Patent Application
20170121807
This disclosure pertains to the use of an atmospheric plasma for forming thin layers of electrode materials on a cell-member surface in the manufacture of cell components for lithium secondary batteries. More specifically, this disclosure pertains to methods of coating particles of anode materials and cathode materials with smaller particles of elemental metal, preparatory to depositing the metal particle coated-electrode material particles on a current collector layer or a porous separator layer. During deposition of the particles of electrode material by atmospheric plasma, the metal particles melt to bond the electrode particles to each other and to a cell member substrate in a porous layer for infiltration by a liquid lithium-ion containing electrolyte in an assembled cell. The metal coating also provides electrical conductivity to the anode or cathode layer.
Assemblies of lithium-ion battery cells are finding increasing applications in providing motive power in automotive vehicles. Lithium-sulfur cells are also candidates for such applications. Each lithium-ion cell of the battery is capable of providing an electrical potential of about three to four volts and a direct electrical current based on the composition and mass of the electrode materials in the cell. The cell is capable of being discharged and re-charged over many cycles. A battery is assembled for an application by combining a suitable number of individual cells in a combination of electrical parallel and series connections to satisfy voltage and current requirements for a specified electric motor. In a lithium-ion battery application for an electrically powered vehicle, the assembled battery may, for example, comprise up to three hundred individually packaged cells that are electrically interconnected to provide forty to four hundred volts and sufficient electrical power to an electrical traction motor to drive a vehicle. The direct current produced by the battery may be converted into an alternating current for more efficient motor operation.
In these automotive applications, each lithium-ion cell typically comprises a negative electrode layer (anode, during cell discharge), a positive electrode layer (cathode, during cell discharge), a thin porous separator layer interposed in face-to-face contact between parallel facing electrode layers, and a liquid, lithium-containing, electrolyte solution filling the pores of the separator and contacting the facing surfaces of the electrode layers for transport of lithium ions during repeated cell discharging and re-charging cycles. Each electrode is prepared to contain a layer of an electrode material, typically deposited as a wet mixture on a thin layer of a metallic current collector.
For example, the negative electrode material has been formed by depositing a thin layer of graphite particles, often mixed with conductive carbon black, and a suitable polymeric binder onto one or both sides of a thin foil of copper which serves as the current collector for the negative electrode. The positive electrode also comprises a thin layer of resin-bonded, porous particulate, lithium-metal-oxide composition bonded to a thin foil of aluminum which serves as the current collector for the positive electrode. Thus, the respective electrodes have been made by dispersing mixtures of the respective binders and active particulate materials in a suitable liquid, depositing the wet mixture as a layer of controlled thickness on the surface of a current collector foil, and drying, pressing, and fixing the resin bonded electrode particles to their respective current collector surfaces. The positive and negative electrodes may be formed on conductive metal current collector sheets of a suitable area and shape, and cut (if necessary), folded, rolled, or otherwise shaped for assembly into lithium-ion cell containers with suitable porous separators and a liquid electrolyte. But such processing of the wet mixtures of electrode materials requires extended periods of manufacturing time. And the thickness of the respective active material layers (which limits the electrical capacity of the cell) is limited to minimize residual stress during drying of the electrode material.
The preparation and deposition of the wet mixtures of electrode materials on current collector foils is now seen as time-consuming, cell capacity limiting, and expensive. It is recognized that there is a need for a simpler and more efficient practice for making layers of electrode materials for lithium-ion battery cells.
In a related, commonly-owned, patent application, PCT (CN 2013) 085330, filed 16 Oct. 2013, titled “Making Lithium Secondary Battery Electrodes Using an Atmospheric Plasma,” methods were disclosed for making lithium secondary battery electrode structures using an atmospheric plasma to deposit particles of electrode materials onto a selected substrate surface for the electrode structure and to bond the deposited particles to the substrate surface of the electrode structure. When the electrode material was a conductive metal, such as aluminum or copper, used to from a current collector film for an electrode, particles of the conductive metal were deposited on a selected substrate using the disclosed atmospheric plasma process. And when the electrode materials were non-metallic particles for an active electrode material, such as silicon, graphite, or lithium titanate, the non-metallic material particles were preferably coated with a metal or mixed with metal particles prior to deposition on a cell member substrate using the atmospheric plasma.
