includes electrochemically active material for the battery. The anode further comprise an insulation layer disposed in a second region surrounding the first region on the first surface of the anode current collector. The anode also comprises a protection layer that covers the composite layer and the insulation layer on the first surface of the anode current collector. The battery also comprises a cathode including a cathode active material coated on a first surface of a cathode current collector. The battery further comprises a separator disposed between the cathode active material on the first surface of the cathode current collector and the protection layer on the first surface of the anode current collector.
The accompanying drawings, which are included to provide a further understanding of the embodiments and are incorporated herein and constitute a part of the specification, illustrate the described embodiments and together with the description serve to explain the underlying principles. Like reference numerals refer to corresponding parts.
Reference will now be made in detail to specific embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous non-limiting specific details are set forth in order to assist in understanding the subject matter presented herein. But it will be apparent to one of ordinary skill in the art that various alternatives may be used without departing from the scope of claims and the subject matter may be practiced without these specific details. For example, it will be apparent to one of ordinary skill in the art that the subject matter presented herein can be implemented on many types of energy storage devices, such as batteries. The terms “front”, “behind”, “left”, “right”, “upper” and “lower” described in the present application are given with reference to the state where a current collector is disposed in the accompanying drawings.
In some embodiments, the composite electrode 100 is an anode of the lithium ion battery, and the current collector 110 is an anode current collector. In some embodiments, the anode current collector comprises a copper (Cu) sheet.
In some embodiments, the composite layer 120 includes a scaffold structure mixed with an electrochemically active material that participates in the electrochemical reactions when charging and discharging the lithium ion battery. In some embodiments, the scaffold structure is made of a first material that is capable of conducting ions, such as Li+ ions, to facilitate ion diffusion within the composite electrode 100 when charging and discharging the lithium ion battery. In some embodiments, an ionic conductivity of the first material that forms the scaffold structure is in a range from 10−2 S/cm to 10−8 S/cm. In some embodiments, the first material is an electronic insulation material (e.g., does not conduct electrons). In some embodiments, the first material is porous and has a porosity in a range from 30% to 85%. If the porosity of the first material is too high, the scaffold structure may not be strong and stable enough to support the electrochemically active material in the composite layer 120. In some embodiments, the first material is electrochemically active and may participate in the electrochemical reactions (e.g., may contribute to the capacity of the battery) when charging and discharging the lithium ion battery. In some embodiments, the first material is electrochemically inactive and does not participate in the electrochemical reaction of the lithium ion battery.
In some embodiments, the first material used to form the scaffold structure includes ionic conductive polymer materials, such as polyethylene oxide (PEO). In some embodiments, the first material comprises one or more monomers of one or more polymers including PEO and/or others polymers disclosed in the present disclosure. In some embodiments, the first material includes carbon-based material, such as porous carbon, carbon nanotubes, carbon fiber, or hollow carbon spheres. In some embodiments, the first material includes inorganic solid electrolyte material, such as lithium titanium phosphate (LixTiy(PO4)3 (0<x<2, 0<y<3)), lithium aluminum titanium phosphate (LixAlyTiz(PO4)3 (0<x<2, 0<y<1, 0<z<3)), Li1+x+y(Al,Ga)x(Ti,Ge)2-xSiyP3-yO12 (0≤x≤1, 0≤y≤1), lithium strontium titanate (LixLayTiO3 (0<x<2, 0<y<3), Li2O—Al2O3—SiO2—P2O5—TiO2—GeO2 ceramic materials, or garnet ceramic materials (Li3+xLa3M2O12 (0≤x≤5, M is Te, Nb, or Zr)).
In some embodiments, the electrochemically active material of the composite layer 120 includes a second material different from the first material and mixed with the scaffold structure. In some embodiments, the second material provides Li+ ions reduction/oxidation, Li+ ions intercalation/de-intercalation, and/or Li+ ions insertion/extraction when charging/discharging the lithium ion battery.
In some embodiments, the composite electrode 100 is an anode, and the second material for the anode (e.g., anode active materials) includes one material or a mixture of two or more materials selected from lithium metal (Li), carbon-based anode (e.g., graphite, graphene, carbon nanotubes, carbon nanowires, etc.), tin(Sn)-based anode (e.g., SnO2, Sn-based composites, Sn-based compounds, Sn-based alloys), silicon(Si)-based anode (e.g., SiO2, Si-based composites, Si-based compounds), titanium oxide (TiO2), Ti-based alloys, and iron oxide (Fe2O3, Fe3O4, etc.).
