Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/04—Construction or manufacture in general
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/04—Construction or manufacture in general
  • H01M10/0436—Small-sized flat cells or batteries for portable equipment
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/06—Lead-acid accumulators
  • H01M10/12—Construction or manufacture
  • H01M10/126—Small-sized flat cells or batteries for portable equipment
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/24—Alkaline accumulators
  • H01M10/28—Construction or manufacture
  • H01M10/287—Small-sized flat cells or batteries for portable equipment
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M6/00—Primary cells; Manufacture thereof
  • H01M6/04—Cells with aqueous electrolyte
  • H01M6/06—Dry cells, i.e. cells wherein the electrolyte is rendered non-fluid
  • H01M6/12—Dry cells, i.e. cells wherein the electrolyte is rendered non-fluid with flat electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/70—Carriers or collectors characterised by shape or form
  • H01M4/72—Grids
  • H01M4/74—Meshes or woven material; Expanded metal
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• This invention relates generally to batteries comprising one or an integrated series of polymer matrix bi-cell batteries.
• Each individual bi-cell comprises, sequentially, a first counter electrode, a film separator, a central electrode, a film separator, and a second counter electrode.
• a lithium ion electrolytic cell such as a rechargeable lithium ion battery, is commonly constructed by means of the lamination of electrode and separator film cell elements which are individually prepared. Each of the electrodes and the film separator is formed individually, for example by coating, extrusion, or otherwise, from compositions including binder materials and a plasticizer.
• Lithium ion electrolytic cells 101 may be of the traditional type, shown in Figure 1, with an cathode 110, a separator 112, and an anode 114 sandwiched together.
• a separator is positioned between a negative electrode and a positive electrode.
• the anode, separator, and cathode structures are then laminated to produce a standard unitary flexible electrolytic cell precursor structure .
• the precursor can be extracted and activated with electrolyte to form a functional battery.
• a lithium ion battery typically comprises several solid, secondary electrolytic cells in which the current from each of the cells is accumulated by a conventional current collector, so that the total current generated by the battery is roughly the sum of the current generated from each of the individual electrolytic cells employed in the battery. In lithium ion batteries it is common to stack separate electrolyte cells to create the battery.
• Bi- cells are more complex than standard cells, and require the successful lamination of more layers.
• a bi-cell 201 for example that shown in Figure
• first counter electrode 214a having a first medially positioned current collector 215a, a first separator 212a, a central electrode 210 having a centrally located current collector 215a, a second separator 212b, and a second counter electrode
• the counter electrodes 214a and 214b are cathode (positive electrode) and the central electrode 210 is the anode (negative electrode) .
• FIG. 2b shows an exploded graphic representation of the interface between at a current collector.
• the current collectors used are grids or perforated sheets 255, which permit a direct contact interface region 248 between two sheets of polymer electrode 253a, 253b. This electrode- electrode contact across the perforated current collector has proven to be critical in producing bi-cells which resist delamination during use.
• a battery achieve the maximum energy potential and cycle life. It would therefore be preferred that the current collector in the anodic and cathodic electrode be positioned to provide optimum battery performance.
• the placement of the current collector within the counter electrodes can affect the electrochemical properties of the electrolytic cell.
• the positioning of the current collector within the counter electrode can be varied as desired within the outer half of the counter electrode. Improved battery performance is achieved in a bi-cell battery when the current collector of the counter electrodes are not positioned medially within the electrode, as with the prior art, or within the inner half, but are placed toward the outside of the counter electrodes, i.e., further removed from the central electrode Optimally, current collectors are positioned at the outermost edges of the two counter electrodes .
• Counter electrode materials are preferably attached to another film of similar material through the perforated current collector. When some percentage of the counter electrode material is external to the current collector, the counter electrode bonds to itself through the current collector grid.
• An optimal placement of the current collector in the counter electrode is at the outermost edge of a counter electrode, with 100% of the electrode material between the current collector and the central electrode. However, if all of the counter electrode is at one side of the current collector with no material at the opposite side of the current collector to which to bond during lamination, the counter electrode tends to delaminate relatively quickly, destroying battery life.
• Figure 1 shows a cross-sectional view of an electrolytic cell, including an electrode, a separator, and a counter electrode.