In accordance with practices of this invention, particles of non-metallic lithium-accepting and lithium-releasing materials for use in lithium-ion and lithium-sulfur electrode structures are coated with smaller particles of a suitable complementary conductive metal using an electroless coating or impregnation method. The conductive metal-coated, active electrode material particles are then deposited on a surface of a cell member using an atmospheric plasma source. Practices for applying submicron-size, elemental metal particles to small particles of non-metallic electrode material may be used to prepare the electrode particles in making anodes (negative electrodes) for lithium-ion cells and lithium-sulfur secondary cells, and they may be used in making cathodes (positive electrodes) for lithium-ion cells. The porous electrode structures are typically formed as thin layers of up to about two hundred micrometers in thickness. The metal particle-coated electrode particles are applied by using an atmospheric plasma to deposit a uniformly thick, porous layer of the particles, bonded to each other and to a porous ceramic or polymeric separator layer or to a metallic current collector layer.
In applications for making layered anode structures, the active material particles may, for example, be composed of one or more of silicon, silicon alloys, SiOx, Li—Si alloys, graphite, and lithium titanate (lithium meta-titanate, Li2TiO3). In accordance with practices of this invention, particles of non-metallic, active electrode material are prepared having a suitable particle size range for use in an electrode layer. For example, the non-metallic electrode material particles may have particle sizes in the range of about hundreds of nanometers to tens of micrometers, preferably in the range of about one micrometer to about fifty micrometers. Typically an elemental metal is applied in the form of sub-micron size particles on the surfaces of the particles of active electrode material. The coating of smaller metal particles, dispersed on the particles of active material, is to serve as a binder, by providing binding sites, and to provide suitable electrical conductivity in a layer of electrode material deposited in a substrate by atmospheric plasma application. The composition of the metal binder and electrical conductor is selected to be compatible with the electrochemical working potentials of the cathode or anode of a lithium secondary battery. In general, metals suitable as binder/conductors in lithium-ion anode electrodes include: copper, silver, and gold (Group 1B of the periodic table), nickel, palladium, and platinum (Group VIII), and tin (Group IVA). The composition of the conductive metal is selected and used in an amount to partially melt in the atmospheric plasma and to bond the electrode material particles as a porous layer to a current collector foil for lithium-secondary cell or to a porous separator layer for the cell. Upon re-solidification, the conductive metal provides binding sites that bond the electrode material particles to each other in a porous layer and to an underlying current collector or separator substrate. The conductive metal constituent is used in an amount to securely bond the active electrode material particles to the cell-member substrate as a porous layer that can be infiltrated with a liquid electrolyte to be used in an assembled lithium-ion cell. Further, the conductive metal also provides electrical conductivity to the deposited layer of electrode material. Typically, the particles of conductive metal may be applied in an amount of from about five weight percent to about sixty weight percent of the total weight of the composite of metal and active material constituent(s). In accordance with practices of this invention, the conductive metal/active electrode material particle composition consists exclusively of such metal particle site bound-active material for the electrode, free of any liquid vehicle or organic binder material.
Similarly, and separately, particles of positive electrode materials, such as lithium-manganese-oxide, lithium-nickel-oxide, and/or lithium-cobalt-oxide are coated with metal particles by an electroless coating or impregnation method. Metals suitable as particle-site binder/conductors in lithium-ion cathode electrodes include: aluminum, indium, and thallium (Group IIIA), titanium, zirconium, and hafnium (Group IVB), nickel, palladium, and platinum (Group VIII), and silver and gold (Group IB). Preferably, sub-micron-size particles of the selected metal are deposited on particles of the non-metallic active electrode material by an electroless coating or impregnation method.
In one exemplary electroless deposition process for the formation of lithium-ion cell anode material, an aqueous solution of a metal salt (such as copper sulfate or copper nitrate) is combined with a cation complex-forming agent such as ethylene diamine tetraacetic acid (EDTA). The complex is de-stabilized and chemically reduced to deposit submicron size elemental copper particles on particles of a selected anode material such as lithium titanate.
In another suitable electroless impregnation method, a solution is prepared of a suitable metal salt (such as a solution of copper nitrate in ethanol). Particles of active electrode materials are wetted with the solution to coat each particle of electrode material. Particles of metal salt are deposited on the particles of the active electrode material by evaporation of the solvent (e.g., ethanol). The metal salt coated electrode material particles are annealed in air to form metal oxide particles. And the metal oxide particles are reduced in hydrogen to form active material particles coated with sub-micron sized elemental metal particles.