In some embodiments, the composite layer 120 is formed by applying a pressure to the second material having certain fluidity (e.g., softened or molten metal) against the first material to homogeneously mix the second material with the scaffold structure. In some other embodiments, the second material can also be deposited onto surfaces of the scaffold structure. Other possible methods can also be used to homogeneously mix the second material with the scaffold structure. In some embodiments, the composite layer 120 has a thickness (“t1” along Y direction in
The composite layer including a scaffold structure mixed with electrochemically active materials can provide several benefits to the performance of the lithium ion battery. First, the scaffold structure provides extra space in the electrode to accommodate more Li+ ions to diffuse into the internal space of the electrode, so as to avoid drastic volume change after many charging and discharging cycles and avoid the one or more layers detached from the current collector 110 or separator (e.g., separator 310 or 340,
In some embodiments, the insulation layer 130 is disposed along the edges (e.g., the insulation layer 130 covers the regions on the surface and near the edges as shown in
In some embodiments, the insulation layer 130 has a thickness (“t2” along Y direction in
In some embodiments, the insulation layer 130 comprises electronic insulating and ionic insulating material, i.e., the insulation layer 130 does not conduct electrons or ions. In some embodiments, the materials used in the insulation layer 130 has a resistivity in a range from 107 Ω·m to 1022 Ω·m. In some preferred embodiments, the resistivity of the materials used in the insulation layer is in a range from 1010 Ω·m to 1022 Ω·m. In some embodiments, the insulation layer 130 is configured to confine the Li+ ions diffusion and Li+ ions reduction/oxidation within a range defined by the insulation layer 130. That is, the Li+ ions diffusion and Li+ ions reduction/oxidation do not take place outside the region enclosed by the insulation layer 130. In some embodiments, the insulation layer 130 covers the edges of the current collector 110 and further extends from the first surface to the second opposing surface of the current collector 110 to cover the cross sectional edges of the current collector 110. The insulation layer 130 as disclosed herein can effectively prevent the direct contact between current collector 110 and protection layers 140, so that electrons conducted within the current collector 110 cannot directly contact or react with (e.g., reduce) Li+ ions diffused within the protection layers 140. Instead, Li+ ions can only be reduced to Li metal in the composite layer 120. Therefore, the insulation layer 130 further defines/confines the region where Li+ ions can meet electrons to have redox reactions. The insulation layer 130 prevents Li metal from depositing on the insulation layer 130 or the protection layers when charging and discharging the battery.
In some embodiments, the insulation layer 130 comprises polymer or inorganic insulation materials. In some embodiments, the insulation layer 130 comprises one or more polymer insulation materials such as polyimide, polyvinyl fluoride, polyether ether ketone (PEEK), polyester, polyethylene, polypropylene, polyvinylidene chloride, polytetrafluoroethylene (PTFE), and/or polyethylene terephthalate (PET). In some embodiments, the insulation layer 130 comprises one or more inorganic ceramic materials such as alumina (Al2O3), aluminum hydroxide (Al(OH)3), and/or boron nitride (BN).
In some embodiments, the one or more protection layers 140 are ionic conductive while electronic insulating. In some embodiments, the ionic conductivity of the materials of the protection layers 140 is in a range from 10−2 S/cm to 10−8 S/cm. In some embodiments, the protection layers 140 are electrochemically inactive.
In some embodiments, the one or more protection layers 140 completely covers the composite layer 120, the insulation layer 130, and any gap between the composite layer 120 and the insulation layer 130. In some embodiments, an overlapped region between the one or more protection layers 140 and the insulation layer 130 has a width (e.g., a dimension along X direction in
In some embodiments as illustrated in
In some embodiments, the protection layers 140 have a porosity lower than 5%. In some embodiments, any pore in the protection layers 140 has a diameter that is smaller than 1 in. The protection layers have low porosity and small pore size to effectively block or significantly reduce the passage of electrolyte into the anode, so as to reduce the side reactions between lithium metal anode and molecules in the electrolyte, and increase the coulombic efficiency of the battery.
