COMPOSITE CATHODE MATERIAL

Abstract

A composite cathode material includes a gel polymer electrolyte and particles of a cathode material. The particles of the cathode material are arranged in the gel polymer electrolyte.

Claims

1. A composite cathode material comprising a gel polymer electrolyte and particles of a cathode material, the particles of the cathode material being arranged in the gel polymer electrolyte.

2. The composite cathode material according to claim 1, wherein the particles of the cathode material are comprised in the composite cathode material in an amount of at least 50 wt % of the composite cathode material, on a dry weight basis.

3. The composite cathode material according to claim 1, wherein the particles of the cathode material are arranged in the gel polymer electrolyte such that they are substantially homogenously dispersed throughout the gel polymer electrolyte.

4. The composite cathode material according to claim 1, wherein the gel polymer electrolyte is obtainable from a UV-crosslinkable gel polymer electrolyte precursor.

5. The composite cathode material according to claim 1, wherein the gel polymer electrolyte comprises polyethylene oxide (PEO), polypropylene oxide (PPO), polymethylmethacrylate (PMMA) polyacrylonitrile (PAN), polyvinylidene difluoride (PVDF), a combination thereof, or one or more copolymers obtainable therefrom.

6. The composite cathode material according to claim 1, wherein the gel polymer electrolyte comprises LiClO.sub.4, LiBF.sub.4, LIPF.sub.6, LiAsF.sub.6, LiCF.sub.3SO.sub.3, LiN(CF.sub.3SO.sub.2).sub.2 (LiTFSI), or a combination thereof.

7. The composite cathode material according to claim 1, wherein the gel polymer electrolyte comprises polyethylene glycol (PEG), polyethylene glycol dimethyl ether (PEGDME), dibutyl phthalate (DBP), dimethyl phthalate (DMP), dioctyl phthalate (DOP), succinonitrile (SN), ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), -butyrolactone (-BL), or a combination thereof.

8. The composite cathode material according to claim 1, wherein the particles of the cathode material comprise lithium cobalt oxide (LiCoO.sub.2), lithium manganese oxide (LiMn.sub.2O.sub.4), lithium nickel manganese cobalt oxide (LiNiMnCoO.sub.2), lithium iron phosphate (LiFePO.sub.4), lithium nickel cobalt aluminium oxide (LiNiCoAlO.sub.2), lithium titanate (Li.sub.2TiO.sub.3), or a combination thereof.

9. The composite cathode material according to claim 1, wherein the particles of the cathode material have an average particle size of less than 0.1 m.

10. The composite cathode material according to claim 1, wherein the composite cathode material is porous.

11. A method of manufacturing a composite cathode material comprising: mixing particles of a cathode material with a gel polymer electrolyte precursor to provide a mixture; and cross-linking the gel polymer electrolyte precursor of the mixture to provide the composite cathode material.

12. The method according to claim 11, wherein the mixture is cast to form a sheet of mixture before cross-linking the gel polymer electrolyte precursor.

13. The method according to claim 11, wherein the mixture is supplied to a mold before cross-linking the gel polymer electrolyte precursor.

14. The method according to claim 11, wherein the mixture is supplied to a surface of a current collector before cross-linking the gel polymer electrolyte precursor.

15. The method according to claim 11, wherein the cross-linking comprises supplying the gel polymer electrolyte precursor with UV radiation.

16. The method according to claim 11, wherein after the cross-linking, the composite cathode material is wound into a bobbin.

17. A laminate electrochemical cell comprising: an anode layer; and a composite cathode layer comprising the composite cathode material of claim 1.

18. The laminate electrochemical cell according to claim 17, further comprising a gel polymer electrolyte layer arranged between the anode layer and the composite cathode layer.

19. The laminate electrochemical cell according to claim 17, further comprising a ceramic layer arranged between the anode layer and the composite cathode layer.

20. The laminate electrochemical cell according to claim 19, wherein the ceramic layer comprises lithium phosphorous oxy-nitride (LiPON).

21. The laminate electrochemical cell according to claim 17, wherein the anode layer comprises silicon, carbon (optionally as graphite, graphene, activated carbon and/or carbon black), indium tin oxide (ITO), molybdenum dioxide (MoO.sub.2), lithium titanate (Li.sub.2TiO.sub.3), lithium alloy, metallic lithium, copper, or combinations thereof.