Electrode material/conductor particles of suitable micron-size are then supplied or delivered (for example) by gravity into a gas stream, such as an air stream or a stream of nitrogen or an inert gas, flowing within an upstream tubular delivery tube of an atmospheric plasma generator. The particles are preferably delivered through a powder management device to ensure stable and consistent delivery of the electrode material/conductor particles into the gas stream. As stated, the particles may consist, for example, of copper-coated, silicon-containing particles for forming an anode layer for a lithium-ion cell. The two-component particles are dispersed into the gas stream and carried into the nozzle of the plasma generator where the flowing gas molecules are momentarily converted into plasma by a suitable electrical discharge at the nozzle outlet. The plasma heats the moving dispersed particles to soften and partially melt the coating of metallic, electrical conductor particles. For example, sites of small droplets of molten metal are formed on the surfaces of the electrode material particles. As the particle mixture is deposited on the surface of an unheated substrate, the liquefied metal coating sites re-solidify to bond the active electrode material particles to each other in a porous layer and the metal bonds the particles at the facing surface of the particulate layer to the substrate surface.
The atmospheric plasma stream is directed against the substrate surface in, for example, a suitable sweeping path so as to deposit the active electrode material as a porous layer of conductive metal-bonded particles adhering to the cooperating metal foil substrate. Either, or both, of the plasma and substrate may be in motion during the deposition of the active electrode material. In many applications of the process, the electrode material layer will be deposited in one or more coating steps with a total uniform thickness of up to about 200 micrometers. The thickness of the deposit of active electrode material usually depends on the intended electrical generating capacity of the cell.
The electrodes function upon suitable contact of the electrode material by the electrolyte and transfer of lithium into and from each electrode during the cycling of the cell.
In general, atmospheric plasma deposition practices of the invention may be conducted under ambient conditions and without preheating of either the substrate layer or the solid particles carefully supplied to the atmospheric plasma generator.
Although the coating particles are momentarily heated in the high temperature atmospheric plasma, they are typically deposited on the substrate material without heating the substrate to a temperature as high as 150° C.
Other objects and advantages of the invention will become apparent from the further illustrations of practices of the invention in the following sections of this specification.
An active lithium-ion cell material is an element or compound which accepts or intercalates lithium ions, or releases or gives up lithium ions in the discharging and re-charging cycling of the cell. A few examples of suitable electrode materials for the anode (or negative electrode) of a lithium ion cell are graphite, silicon, alloys of silicon with lithium or tin, silicon oxides (SiOx), and lithium titanate. Examples of cathode (or positive electrode) materials include lithium manganese oxide, lithium nickel oxide, lithium cobalt oxide and other lithium-metal-oxides. Other materials are known and commercially available. One or more of these materials may be used in an electrode layer. In accordance with practices of this invention, as will be described in more detail below in this specification, the respective electrode materials are initially in the form of micron size particles (e.g., about one to about fifty microns in largest dimension) that are coated by an electroless coating or impregnation method with smaller particles of electrically conductive, elemental metal. For example, copper particles up to about five micrometers in maximum dimension have been deposited by an electroless coating or impregnation method on lithium titanate particles up to about fifty micrometers in largest dimension.
An illustrative lithium-ion cell will be described, in which electrode members can be prepared using practices of this invention.
In
Deposited on the negative electrode current collector 12 is a thin, porous layer of negative electrode material 14. As illustrated in
A positive electrode is shown, comprising a positive current collector foil 16 (often formed of aluminum) and a coextensive, overlying, porous deposit of positive electrode material 18. Positive current collector foil 16 also has a connector tab 16′ for electrical connection with other electrodes in other cells that may be packaged together in the assembly of a lithium-ion battery. The positive current collector foil 16 and its coating of porous positive electrode material 18 are typically formed in a size and shape that are complementary to the dimensions of an associated negative electrode. In the illustration of
A thin porous separator layer 20 is interposed between the major outer face of the negative electrode material layer 14 and the major outer face of the positive electrode material layer 18. In many battery constructions, the separator material is a porous layer of a polyolefin, such as polyethylene or polypropylene. Often the thermoplastic material comprises inter-bonded, randomly oriented fibers of PE or PP. The fiber surfaces of the separator may be coated with particles of alumina, or other insulator material, to enhance the electrical resistance of the separator, while retaining the porosity of the separator layer for infiltration with liquid electrolyte and transport of lithium ions between the cell electrodes. The separator layer 20 is used to prevent direct electrical contact between the negative and positive electrode material layers 14, 18, and is shaped and sized to serve this function. In the assembly of the cell, the opposing major outer faces of the electrode material layers 14, 18 are pressed against the major area faces of the separator membrane 20. A liquid electrolyte is injected into the pores of the separator membrane 20 and electrode material layers 14, 18.