In some embodiments, the one or more protection layers 140 comprise one or more polymer materials (e.g., ionic conductive polymer materials), such as polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), poly(p-phenylene oxide) (PPO), polyphenylene ether (PPE), polypropylene carbonate (PPC), and/or polyethylene oxide (PEO). In some embodiments, the one or more protection layers 140 comprise one or more monomers of the above listed polymers and/or other polymers as disclosed in the present disclosure. In some embodiments, the one or more protection layers 140 comprise inorganic ceramic materials, such as HfO2, SrTiO3, SnO2, CeO2, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, and/or SiO2. In some preferred embodiments, the one or more protection layers 140 preferably comprise materials that are good Li+ ions conductors, such as lithium phosphate (Li3PO4), lithium titanium phosphate (LixTiy(PO4)3(0<x<2, 0<y<3)), lithium aluminum titanium phosphate (LixAlyTiz(PO4)3(0<x<2, 0<y<1, 0<z<3)), Li1+x+y(Al,Ga)x(Ti,Ge)2-xSiyP3-yO12 (0≤x≤1, and 0≤y≤1), lithium strontium titanate (LixLayTiO3 (0<x<2, 0<y<3), lithium bismuth thiophosphate (LiGeyPzSz, 0≤x<4, 0<y<1, 0<z<1 or 0<w<5), lithium nitride (LixNy, 0<x<4, 0<y<2), SiS2 glass (LixSiySz, 0<x<3, 0<y<2, 0<z<4), P2S5 glass (LixPySz, 0≤x<3, 0<y<3, 0<z<7), Li2O, LiF, LiOH, Li2CO3, LiAlO2, Li2O—Al2O3—SiO2—P2O5—TiO2—GeO2 ceramics, and/or garnet ceramics (Li3+xLa3M2O12, 0≤x≤5, and M is one or more selected from Te, Nb, and Zr).
In some embodiments, the one or more protection layers 140 are attached to the upper surfaces of the insulation layer 130 and the composite layer 120 by hot pressing. In some embodiments, a temperature used for hot pressing is selected to be the lower one between the respective melting temperatures of the separator and the insulation layer 130 in the battery, and a pressure is between 0.1 Mpa and 2 Mpa. In some other embodiments, the insulation layer 130, the composite layer 120, and the one or more protection layers 140 are bound by one or more binder materials, such as polyamide, polyurethane, ethylene-vinyl acetate (EVA), ethylene vinyl alcohol (EVOH), acrylate, and/or polyvinylidene fluoride or polyvinylidene difluoride (PVDF). In some other embodiments, the one or more protection layers 140 are directly deposited on the upper surfaces of the insulation layer 130 and the composite layer 120 without using any binder materials (e.g., using any suitable chemical deposition method or physical deposition method). After forming the protection layers 140 on the composite layer 120, an upper portion of the scaffold structure in the composite layer 120 penetrates into the protection layers 140 for a depth (along Y direction in
In some embodiments, the respective electrochemically active regions of the cathode layer 320 and the anode composite layer 120 have the same area and directly face each other, and the respective electrochemically active regions of the cathode layer 350 and the anode composite layer 160 have the same area and directly face each other. In some other embodiments, the cathode layer 320 has a larger electrochemically active area than that of the anode composite layer 120, and the cathode layer 350 has a larger electrochemically active area than that of the anode composite layer 160. In some other embodiments, the cathode layer 320 has a smaller electrochemically active area than that of the anode composite layer 120, and the cathode layer 350 has a smaller electrochemically active area than that of the anode composite layer 160.
In some embodiments, a respective separator of the first separator 310 and the second separator 340 comprises one or more materials selected from polyethylene, polypropylene, polyethylene terephthalate, polyimide, and aramid. For example, polyethylene for the separator can be high-density polyethylene, low-density polyethylene, or polyethylene with ultra-high molecular weight. Polyethylene separator and polypropylene separator can effectively prevent short-circuit between the cathode current collector and the anode current collector and thus improve stability and cyclability of the battery. In some embodiments, one or both surfaces of the separator are porous, and the porous layer may include inorganic particles and binders. In some embodiments, the inorganic particles include one or more inorganic compounds selected from aluminum oxide (Al2O3), silicon oxide (SiO2), magnesium oxide (MgO), titanium oxide (TiO2), hafnium dioxide (HfO2), tin oxide (SnO2), cerium oxide (CeO2), nickel oxide (NiO), zinc oxide (ZnO), calcium oxide (CaO), zirconium oxide (ZrO2), yttrium oxide (Y2O3), silicon carbide (SiC), boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate. In some embodiments, the binders include one or more types of materials selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, carboxymethylcellulose sodium, polyvinyl pyrrolidone, polyethylene, polymethylmethacrylate, polytetrafluoroethylene, and polyhexafluoropropylene. The porous surface can improve thermal resistance and oxidation resistance of the separator. The porous surface can also have an improved electrolyte infiltration effect to provide a better contact between the separator and the cathode and anode.
In some embodiments, a respective cathode of the first cathode layer 320 and the second cathode layer 350 comprises a material or a mixture of two or more materials selected from LiCoO2, LiNiO2, LiMn2O4, LiFePO4, LiMnPO4, LiCoPO4, Li2MxMn4-xO8 (M=Fe, Co), MnO2, V2O5, TiS2, and MoS2. In some embodiments, the compatibilities of working voltages and chemistry between the cathode and the anode may also be considered when selecting the cathode active material for the lithium ion battery 300. In some embodiments, the cathode active materials have various particle shapes, such as nanoparticles, nanotubes, nanopowders, nanoballs, nanoflakes, nanowires, etc. In some embodiments, the active material is mixed with additives and binders to form a paste which is then coated on the cathode current collector to form a cathode. In some other embodiments, the active material can be deposited onto the cathode current collector using any suitable method, such as chemical vapour deposition (CVD), physical vapour deposition (PVD), pulsed laser deposition (PLD), magnetron sputtering deposition, electrochemical depo, epitaxial growth, spin coating method, etc.