• Figure 2a shows a cross-sectional view of a bi- cell, including first and second counter electrodes, first and second separators, and a central electrode.
• Figure 2b shows an enlarged view of the interface between two films of a counter electrode material which bond through the gaps of the current collector grid.
• Figure 3 shows a cross-sectional view of an anode-out bi-cell, including first and second anodes, first and second separators, and central cathode.
• Figure 4 shows a cross-sectional view of a bi- cell having improved current collector placement in accordance with the invention herein.
• Figure 5 graphically represents a testing embodiment of a bi-cell, in which a prior art counter electrode and an improved counter electrode of the subject invention are simultaneously and competitively tested for charge and discharge.
• Figures 6 and 7 show results obtained when the counter electrodes are cathodic, during charge and discharge, respectively.
• Figures 8 and 9 show results obtained when the counter electrodes are anodic, during charge and discharge, respectively.
• the figures are drawn for clarity and are not drawn to scale. Similar numbers refer to similar structures .
• a traditional polymer matrix electrochemical cell has a negative electrode, a positive electrode, and a separator (generally a polymeric electrolyte film) therebetween.
• An ion-conducting electrolyte provides ion transfer from one electrode to the other, and commonly permeates the porous structure of each of the electrodes and the separator.
• Bi-cells include a central electrode (either cathode or anode) , with opposing counter electrodes present on each side of the central electrode, with each counter electrode separated from the central electrode by membrane or separator layers.
• the bi-cell is laminated under heat and pressure to provide good contact between the battery layers.
• central electrode refers to an electrode, either anode or cathode, which is centrally located in an individual bi-cell.
• counter electrode refers to an electrode which completes the electrochemical pair with the central electrode. In a bi-cell, there is a single central electrode and two counter electrodes. If the central electrode is an anode, the counter electrodes are cathodic . If the central electrode is a cathode, the counter electrodes are anodic.
• Each laminated component of the lithium ion polymer matrix battery herein is generally planar in configuration.
• the polymer matrix electrodes herein include a generally planar grid or perforated current collector as part of the electrode structure.
• the general plane of the current collector is paralleled by the general plane of the polymer matrix film portion of the electrode.
• the separator films are largely parallel in orientation to the electrodes.
• the current collector 211 of the central electrode 210 is both medially located within the central electrode and centrally located within the bi- cell.
• the current collectors 215a, 215b of the counter electrodes 214a, 214b are each medially located within their respective counter electrode, but are each located toward the outer edges of the bi-cell 201.
• each discrete functional layer within the bi-cell similarly includes an "inner” (toward the center of the bi-cell) and an “outer” (toward the outside of the bi-cell) region parallel to the general plane of both the specific discrete element and the bi- cell structure.
• the inner half will be located proximal to the central electrode, and the outer half will be located distal to the central electrode.
• “Half” refers to approximately 50% by weight of the counter electrode active material.
• One of the more difficult parameters in manufacturing polymer matrix batteries is the lamination of the various battery components to form a completed battery.
• Materials having a similar polymer matrix structure can be laminated together more easily than can dissimilar materials.
• Lamination of polymer matrix materials to the current collector grids have proven to be particularly problematic.
• a variety of adhesion promoters and lamination techniques have been tried with varying long-term success.
• a centrally located current collector within an electrode provides consistent lamination results with polymer matrix to polymer matrix bonding through the current collector grid.
• grid 315 placement on the inner surface 314i of the counter electrode is possible, sandwiching the grid 315 between the counter electrode 314 and the separator film 312.
• this placement provides poor battery efficiency.
• Figure 3b shows a similar arrangement wherein approximately 25% of the counter electrode 314 is located centrally to the current collector 315, sandwiched between the current collector and the separator film 312. The remaining 75% of the counter electrode is located outside the current collector. This embodiment does not demonstrate improved efficiency when compared to traditional embodiments.
• Figure 3c shows a reciprocal embodiment to that of Figure 3b. Specifically, approximately 75% of the counter electrode 314 is located centrally to the current collector 315, sandwiched between the current collector and the separator film 312. The remaining 25% of the counter electrode is located outside the current collector. This embodiment demonstrates improved efficiency when compared to traditional embodiments. Additionally, as there is polymer matrix on both sides of the current collector, lamination of the battery assembly is not impaired by the grid placement.