The electrolyte for the lithium-ion cell is often a lithium salt dissolved in one or more organic liquid solvents. Examples of salts include lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), and lithium trifluoroethanesulfonimide. Some examples of solvents that may be used to dissolve the electrolyte salt include ethylene carbonate, dimethyl carbonate, methylethyl carbonate, propylene carbonate. There are other lithium salts that may be used and other solvents. But a combination of lithium salt and liquid solvent is selected for providing suitable mobility and transport of lithium ions in the operation of the cell. The electrolyte is carefully dispersed into and between closely spaced layers of the electrode elements and separator layers. The electrolyte is not illustrated in the drawing figure because it is difficult to illustrate between tightly compacted electrode layers.
In accordance with embodiments of this invention, atmospheric plasmas are used in the manufacture of electrode members of lithium-ion cells. And in accordance with practices of this invention, particles of an active electrode material are coated with smaller particles of a suitable complementary elemental metal (or mixtures of elemental metals) for use in the atmospheric plasma deposition process. For example, anode materials may be prepared for use in lithium-ion cells and lithium-sulfur cells by coating practices of this invention. And cathode materials may be prepared for lithium-ion cells.
As described above in this specification, anodes for lithium-ion cells are often made by placement of a porous lithium titanate material on a copper foil current collector. And cathodes for lithium-ion cells are often made by placement of a porous lithium cobalt oxide layer on an aluminum foil current collector. In accordance with this invention, particles of lithium titanate are coated with smaller particles of copper and the copper-coated lithium titanate particles are applied to a surface of a copper current collector or to a surface of a porous separator. In a similar manner, particles of lithium cobalt oxide are coated with particles of aluminum and applied to a surface of an aluminum current collector or to a surface of a porous separator.
In this example, the method is applied to deposit copper particles on particles of lithium titanate. In
In this example, Cu(NO3)2.3H2O was dissolved in pure ethanol to form a solution containing two moles per liter of copper. The solution of copper salt was soaked onto a porous mass of the electrode particles in a suitable container, and the alcohol is evaporated at ambient temperature to leave a coating of 1.18 grams of the copper salt, Cu(NO3)2, 32 in
The above-described copper nitrate-coated lithium titanate particles were initially heated in air from room temperature to 150° C. at a rate of 5 C/minute. The mixed particles were then heated in air from 150° C. to 400° C. at a rate of 1 C/min. The mixed particles were held in air for five hours at 400° C., and then air cooled to room temperature. The copper nitrate deposit on the lithium titanate particles 30 was thus converted to particles 36 of copper oxide (CuO) on lithium titanate particle 30 in
The copper oxide particles 36 on the lithium titanate particle 30 were reduced in a hydrogen atmosphere, as follows, to form lithium titanate particles 30 coated with sub-micron sized elemental copper particles 36 as illustrated in
The illustration of
In general, a suitable, electrochemically compatible conductive elemental metal is selected for deposition on the surfaces of suitably-sized particles of active lithium-ion electrode material. An inorganic or organic compound of the metal and a solvent are selected for soaking and dispersing the metal compound onto the particles of the active electrode material. In general, a metal salt which can readily be converted into the metal oxide is preferred. And a solvent is selected which will dissolve an appreciable amount of the metal compound for obtaining a suitable amount of the metal compound on the particles of active material. After removing the solvent to deposit the selected metal compound on the active material particles, the metal is oxidized by a suitable oxidation process, analogous to that described for the copper nitrate. Then the metal oxide is reduced with hydrogen to leave small particles of the conductive elemental metal on the surfaces of the particles of active electrode material.