In some embodiments, a respective current collector of the first cathode current collector 330 and the second cathode current collector 360 comprises an aluminium (Al) sheet.
In some embodiments, the battery 300 includes an electrolyte (not shown) disposed between the cathode and the anode. In some embodiments, the battery 140 can use a liquid electrolyte, a gel electrolyte, or a solid electrolyte. The liquid electrolyte can be one or more lithium-based salts selected from LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiSiF6, LiBO and LIODFB dissolved in a nonaqueous solvent.
In some embodiments, the nonaqueous solvent includes a carbonate ester compound, a carboxylic acid compound, an ether compound, other suitable organic solvent, or a combination thereof. In some embodiments, the carbonate ester compound may be a chain carbonate compound, a cyclic carbonate compound, a fluorocarbonate compound, or a combination thereof. Examples of chain carbonate compounds include diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylene carbonate (EPC), carbonic acid ethyl acetate (MEC), and combinations thereof. Examples of cyclic carbonate compounds include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinyl ethylene carbonate (VEC), and combinations thereof. Examples of fluorocarbonate compounds include fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, and 1,1,2-tricarboxylic acid, fluoroethylene, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethyl carbonate, 1-fluoro-1-methyl-ethylene carbonate, carbonic acid 1,2-Difluoro-1-methylethylene, 1,1,2-trifluoro-2-methylethyl carbonate, trifluoromethyl ethylene carbonate, and combinations thereof. Examples of carboxylic acid ester compounds include methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, terpene lactone, valerolactone, DL-mevalonic acid lactone, caprolactone, methyl formate, and combinations thereof. Examples of ether compounds include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, and Ethoxymethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and combinations thereof. Examples of other organic solvents include dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, Formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, phosphate esters, and combinations thereof.
In some embodiments, the lithium ion battery 300 is packaged using packaging material (not shown) that includes three layers. In some embodiments, the inner layer (closest to the electrodes) is made of a polymer material such as polypropylene. The outer layer may be made of a polymer material such as nylon. In some embodiments, the middle layer disposed between the inner layer and the outer layer is a metal layer, such as an aluminum (Al) or a stainless steel sheet.
The following embodiments are various examples of preparing lithium ion batteries using the electrode structures discussed with reference to
An anode current collector (e.g., the current collector 110,
Next, a lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is placed on the thin film of nanofibers. A pressure of 0.1 MPa is applied to press the lithium metal foil towards the thin film of nanofibers and held for 5 seconds, to obtain a mixed composite layer (e.g., the composite layer 120,
Next, an insulation layer (e.g., the insulation layer 130,
Next, a lithium phosphorous oxynitride (LiPON) layer (e.g., as the protection layer 140,
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5, and adding solvent N-methylpyrrolidone (NMP) to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes (e.g.,
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to obtain an electrolytic solution having the lithium salt concentration of 1.15 M (mol/L).
To form a lithium ion battery as shown in
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Embodiment 1 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
An anode current collector (e.g., the current collector 110,
Next, a lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is placed on the thin film of nanofibers. A pressure of 0.1 MPa is applied to press the lithium metal foil towards the thin film of nanofibers and held for 5 seconds, to obtain a mixed composite layer (e.g., the composite layer 120,
Next, an insulation layer (e.g., the insulation layer 130,
Next, a lithium phosphorous oxynitride (LiPON) layer (e.g., as the protection layer 140,
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5. Solvent N-methylpyrrolidone (NMP) is added to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes (e.g.,
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to obtain an electrolytic solution having the lithium salt concentration of 1.15 M (mol/L).
To form a lithium ion battery as shown in
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Embodiment 2 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
An anode current collector (e.g., the current collector 110,
Next, a lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is placed on the thin film of nanofibers. A pressure of 0.1 MPa is applied to press the lithium metal foil towards the thin film of nanofibers and held for 5 seconds, to obtain a mixed composite layer (e.g., the composite layer 120,
Next, an insulation layer (e.g., the insulation layer 130,
Next, a lithium phosphorous oxynitride (LiPON) layer (e.g., as the protection layer 140,
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5. Solvent N-methylpyrrolidone (NMP) is added to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes (e.g.,
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to obtain an electrolytic solution having the lithium salt concentration of 1.15 M (mol/L).