• Figure 3d shows an embodiment in which the current collector 315 is located at the outermost surface 314o of the counter electrode 314.
• the separator film 312 is located opposite the current collector grid 315.
• This embodiment provides optimized electrical performance when compared to the embodiments shown in Figures 3a-c. Due to the lamination of the electrode polymer matrix on a single side only of the current collector, however, the bi-cell is difficult to laminate and tends to delaminate relatively quickly. Delamination destroys battery function. Therefore, this embodiment optimizes battery efficiency but may compromise battery life.
• the preferred embodiment includes a centrally located separator film 312 adjacent the counter electrode 314.
• the current collector 315 is located on the outer surface 314o of the counter electrode 314.
• a polymer matrix film 313 is positioned outside the current collector 315 and laminated in position. The polymer matrix material bonds through the current collector grid to the counter electrode material during the lamination process.
• This embodiment optimizes batter efficiency and life, but results in a somewhat thickened bi-cell structure. It is most preferred that counter electrode 314 is the anode in a preferred "anode- out " arrangement .
• a certain amount of polymer matrix be present outside the current collector in the counter electrodes. If the polymer matrix is electrode material, it will generally be preferred that the amount outside the current collector be minimized within manufacturing parameters. For example, if electrode material is made in sheets having a predetermined thickness, one sheet may be placed outside the current collector, and multiple sheets can be positioned inside the current collector to form the counter electrode. A ratio of 1:2 occurs when one sheet of electrode film is laminated outside the current collector and two sheets of electrode film are laminated central to the current collector. A ratio of 1:3 is shown in Figure 3c. Ratios of one to four and greater are possible, varying with battery design and functionality parameters. The thickness of the portion of the electrode which is outside the current collector is not critical as long as battery capability and durability requirements are met.
• the specific thickness of the polymer matrix film is not critical as long as a good laminate bond can be formed.
• the same film which is used as the separator film can be used as the polymer matrix film. This has the advantage of using a material which is already produced for battery use in a new function. It is also advantageous because lamination requirements for separator film are known and can be applied as known in the art .
• a binder material provides a polymeric matrix for each of the central electrode, the separator membranes, and the counter electrodes.
• Each of the anodic and cathodic electrodes are formed by similar processes, but include specific anode- active or cathode-active materials in the polymeric binder. That is, a solid polymeric matrix provides part of the structure of the electrode.
• the preferred separator material is a polymeric matrix film which does not include electrode active materials.
• the preferred polymer matrix film for use when the current collector is located at the extreme edge of a counter electrode is a polymeric matrix film such as that which forms the separator.
• Polyvinylidene difluoride (PVdF) and hexafluoropropylene (HFP) copolymers are common binder materials, and are the binder materials which are generally useful in the subject invention.
• the copolymer generally comprises about 75 to 92% (by weight) of the PVdF, and about 8 to 25% HFP.
• the copolymer comprises about 85 to 90% of the PVdF, and about 10 to 15% HFP.
• One especially preferred, commercially available copolymer material is KYNARTM Flex 2801 (Elf Atochem North America, Philadelphia, PA) , which provides an 88:12 ratio of PVdF: HFP.
• Inorganic filler adjuncts such as fumed alumina or fumed silica, are added as desired to provide structural stability to the binder and provide a film having desirable qualities.
• a separator membrane may be a commercially available separator made of glass fiber, porous polypropylene or porous polyethylene .
• Such separators include Type A/E glass fiber filters (Gelman Sciences, Ann Arbor, MI), and Celgard (Hoechst-Celanese Corp.,
• the separator is preferably a solid polymeric matrix, such as the polymeric membrane described above .
• Such separator membranes are known to the art .
• Preferred polymeric electrolyte membranes are produced using a casting process in which a carrier liquid is removed to form a flexible sheet.
• An alternate preferred method produces polymeric electrolyte membranes by extrusion processes.
• Suitable polymeric electrolyte membranes provide a porous polymer matrix structure, permeated with a plasticizer, upon casting or curing.
• a plasticizer is an organic solvent that facilitates the formation of porous polymeric structures.