In another exemplary electroless deposition process for the formation of lithium-ion cell anode material, an aqueous solution of a metal salt (such as cupric sulfate) is combined with a cation complex-forming agent such as ethylene diamine tetraacetic acid (EDTA). The complex is de-stabilized in the presence of a suitable reducing agent to deposit submicron size elemental copper particles on particles of a selected anode material, such as lithium titanate. For example, an aqueous solution of 0.04 M CuSO4 and 0.04M EDTA is prepared and mixed with an amount of lithium titanate to obtain a desired amount of coating with copper particles. Sodium hydroxide is added to the aqueous solution to achieve a pH of 12 and the mixture is heated to about 70° C. An aqueous formaldehyde solution (8 mmol) or the equivalent amount of solid paraformaldehyde is added to the aqueous dispersion with lithium titanate particles. The liquid-solid system is purged with a stream of nitrogen. After the addition of the formaldehyde reductant and the nitrogen streaming for about three to five hours, the lithium titanate particles, now coated with copper particles were collected by filtration, washed with an abundance of water and dried. The resultant solid mixture is elemental copper particle-coated lithium titanate particles.
Other chelating agents for the deposition of elemental metals on particles of active electrode particles include sodium citrate, Quadrol® [N,N,N′,N′-tetrakis (2-hydroxypropyl) ethylenediamine], Rochelle salts (potassium sodium tartrate), and EDTA with an alkanolamine, particularly triethanolamine. In addition to formaldehyde, suitable reducing agents for use with the chelate agent-complexed metal salt are hypophosphite, borohydride, hydrazine, glyoxalic acid, and amine-boranes. Many metals may be electroless coated by such complexation of a salt and reduced. They include, for example, copper, nickel, tin, and gold.
In an exemplary electroless coating or impregnation method for the formation of lithium-ion cell cathode material, a metal salt, such as aluminum chloride, is dissolved in an ionic liquid such as 1-ethyl-3-methylimidizolium chloride (EMIC). The solution is destabilized in the presence of a suitable reducing agent to deposit submicron size elemental aluminum particles on particles of a selected cathode material, such as lithium manganese oxide (LMO). For example, 0.04 mol of AlCl3 and 0.02 mol of EMIC were mixed by stirring. An aluminum wire was then immersed in the liquid for a period of time (e.g., a period of 168 hours) to purify the liquid and to obtain a colorless and transparent ionic liquid. The ionic liquid was then mixed with an amount of lithium manganese oxide particles to obtain a coating of submicron-sized aluminum particles on the cathode material particles. Diisobutyl aluminum hydride (DIBAH), a reducing agent, was added, with a stream of flowing argon, to the mixture of aluminum-containing ionic liquid and small LMO particles. After a reaction period of about three to five hours, the LMO particles, now coated with submicron aluminum particles, are collected by filtration, washed with ethanol, and dried. The resultant material is lithium manganese oxide particles coated with submicron particles of elemental aluminum. The mixture may be deposited using an atmospheric plasma on a lithium-ion battery substrate layer, such as a cathode current collector foil or a battery separator layer.
Other ionic liquids to dissolve an aluminum salt (e.g., AlCl3) include 1-alkyl-3-methylimidazolium chlorides such as 1-butyl-3-methylimidazolium chloride (BMIC), and alkyl pyridinium chlorides such as n-butyl pyridinium chloride (BPC). Other suitable reducing agents include LiH, LiAlH4, and NaBH4.
Elemental metal particle-coated electrode material particles are thus ready for deposition on a lithium cell substrate member in a battery electrode-making process using an atmospheric plasma source. In many practices, the metal-coated electrode material is deposited on a current collector substrate using atmospheric plasma. The resulting electrode may then be stacked with a separator member and combined with an opposing electrode member, made using a complementary metal coated electrode material. In another practice, metal particle coated electrode material particles may be deposited on a porous separator member using atmospheric plasma. And a layer of current collector material may be deposited to the upper side of the deposited electrode material.
The total coating thickness can reach up to a few hundred microns depending on the electrode materials used and plasma processing conditions. Its wide thickness range makes the process versatile for both energy and power cell applications. In contrast to the current wet-transfer coating method of making battery electrodes, by eliminating the need for slurry, wet coating, drying and pressing processes, cell manufacturing cycle time and cost can be greatly reduced.