To form a lithium ion battery as shown in
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Embodiment 3 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
An anode current collector (e.g., the current collector 110,
Next, a lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is placed on the carbon film of hollow carbon spheres. The carbon film and the lithium metal foil are placed in argon (Ar) atmosphere and heated to 300° C. Then a pressure of 0.01 MPa is applied to press the lithium metal foil towards the carbon film and held for 1 minute, to obtain a mixed composite layer (e.g., the composite layer 120,
Next, an insulation layer (e.g., the insulation layer 130,
Next, a lithium phosphorous oxynitride (LiPON) layer (e.g., as the protection layer 140,
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5. Solvent N-methylpyrrolidone (NMP) is added to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes (e.g.,
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to obtain an electrolytic solution having the lithium salt concentration of 1.15 M (mol/L).
To form a lithium ion battery as shown in
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Embodiment 4 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
An anode current collector (e.g., the current collector 110,
Next, a lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is placed on the Li7La3Zr2O12 scaffold layer. The scaffold layer and the lithium metal foil are placed in argon (Ar) atmosphere and heated to 300° C. Then a pressure of 0.01 MPa is applied to press the lithium metal foil towards the carbon film and held for 1 minute, to obtain a mixed composite layer (e.g., the composite layer 120,
Next, an insulation layer (e.g., the insulation layer 130,
Next, a lithium phosphorous oxynitride (LiPON) layer (e.g., as the protection layer 140,
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5. Solvent N-methylpyrrolidone (NMP) is added to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes (e.g.,
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to obtain an electrolytic solution having the lithium salt concentration of 1.15 M (mol/L).
To form a lithium ion battery as shown in
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Embodiment 5 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
An anode current collector (e.g., the current collector 110,
Next, a lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is placed on the Li7La3Zr2O12 scaffold layer. The scaffold layer and the lithium metal foil are placed in argon (Ar) atmosphere and heated to 300° C. Then a pressure of 0.01 MPa is applied to press the lithium metal foil towards the carbon film and held for 1 minute, to obtain a mixed composite layer (e.g., the composite layer 120,
Next, an insulation layer (e.g., the insulation layer 130,
Next, a protection layer (e.g., the protection layer 140,
Next, similar steps can be used to form the composite layer, the insulation layer, and the dense PEO protection layer on the opposite surface of the anode current collector to obtain a double-sided anode sheet as shown in
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5. Solvent N-methylpyrrolidone (NMP) is added to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes (e.g.,
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to obtain an electrolytic solution having the lithium salt concentration of 1.15 M (mol/L).
To form a lithium ion battery as shown in
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Embodiment 6 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
An anode current collector (e.g., the current collector 110,
Next, a lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is placed on the Li7La3Zr2O12 scaffold layer. The scaffold layer and the lithium metal foil are placed in argon (Ar) atmosphere and heated to 300° C. Then a pressure of 0.01 MPa is applied to press the lithium metal foil towards the carbon film and held for 1 minute, to obtain a mixed composite layer (e.g., the composite layer 120,
Next, an insulation layer (e.g., the insulation layer 130,
Next, a protection layer (e.g., the protection layer 140,
Next, similar steps can be used to form the composite layer, the insulation layer, and the dense PEO protection layer on the opposite surface of the anode current collector to obtain a double-sided anode sheet as shown in
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5. Solvent N-methylpyrrolidone (NMP) is added to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes (e.g.,
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to obtain an electrolytic solution having the lithium salt concentration of 1.15 M (mol/L).
To form a lithium ion battery as shown in
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Embodiment 7 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
An anode current collector (e.g., the current collector 110,
Next, a lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is placed on the Li7La3Zr2O12 scaffold layer. The scaffold layer and the lithium metal foil are placed in argon (Ar) atmosphere and heated to 300° C. Then a pressure of 0.01 MPa is applied to press the lithium metal foil towards the carbon film and held for 1 minute, to obtain a mixed composite layer (e.g., the composite layer 120,
Next, an insulation layer (e.g., the insulation layer 130,
Next, a protection layer (e.g., the protection layer 140,
Next, similar steps can be used to form the composite layer, the insulation layer, and the dense PEO protection layer on the opposite surface of the anode current collector to obtain a double-sided anode sheet as shown in
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5. Solvent N-methylpyrrolidone (NMP) is added to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes (e.g.,
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to obtain an electrolytic solution having the lithium salt concentration of 1.15 M (mol/L).