• Appropriate plasticizers have high boiling points, typically in the range from about 150° to about 350° C.
• the plasticizer or plasticizer system must be compatible with the components of the electrochemical cell precursor, it must be processable within design parameters, and it must exhibit low polymer solubility.
• the plasticizer may be subsequently removed (for example, by extraction) prior to the formation of the activated electrolytic cell.
• plasticizers for processing or activation of the battery precursor are known to the art.
• Such materials include, for example, ethylene carbonate (EC) ; ethyl propionate (EP) ; propylene carbonate (PC) ; butylene carbonate (BC) ; vinlyene carbonate (VC) ; dimethyl adipate (DMA) ; diethyl carbonate (DEC) ; dipropylene carbonate (DPC) ; dibutyl carbonate (DBC) ; acetates; diesters; oxalates such as dimethyl, succinate, adipate, suberate, and sebacate oxalates; glymes; and low molecular weight polymers such as polycarbonates, polyacrylates, polyesters or polysiloxanes .
• EC ethylene carbonate
• EP ethyl propionate
• PC propylene carbonate
• BC butylene carbonate
• VVC vinlyene carbonate
• DMA dimethyl adipate
• DEC diethyl carbonate
• DPC diprop
• plasticizers include dimethyl, diethyl, dipropyl, dibutyl, and dioctyl adipate.
• dibutyl phthalate (DBP) is a preferred plasticizer. Mixtures of such plasticizers can also be used.
• An electrode film forming material includes a binder, appropriate electrode active (anode-active or cathode-active) materials, a plasticizing solvent and, if appropriate, a casting solvent. Upon removal of casting solvent from the electrode film forming material, an electrode film is formed. Suitable electrode films provide a flexible sheet having a porous electrode-active structure, permeated with a plasticizer, after solvent casting.
• the negative electrode is the anode during discharge.
• Typical anode active materials are well known in the art, and include, by way of example, intercalation based anodes such as those using carbon or tungsten oxides, and the like.
• Anode active materials which are appropriate for use within the subject method include lithium intercalation anodes employing carbon materials such as graphite, cokes, mesocarbons, and the like.
• the anode may also include an electron conducting material such as carbon black.
• the anode includes a current collector laminated with the negative electrode material.
• Materials suitable for anodic current collectors are known to the art, and are usually comprised of an electron conductive material such as metals or alloys.
• Typical materials include nickel, iron, stainless steel, or copper.
• a copper foil sheet, open mesh, expanded metal, woven or non-woven or knitted wire fabric or grid is used.
• Each current collector is also connected to a current collector tab which extends from the edge of the current collector.
• the anode tabs are preferably electrically connected together (such as by welding) and connected to a copper or nickel lead. External loads can be electrically connected to the leads.
• Current collectors and tabs are described in U.S. Patents 4,925,752; 5,011,501; and 5,326,653; each of which is incorporated herein.
• An adhesion promoter can be used to facilitate bonding between the anode material and the anodic current collector.
• the positive electrode is the cathode during discharge.
• Many cathode active materials are known to the art, and include insertion compounds, i.e., any material which functions as a positive pole in a solid electrolytic cell. For lithium ion applications, these are normally characterized as containing all the lithium for the cell.
• Preferable cathodic materials de- intercalate lithium at a high voltage when contrasted to lithium, making them stable in air.
• Typical cathodic materials include, by way of example, transition metal oxides, sulfides, and selenides .
• Such materials include oxides of cobalt, manganese, molybdenum, and vanadium; sulfides of titanium, molybdenum, and niobium; the various chromium oxides; copper oxides; and lithiated oxides of cobalt, manganese and nickel; and the like.
• Cathodic materials include LixMn204, LiCo02, LiNi02 , LiCoO .5Ni0.5O2, and the like.
• the cathodic material is mixed with an electroconductive material such as graphite, powdered carbon, powdered nickel, metal particles, conductive polymers, and the like.
• the cathode is preferably produced using a polymeric binder to form the positive cathodic film, i.e., a solid polymeric matrix provides part of the structure of the cathode.
• the polymeric binder is formed using both a solid-polymer-forming material and a plasticizer compound.
• the cathode includes a current collector laminated with a positive electrode active film material.