Atmospheric plasma spray methods are known and plasma spray nozzles are commercially available. In practices of this invention, and with reference to
The stream of air-based plasma and suspended electrode particle material 60 is progressively directed by the nozzle against the surface of a substrate, such as a metal current collector foil 116 for a positive electrode for a lithium-ion cell. The substrate foil 116 is supported on a suitable working surface 62 for the atmospheric plasma deposition process. The deposition substrate for the atmospheric plasma deposition is illustrated in
In embodiments of this invention, the two-component particulate material (58 in
Such plasma nozzles for this application are commercially available and may be carried and used on robot arms, under multi-directional computer control, to coat the many surfaces of each planar substrate for a lithium-ion cell module. Multiple nozzles may be required and arranged in such a way that a high coating speed may be achieved in terms coated area per unit of time.
The plasma nozzle typically has a metallic tubular housing which provides a flow path of suitable length for receiving the flow of working gas and dispersed particles of electrode material and for enabling the formation of the plasma stream in an electromagnetic field established within the flow path of the tubular housing. The tubular housing terminates in a conically tapered outlet, shaped to direct the shaped plasma stream toward an intended substrate to be coated. An electrically insulating ceramic tube is typically inserted at the inlet of the tubular housing such that it extends along a portion of the flow passage. A stream of a working gas, such as air, and carrying dispersed particles of metal particle-coated electrode material, is introduced into the inlet of the nozzle. The flow of the air-particle mixture may be caused to swirl turbulently in its flow path by use of a swirl piece with flow openings, also inserted near the inlet end of the nozzle. A linear (pin-like) electrode is placed at the ceramic tube site, along the flow axis of the nozzle at the upstream end of the flow tube. During plasma generation the electrode is powered by a high frequency generator at a frequency of about 50 to 60 kHz (for example) and to a suitable potential of a few kilovolts. The metallic housing of the plasma nozzle is grounded. Thus, an electrical discharge can be generated between the axial pin electrode and the housing.
When the generator voltage is applied, the frequency of the applied voltage and the dielectric properties of the ceramic tube produce a corona discharge at the stream inlet and the electrode. As a result of the corona discharge, an arc discharge from the electrode tip to the housing is formed. This arc discharge is carried by the turbulent flow of the air/particulate electrode material stream to the outlet of the nozzle. A reactive plasma of the air and electrode material mixture is formed at a relatively low temperature. A copper nozzle at the outlet of the plasma container is shaped to direct the plasma stream in a suitably confined path against the surfaces of the substrates for the lithium-ion cell elements. And the plasma nozzle may be carried by a computer-controlled robot to move the plasma stream in multi-directional paths over the planar surface of the substrate material to deposit the electrode material in a continuous thin layer on the thin substrate surface layer. The deposited plasma-activated material forms an adherent porous layer of bonded electrode material particles on the current collector foil surface.
In the example illustrated in
Also, two different active materials (varying in composition and/or morphology) may be co-deposited, one from each of two or more different delivering tubes supplying the plasma nozzle. This provides flexibility to the electrode material forming process by changing electrode material compositions from one layer to another in the plasma delivery process to change electrode properties in different layers of a multi-layer deposit on a substrate.
As stated, a suitable non-electrically conductive, porous separator layer may be used as a substrate. The atmospheric plasma coating deposit does not get so hot as to damage a polymeric separator if one is used as a substrate. Electrode materials may be deposited on the separator membrane substrate in a suitable pattern. And a current collector layer may be deposited by atmospheric plasma in a suitable pattern on the electrode material layer.
Thus, methods of using atmospheric plasma have been provided to form layered electrode materials and current collectors for working electrodes and reference electrodes in lithium-ion cells. The plasma method enables the formation of working material layers of up to about two hundred micrometers in thickness to increase the capacity of the electrodes. And the process avoids the use of extraneous binders of polymers and the need for wet process application of electrode materials to their current collector substrates.
It is recognized that the use of an atmospheric plasma may also be utilized in forming anode materials for lithiated silicon-sulfur secondary batteries. Lithiated silicon-sulfur cells typically comprise a lithiated silicon-based anode, a lithium polysulfide electrolyte, a porous separator layer and a sulfur-based cathode. A layer of silicon based materials, including, for example, silicon, silicon alloys, and silicon-graphite composites, up to about 200 microns in thickness is deposited on a metal current collector in the formation of an anode layer. Atmospheric plasma deposition processes, like those described for the preparation of layered electrode members of lithium-ion cells may be used in making analogous electrode structures for lithiated silicon-sulfur cells.
The examples that have been provided to illustrate practices of the invention are not intended as limitations on the scope of such practices.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2014/074596 | 4/2/2014 | WO | 00 |