To form a lithium ion battery as shown in
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Embodiment 8 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
An anode current collector (e.g., the current collector 110,
Next, a lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is placed on the Li7La3Zr2O12 scaffold layer. The scaffold layer and the lithium metal foil are placed in argon (Ar) atmosphere and heated to 300° C. Then a pressure of 0.01 MPa is applied to press the lithium metal foil towards the carbon film and held for 1 minute, to obtain a mixed composite layer (e.g., the composite layer 120,
Next, an insulation layer (e.g., the insulation layer 130,
Next, a protection layer (e.g., the protection layer 140,
Next, similar steps can be used to form the composite layer, the insulation layer, and the dense PEO protection layer on the opposite surface of the anode current collector to obtain a double-sided anode sheet as shown in
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5. Solvent N-methylpyrrolidone (NMP) is added to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes (e.g.,
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to obtain an electrolytic solution having the lithium salt concentration of 1.15 M (mol/L).
To form a lithium ion battery as shown in
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Embodiment 9 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
An anode current collector having a dimension of 40 mm×60 mm is made by punching or cutting from a copper metal sheet. A lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is disposed on a first surface of the anode current collector. Next, another lithium metal foil with the same parameters (e.g., 38 mm×58 mm and 20 μm thick) is disposed on a second surface opposite to the first surface of the anode current collector to obtain a double-sided anode.
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5. Solvent N-methylpyrrolidone (NMP) is added to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes for lithium ion batteries.
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to obtain an electrolytic solution having the lithium salt concentration of 1.15 M (mol/L).
To form a lithium ion battery, the double-sided anode (or negative electrode, as prepared in Controlled Experiment 1 step (1)) is placed in the middle, and two single-sided cathodes (or positive electrode, as prepared in Controlled Experiment 1 step (2)) are disposed on two opposite sides of the anode respectively. A polyethylene (PE) film with a thickness of 15 μm is used as a respective separator disposed between each pair of the cathode and anode.
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Controlled Experiment 1 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
An anode current collector having a dimension of 40 mm×60 mm is made by punching or cutting from a copper metal sheet. Then, a scaffold layer comprising a garnet ceramic material Li7La3Zr2O12 is coated on a first region of the anode current collector. In some embodiments, the first region includes a center region of the anode current collector. In some embodiments, the scaffold layer has a thickness of about 80 μm, an area of about 38 mm×58 mm, and a porosity of about 60%. In some embodiments, the scaffold layer is coated from a slurry comprising garnet ceramic material Li7La3Zr2O12 and styrene butadiene rubber (SBR) at a mass ratio of 99:1. In some embodiments, the scaffold layer has the scaffold structure in the composite layer 120 of the anode as discussed with reference to
Next, a lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is placed on the Li7La3Zr2O12 scaffold layer. The scaffold layer and the lithium metal foil are placed in argon (Ar) atmosphere and heated to 300° C. Then a pressure of 0.01 MPa is applied to press the lithium metal foil towards the carbon film and held for 1 minute, to obtain a mixed composite layer (e.g., the composite layer 120,
Next, similar steps can be used to form a similar composite layer, which includes a Li7La3Zr2O12 scaffold layer supporting Li metal, on the opposite surface of the anode current collector to obtain a double-sided anode sheet.
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5. Solvent N-methylpyrrolidone (NMP) is added to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes for lithium ion batteries.
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to obtain an electrolytic solution having the lithium salt concentration of 1.15 M (mol/L).
To form a lithium ion battery, the double-sided anode (or negative electrode, as prepared in Controlled Experiment 2 step (1)) is placed in the middle, and two single-sided cathodes (or positive electrode, as prepared in Controlled Experiment 2 step (2)) are disposed on two opposite sides of the anode respectively. A polyethylene (PE) film with a thickness of 15 μm is used as a respective separator disposed between each pair of the cathode and anode.
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Controlled Experiment 2 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
An anode current collector having a dimension of 40 mm×60 mm is made by punching or cutting from a copper metal sheet. Then, a scaffold layer comprising a garnet ceramic material Li7La3Zr2O12 is coated on a first region of the anode current collector. In some embodiments, the first region includes a center region of the anode current collector. In some embodiments, the scaffold layer has a thickness of about 80 m, an area of about 38 mm×58 mm, and a porosity of about 60%. In some embodiments, the scaffold layer is coated from a slurry comprising garnet ceramic material Li7La3Zr2O12 and styrene butadiene rubber (SBR) at a mass ratio of 99:1. In some embodiments, the scaffold layer has the scaffold structure in the composite layer 120 of the anode as discussed with reference to
Next, a lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is placed on the Li7La3Zr2O12 scaffold layer. The scaffold layer and the lithium metal foil are placed in argon (Ar) atmosphere and heated to 300° C. Then a pressure of 0.01 MPa is applied to press the lithium metal foil towards the carbon film and held for 1 minute, to obtain a mixed composite layer (e.g., the composite layer 120,
Next, a protection layer (e.g., the protection layer 140,
Next, similar steps can be used to form the composite layer and the dense PEO protection layer on the opposite surface of the anode current collector to obtain a double-sided anode sheet.