• Materials suitable for cathodic current collectors are known to the art, and are typically comprised of an electron conductive material such as metals or alloys.
• the cathode current collector is typically of aluminum, stainless steel, and such foils having a protective conductive coating foil.
• the cathode current collector is an aluminum foil sheet, open mesh, expanded metal, woven or non-woven or knitted wire fabric or grid.
• Each current collector is also connected to a current collector tab which extends from the edge of the current collector.
• the cathode tabs are preferably welded together and connected to a lead. External loads can be electrically connected to the leads.
• An adhesion promoter can be used to facilitate bonding between the cathode material and the cathodic current collector.
• the laminate bi-cell 401 comprising, sequentially, a first counter electrode 414a having a current collector 415a at its outermost surface; a first separator element 412a; a central electrode 410 having a medially positioned current collector 411; a second separator element 412b; and a second counter electrode 414b having a current collector 415b at its outermost surface .
• Varying the position of the current collector within the counter electrodes varies the current distribution. It is possible that a position within the inner half of the counter electrode would be desirable. More preferable, however, is to position of the current collector within the outer half of the counter electrode.
• a preferred embodiment includes the current collector at the extreme outer edge of the counter electrodes. It is preferred, but not required, that the current collectors of the counter electrodes be bilaterally symmetrical, so that the electrochemical processes within the bi-cell is balanced.
• a polymer matrix films external to the current collectors are not required for initial bi-cell function or capacity. However, it may be desirable to use such a film to delay or eliminate delamination and prolong battery life.
• the necessity of the polymer matrix film adjacent and external to the current collector will be a function of lamination parameters and designed battery life.
• the specific embodiment of the bi-cell does not rely on either the anode or the cathode being the central electrode.
• the central electrode is anodic
• the counter electrodes will be cathodic.
• the counter electrodes will be anodic.
• a "dry" electrolytic cell precursor is prepared by assembling an anode, a separator membrane, and a cathode, and extracting plasticizer from each of the layers .
• each of the electrodes and the separator can be individually extracted, it is generally more convenient to laminate or assemble the appropriate layers with the plasticizer intact, and extract the plasticizer from the battery precursor as a unit. Methods for battery precursor preparation and extraction are described in U.S. Patent 5,456,000, which is incorporated herein by reference.
• the extracted battery precursor is activated by the addition of a solvent/electrolytic salt solution.
• the electrolyte solvent is a solvent included in the electrolyte solution for the purpose of solubilizing alkali salts during operation of the electrolytic cell.
• the electrolyte solvent can be any compatible, electrochemically stable, relatively non-volatile, aprotic, relatively polar solvent. Preferably these materials have boiling points greater than about 85 °C to simplify manufacture and increase the operation range and shelf life of the battery.
• Typical examples of solvents are dimethyl carbonate (DMC) , diethyl carbonate (DEC) , propylene carbonate (PC) , ethylene carbonate (EC) , methyl ethyl carbonate (MEC) , gamma-butyrolactone, trigly ⁇ ne, tetraglyme, dimethylsulfoxide, dioxolane, sulfolane, and the like, and mixtures of such materials.
• DMC dimethyl carbonate
• DEC diethyl carbonate
• PC propylene carbonate
• EC ethylene carbonate
• MEC methyl ethyl carbonate
• gamma-butyrolactone trigly ⁇ ne
• tetraglyme dimethylsulfoxide
• dioxolane dioxolane
• sulfolane sulfolane
• Electrolyte salts are those inorganic salts which are suitable for use in a non-aqueous electrolyte. Particularly useful are alkali salts wherein the cation of the salt is an alkali selected from the group consisting of lithium, sodium, potassium, rubidium, silver, and cesium, and which are suitable for use in the solvent-containing electrolyte and in the composite electrodes of an electrolyte cell .
• electrolyte salts are known to the art.
• the electrolyte salt typically comprises from about 5 to about 25 weight percent of the inorganic ion salt based on the total weight of the electrolyte.
• the salt is present in the electrolyte solution from about 10 to 20 weight percent. The weight percent of the salt will vary with the type of salt and upon the specific electrolyte solvent employed, as known to the art.
• the laminated battery precursor is generally placed into a moisture-impermeable package, and electrically connected to electrode tabs, prior to activation by the electrolyte solution. Because many electrolyte salts are sensitive to moisture or other chemical compounds, the activation of the electrolytic cell precursor preferably takes place in an inert, moisture-free atmosphere, such as under an argon atmosphere .
• An aluminum grid used for the anode current collector is a sheet of expanded aluminum metal of about 2.5 g/m 2 , available (Exmet, Naugatuck, CT) .
• the surface of the aluminum grid is prepared by etching the grid in a series of solutions. Specifically, the aluminum grid is placed into an acetone bath for 5 minutes. It is then rinsed in water for 1 to 2 minutes. The aluminum grid is then dipped in an etch bath solution comprising 56 grams of potassium hydroxide pellets which have been dissolved in 1 L of methanol. The aluminum grid is removed from the etch solution after 8 minutes, and placed in a fresh water bath for 8 minutes, followed by an acetone bath for 3 minutes .
• An adhesion promoter layer is prepared as a dispersed colloidal solution.
• a grid coating is formed by adding 100 parts (by weight) ethanol, 100 parts Morton Adcote 50C12, and 5 parts SUPER-PTM (M.M.M. Carbon, Willebrock, Belgium) into a ball mix jar, and mixed for one hour.
• the dispersed colloidal solution is diluted in 100 parts ethanol and spray coated onto the etched aluminum grid.
• a cathode structure having a medially placed current collector is prepared.
• a polymer/cathode mixture is prepared by mixing
• DBP dibutyl phthalate
• Two cathode sheets are formed by hot pressing at 130 °C for 30 seconds on an appropriate substrate.
• a current collector of Example 1 is placed on the upper surface of the first cathode sheet .
• a second cathode sheet is then placed on the upper surface of the current collector. Pressure is applied to the resultant three-layer structure, to provide good contact between the layers, and the structure is hot-pressed at 130° C for 15 to 30 seconds to form a cathode structure .
• a cathode structure having a current collector at one edge is prepared.
• Example 2 The procedure of Example 2 is repeated to form two cathode sheets.
• the cathode sheets are layered together, and a current collector of Example 1 is placed on top of the two sheet strata. Pressure is applied to the resultant three-layer structure, to provide good contact between the layers, and the structure is hot- pressed at 130° C for 15 to 30 seconds to form a cathode structure .
• the cathode structure has a double thickness of cathode film with a current collector at one edge.
• a copper grid used for the anode current collector is a sheet of expanded copper metal about 50 ⁇ m thick. It is available under the designation 2Cu5-155 (flattened and annealed) (Delker, Branford, Connecticut) .
• the surface of the copper grid is prepared by etching the grid in a series of solutions. Specifically, the copper grid is placed into an acetone bath for 5 minutes. It is then rinsed in water for 1 to 2 minutes. The copper grid is then dipped in an etch bath solution comprising 1 molar nitric acid (70 ml 70% nitric acid and
• the copper grid is removed from the etch solution after 5 minutes, and placed in a fresh water bath for 8 minutes, followed by an acetone bath for 3 minutes .
• An adhesion promoter layer is prepared as described above, and spray coated onto the etched copper grid.
• An anode structure having a medially placed current collector is prepared.
• a polymer mixture is prepared by placing 12 parts of PVdF:HFP copolymer (KYNARTM Flex 2801) with 60 parts of BG34 (Superior Graphite, Bloomingdale, IL) into a ball mill jar and mixing for 24 hours. This produces a dry, powdery mix in which the particles are well-mixed and of small size.
• DBP dibutyl phthalate
• Anode sheets are formed by hot pressing the anode material at 130 °C for 30 seconds on an appropriate substrate.
• a current collector of Example 3 is placed on the upper surface of a single anode sheet.
• a second anode sheet is used to cover the current collector, and pressure is applied to the resultant structure.
• it is laminated at 120 °C with a hot roll laminator or hot press to form an anode structure.
• Example 6 Improved Anode Structure
• An anode structure having a current collector at one edge is formed.
• Anode sheets are formed by hot pressing anode material at 130 °C for 30 seconds on an appropriate substrate. Two anode sheets are layered together, and a current collector of Example 3 is placed on the upper surface. Pressure is applied to the resultant structure. To provide good contact between the layers, it is laminated at 120 °C with a hot roll laminator or hot press to form an anode structure .