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5. Solvent N-methylpyrrolidone (NMP) is added to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes for lithium ion batteries.
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to Obtain an Electrolytic Solution Having the Lithium Salt Concentration of 1.15 M (Mol/L).
To form a lithium ion battery, the double-sided anode (or negative electrode, as prepared in Controlled Experiment 3 step (1)) is placed in the middle, and two single-sided cathodes (or positive electrode, as prepared in Controlled Experiment 3 step (2)) are disposed on two opposite sides of the anode respectively. A polyethylene (PE) film with a thickness of 15 μm is used as a respective separator disposed between each pair of the cathode and anode.
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Controlled Experiment 3 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
An anode current collector (e.g., the current collector 110,
Next, a lithium metal foil with an area of about 38 mm×58 mm and a thickness of about 20 μm is placed on the Li7La3Zr2O12 scaffold layer. The scaffold layer and the lithium metal foil are placed in argon (Ar) atmosphere and heated to 300° C. Then a pressure of 0.01 MPa is applied to press the lithium metal foil towards the carbon film and held for 1 minute, to obtain a mixed composite layer (e.g., the composite layer 120,
Next, an insulation layer (e.g., the insulation layer 130,
Next, a protection layer (e.g., the protection layer 140,
Next, similar steps can be used to form the composite layer, the insulation layer, and the PEO protection layer on the opposite surface of the anode current collector to obtain a double-sided anode sheet as shown in
Cathode is formed by mixing cathode active material lithium cobalt oxide (LiCoO2), carbon conductive additive carbon black, and binders polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5. Solvent N-methylpyrrolidone (NMP) is added to homogeneously mix the powers to form a cathode slurry with a solid content of 75%. The cathode slurry is then homogeneously coated on an aluminum metal foil, and then baked-dry at 90° C. to obtain a cathode sheet. Then the cathode sheet is cut into 38 mm×58 mm dimensions to be used as cathodes (e.g.,
In a dry argon (Ar) atmosphere, the organic solvent ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a mass ratio of EC:EMC:DEC=30:50:20. Then a lithium salt lithium hexafluorophosphate (LiPF6) is added into the mixed organic solvent until completely dissolved and uniformly mixed to obtain an electrolytic solution having the lithium salt concentration of 1.15 M (mol/L).
To form a lithium ion battery as shown in
After stacking one or more pairs of cathode and anode, the four corners of the entire laminated structure are fixed by tape, and the laminated structure is placed in an aluminum plastic film. The aluminum film is then partially sealed from one or more sides, and electrolyte as prepared in Controlled Experiment 4 step (3) is injected into the battery. The electrolyte-soaked battery is further sealed and packaged to obtain a laminated lithium metal battery (or a laminated lithium ion battery).
[Tests of Lithium Ion Batteries Made from the Above Nine Embodiments and Four Controlled Experiments]
Lithium ion batteries prepared from the above nine Embodiments and four Controlled Experiments respectively were tested for (1) the changes of the anode thickness from before and after charging the lithium ion batteries to 4.2 V, and (2) the electrochemical performance, e.g., charge and discharge capacities, of the lithium ion battery.
To test the anode thickness change, first, an uncharged lithium ion battery prepared using a respective condition is disassembled, and the anode is removed and dried. A micrometer is used to measure the original thickness (D1) of the dried anode before charging.
Then, a lithium ion battery prepared using the same condition is charged to 4.2 V, and then disassembled. The charged anode is removed and dried. A micrometer is used to measure the thickness (D2) of the dried charged anode after charging.
The thickness increasing rate (Δt %) is determined by:
where Cu1 is the thickness of the copper current collector of the anode having the original thickness D1 in the lithium ion battery before charging, and Cu2 is the thickness of the copper current collector of the charged anode having the thickness D2 in the lithium ion battery after charging.
To test the charge and discharge capacities the lithium ion batteries prepared under different conditions, the batteries are tested between 3.7 V and 4.2 V, i.e., charged to 4.2 V and discharged to 3.7 V, at a current density of 0.15 mA/cm2.
The test results of the lithium ion batteries from the above nine Embodiments (Embt.) and four Controlled Experiments (C.E.) are listed in Table 1 below.
The porosities were determined based on 10 parallel samples prepared under a respective condition. Each sample is tested using a scanning electron microscope (SEM), to determine the pore distribution within a 1 mm×1 mm area. In particular, the porosity is determined to be the percentage of the area taken by the pores (i.e., the void areas without any materials) in the total area (i.e., 1 mm×1 mm area). The result is a valid number after the decimal point. When the number is less than 0.1%, it is recorded as 0.1%.