• DBP dibutyl phthalate
• the resultant mixture is hot-pressed at 130 °C for 30 seconds to form a strong, clear film having a thickness of about 2 mil.
• a solid electrochemical cell precursor is formed by laminating a first cathode counter electrode of Example 2 (a control cathode of the prior art) , adjacent a first polymeric separator film of Example 7, and laminating a second cathode counter electrode of Example 3 (a current collector out cathode) , adjacent a second polymeric separator film of Example 7, with the current collector oriented outward.
• the two cathodic counter electrodes are closely matched for weight.
• a central anodic electrode of Example 5 is positioned between the two polymeric separator films of the two counter electrode structures, and the unit is laminated together.
• the layers are positioned as shown in Figure 5 to form a bi-cell precursor 501. Sequentially, they are: the first (control) cathodic counter electrode 514a having a centrally located current collector 515a; a first separator 512a; the central anodic electrode 510; a second separator 512b; and the second (improved) cathodic counter electrode 514b having a current collector 515b at its outermost edge.
• the layers are heated under pressure to form a bi-cell precursor.
• the wt:wt ratio of cathode to anode in the completed bi-cell is 2.5:1.
• the bi-cell is extracted, activated, and packaged as follows:
• the bi-cell precursor is immersed in a bath of methanol or diethyl ether or in a series of methanol or ether baths, to remove the plasticizer.
• the methanol or ether bath(s) provide at least 30 minutes of contact with an excess of methanol or ether.
• the extracted battery precursor is vacuum dried overnight at 40 °C.
• An electrolyte solvent is prepared by combining 267 parts of ethylene carbonate and 133 parts of dimethyl carbonate. To the electrolyte solvent is added 60 parts of LiPF 6 to form an electrolyte solvent solution. The electrolyte solvent solution is added to the bi-cell precursor.
• the activated electrolytic cell is packaged under vacuum in a rigid housing. Positive and negative electrode tabs extend from the packaging. The battery is charged to 4.2V.
• the two cathodic counter electrodes are tabbed separately to allow the current distribution in the individual electrodes to be monitored. Current distribution is assessed during normal constant current cycling of the cell.
• a graph of the competing cathodic counter electrodes during charging of the bi-cell is shown in Figure 6.
• a graph of the competing cathodic counter electrodes during discharge of the bi-cell is shown in Figure 7.
• Data is shown as a function of cell capacity for both charge and discharge.
• the cells are cycled at a current density of 0.5mA/cm 2 (i.e., 24 mA total) between 3 and 4.2 V at 23°C.
• the improved (current collector out) cathode performs more efficiently, that is, it draws proportionately more current in competition with the current collector medial cathode.
• a solid electrochemical cell precursor is formed by laminating a first anodic counter electrode of Example 5 (a control anode of the prior art) , adjacent a first polymeric separator film of Example 7, and laminating a second anodic counter electrode of Example 6 (a current collector out anode) , adjacent a second polymeric separator film of Example 7, with the current collector oriented outward.
• the two anodic counter electrodes are closely matched for weight .
• a central cathodic electrode of Example 2 is positioned between the two polymeric separator films of the two counter electrode structures, and the unit is laminated together.
• the layers are positioned as shown in Figure 5 to form a bi-cell precursor 501. Sequentially, they are: the first (control) anodic counter electrode 514a having a centrally located current collector 515a; a first separator 512a; the central cathodic electrode 510; a second separator 512b; and the second (improved) anodic counter electrode 514b having a current collector 515b at its outermost edge.
• the layers are heated under pressure to form a bi-cell precursor.
• the wt:wt ratio of cathode to anode in the completed bi-cell is 2.5:1.
• the bi-cell is extracted, activated, and packaged as described above in Example 8.
• the two anodic counter electrodes are tabbed separately to allow the current distribution in the individual electrodes to be monitored. Current distribution is assessed during normal constant current cycling of the cell.
• a graph of the competing anodic counter electrodes during charging of the bi-cell is shown in Figure 8.
• Data is shown as a function of cell capacity for both charge and discharge.