As shown in Table 1, the scaffold layer can preserve and support space for Li deposition after charging the lithium ion battery, so that the anode thickness does not increase drastically after charging the lithium ion battery. In particular, the scaffold layer has a porosity between 30% and 85%, and the ionic conductivity of the scaffold material is in a range from 10−2 to 10−8 S/cm. When the scaffold layer comprises the same material, the scaffold layer having a higher porosity has a weaker scaffold structure, which in turn has a weaker ability to confine thickness change of lithium metal, resulting in higher anode thickness increase rate after charging the battery. For example, PEO nanofiber scaffold with 85% porosity in Embodiment 1 has a bigger thickness increase than PEO nanofiber scaffold with 30% porosity in Embodiment 3.
In some embodiments, the insulation layer has a thickness in a range from 5 μm to 60 μm, and a width in a range from 0.5 mm to 10 mm. The material in the insulation layer does not conduct electrons or ions, and has a resistivity bigger than 107 Ω·m, preferably bigger than 1010 Ω·m.
The insulation layer in the composite anode as disclosed in the present application is configured to confine the Li+ ions diffusion and Li+ ions reduction/oxidation within a range defined by the insulation layer. This is because the insulation layer can effectively prevent direct contact between the current collector and the protection layer, so that electrons conducted within the current collector cannot directly contact or react with (e.g., reduce) Li+ ions diffused within the protection layer. Therefore, the insulation layer can confine the reduction of Li+ ions to Li metal to take place only in the composite layer. As an example demonstrated in the Controlled Experiment 3, when a lithium ion battery does not include an insulation layer in the anode, Li metal may be deposited on the cross-sectional edges of the battery, on the protection layer, and even beyond the region covered by the protection layer, which may significantly reduce the capacity retention (i.e., the discharge capacity after 30th cycle/discharge capacity after 1st cycle dropped to 55%).
In some embodiments, the protection layer has a thickness in a range from 0.1 μm to 30 μm, a porosity less than 5%, and a pore size smaller than 1 μm. In some embodiments, the material of the protection layer is capable of conducting ions, and has an ionic conductivity in a range from 10−2 to 10−8 S/cm.
The protection layer as discussed in the present disclosure can effectively block or significantly reduce the passage of electrolyte into the composite layer of the anode, so as to reduce the contact between lithium metal anode and electrolyte to avoid side reactions and increase the coulombic efficiency of the battery. The capacity retention can be significantly improved in a battery having a protection layer in the anode. For example, for the lithium ion battery having no protection layer in Controlled Experiment 2, after charging and discharging the battery for 30 cycles, essentially the battery has no capacity left.
The porosity and thickness of the protection layer are important to the performance of the lithium ion battery. For example, when the protection layer has sufficiently small porosity and pore size, the organic molecules in electrolyte cannot penetrate the protection layer to get in contact with the lithium metal, thus effectively avoiding side reactions between the electrolyte and the lithium metal, and improving capacity retention after charging and discharging the lithium ion battery for many cycles.
On the other hand, even if a battery includes a protection layer, when the porosity of the protection layer is too big, the electrolyte and the organic molecules can freely pass through the protection layer to react with the Li metal in the composite layer, thus significantly reducing the battery capacity retention. For example, for the lithium ion battery having a protection layer with a high porosity of 15.1% in Controlled Experiment 4, after charging and discharging the battery for 30 cycles, essentially the battery has no capacity left.
When the protection layer uses the same material, a thicker protection layer can effectively prevent electrolyte penetration and inhibit dendrite growth, thus providing a better strength and mechanical integrity after charging and discharging the battery for many cycles. However, Li+ ionic conductivity (or the ionic conductance) of the protection layer may decrease due to the increased thickness, which may increase battery polarization and reduce the battery performance. Thus a protection layer with a suitable thickness range, e.g., 0.1 μm to 30 μm, is beneficial to lithium ion battery for at least these reasons discussed herein.
The terminology used in the description of the embodiments herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of claims. As used in the description of the embodiments and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof.
It will also be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first electrode could be termed a second electrode, and, similarly, a second electrode could be termed a first electrode, without departing from the scope of the embodiments. The first electrode and the second electrode are both electrodes, but they are not the same electrode.
The description of the present application has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications, variations, and alternative embodiments will be apparent to those of ordinary skill in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. The embodiment was chosen and described in order to best explain the principles of the invention, the practical application, and to enable others skilled in the art to understand the invention for various embodiments and to best utilize the underlying principles and various embodiments with various modifications as are suited to the particular use contemplated. Therefore, it is to be understood that the scope of claims is not to be limited to the specific examples of the embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201910016479.0 | Jan 2019 | CN | national |