• the cells are cycled at a current density of 0.5mA/cm 2 (i.e., 24 mA total) between 3 and 4.2 V at 23°C.
• anode performs more efficiently, that is, it draws proportionately more current in competition with the current collector medial anode.
• the improved anode apparently pulls more current (and thus ultimately attains a higher level of lithium ion concentration when the cell is fully charged) .
• the improved anodic counter electrode again appears more efficient, although this may simply reflect the higher initial specific capacity in this anodic counter electrode attained during the charging process .
• a solid electrochemical cell precursor is formed as described in Example 8, substituting for the second counter electrode a cathodic counter electrode having a current collector at the outermost edge of the cathodic material, and a polymer matrix film next to the current collector.
• the layers are heated under pressure to form a bi-cell precursor.
• the bi-cell is extracted, activated, and packaged as described in Example 8.
• the two cathodic counter electrodes are tabbed separately to allow the current distribution in the individual electrodes to be monitored. Current distribution is assessed during normal constant current cycling of the cell.
• the cells are cycled at a current density of 0.5mA/cm 2 (i.e., 24 mA total) between 3 and 4.2 V at 23°C.
• the improved cathode comprising cathodic material-current collector- polymer matrix film performs more efficiently than the current collector medial cathode.
• a solid electrochemical cell precursor is formed as described in Example 8, substituting for the second counter electrode a cathodic counter electrode having a current collector at the innermost edge of the cathodic material.
• the layers are heated under pressure to form a bi-cell precursor.
• the bi-cell is extracted, activated, and packaged as described in Example 8.
• the two cathodic counter electrodes are tabbed separately to allow the current distribution in the individual electrodes to be monitored. Current distribution is assessed during normal constant current cycling of the cell.
• the cells are cycled at a current density of 0.5mA/cm 2 (i.e., 24 mA total) between 3 and 4.2 V at 23°C.
• a solid electrochemical cell precursor is formed as described in Example 10, substituting for the second counter electrode an anodic counter electrode having a current collector at the outermost edge of the anodic material, and a polymer matrix film next to the current collector.
• the layers are heated under pressure to form a bi-cell precursor.
• the bi-cell is extracted, activated, and packaged as described in Example 10.
• the two anodic counter electrodes are tabbed separately to allow the current distribution in the individual electrodes to be monitored. Current distribution is assessed during normal constant current cycling of the cell as described in Example 11. During both charge and discharge the improved (current collector out) anode performs more efficiently than the current collector medial anode.
• a solid electrochemical cell precursor is formed as described in Example 10, substituting for the second counter electrode an anodic counter electrode having a current collector at the innermost edge of the anodic material .
• the layers are heated under pressure to form a bi-cell precursor.
• the bi-cell is extracted, activated, and packaged as described in Example 10.
• the two anodic counter electrodes are tabbed separately and tested as described in Example 11. During both charge and discharge the current-collector-central anode performs somewhat less efficiently than the current collector medial anode.
• Figure 3 pertains to a preferred "anode-out" bi-cell. This arrangement is preferred over “cathode-out” .
• the cathode-out arrangement is exemplified by Figure 2 where counter electrodes 214a and 214b are positive electrodes (cathodes) and the central electrode 210 is the negative electrode (anode) .
• the preferred anode-out arrangement is illustrated and further understood by reference back to Figure 2 where the opposite arrangement of electrodes is made.
• the electrodes 214a and 214b are anode electrodes and the central electrode 210 is the cathode electrode.
• the anode-out design was tested and compared to a cathode-out design.
• the anode-out battery provided a 2% to 5% increase in cell capacity. Additionally, battery cycle life (1 cycle is discharge to 3 volts, then a charge to 4.2 volts) in the anode-out design was improved, showing up to 600 cycles at 80% residual capacity, and up to 1200 cycles at 60% residual capacity.
• the comparative bi-cell consisted of the first cathode, a separator, an anode, a second separator and second cathode.
• the improved anode-out arrangement consisted of layers sequentially being first an anode, then a separator, a cathode, a second separator, and the second anode.
• a cathode current collector, anode current collector and separator were conventionally made as described with respect to Examples 1, 4 and 7 above, respectively, and the cathode structures were prepared by the method of Example 2 and the anode by the method of Example

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