22. A method of manufacturing a laminate electrochemical cell, the method comprising: providing a layer of composite cathode material comprising a gel polymer electrolyte and particles of a cathode material, the particles of the cathode material being arranged in the gel polymer electrolyte; providing an anode layer; and combining the layer of composite cathode material and the anode layer to provide the laminate electrochemical cell.

23. The method according to claim 22, wherein the providing the layer of composite cathode material comprises: supplying a mixture of gel polymer electrolyte precursor and particles of a cathode material to a surface of a first current collector; and cross-linking the gel polymer electrolyte precursor of the mixture to provide the layer of composite cathode material.

24. The method according to claim 22, further comprising providing a gel polymer electrolyte layer on a surface of the layer of composite cathode material, wherein the combining the layer of composite cathode material and the anode layer comprises arranging the gel polymer electrolyte layer between the layer of composite cathode material and the anode layer.

25. The method according to claim 22, further comprising providing a ceramic layer on a surface of the anode layer, wherein the combining the layer of composite cathode material and the anode layer comprises arranging the ceramic layer between the layer of composite cathode material and the anode layer.

26. A battery stack comprising a plurality of laminate electrochemical cells, each cell comprising: a first current collector; a composite cathode layer arranged on a surface of the first current collector, the composite cathode layer comprising a gel polymer electrolyte and particles of a cathode material, the particles of the cathode material being arranged in the gel polymer electrolyte; a second current collector; and an anode layer arranged on a surface of the second current collector.

27. The battery stack according to claim 26, wherein the plurality of electrochemical cells comprises a first electrochemical cell and a second electrochemical cell, configured such that the first current collector of the first cell is also the first current collector of the second cell.

28. An electrically-powered device comprising the laminate electrochemical cell according to claim 17.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0100] FIG. 1 is a schematic diagram of a cross-section of a composite cathode material according to examples.

[0101] FIG. 2 is a schematic diagram of a cross-section of a battery stack according to examples.

[0102] FIG. 3 is a flow chart of a method according to examples.

[0103] FIG. 4 is a schematic flow diagram of a method according to examples, depicting cross-sections of an electrochemical cell and component portions of the electrochemical cell at points in the method.

[0104] FIG. 5 is a schematic flow diagram of a method according to examples, depicting cross-sections of an electrochemical cell and component portions of the electrochemical cell at points in the method.

[0105] FIG. 6 is a schematic flow diagram of a method according to an example, depicting cross-sections of an electrochemical cell and component portions of the electrochemical cell at points in the method.

DETAILED DESCRIPTION

[0106] FIG. 1 shows a cross-section of one example of a composite cathode material 1 according to examples. The composite cathode material 1 comprises a gel polymer electrolyte 2 and particles of a cathode material 3 arranged in the gel polymer electrolyte 2. The particles of cathode material 3 are dispersed throughout the gel polymer electrolyte 2. The particles 3 are granular in form; the composite cathode material 1 is obtained from mixing gel polymer electrolyte precursor and powdered cathode material, and crosslinking the precursor to provide the composite cathode material 1.

[0107] FIG. 2 shows a cross-section of one example of an electrochemical cell 10 according to examples. The cell 10 comprises a composite cathode layer 11, an anode 12, a ceramic layer 13, and a gel polymer electrolyte layer 14. The cell 10 typically comprises current collectors 15, 16.

[0108] The ceramic layer 13 juxtaposes the anode 12 as a LiPON coating. The ceramic layer 13 contacts a first surface 12a of the anode layer.

[0109] The gel polymer electrolyte layer 14 juxtaposes the ceramic layer 13. The polymer electrolyte layer 14 and the ceramic layer 13 are different, discrete layers having different compositions.

[0110] The composite cathode layer 11 juxtaposes the gel polymer electrolyte layer 14. The gel polymer electrolyte layer contacts a first surface 11a of the composite cathode layer 11.

[0111] The composite cathode layer 11 of the cell 10 comprises the composite cathode material 1 depicted in FIG. 1. The anode layer 12 of the cell 10 comprises materials typically employed in conventional Li-ion electrochemical cells.

[0112] The first current collector 15 is arranged on a second surface 11b of the composite cathode 11, the second surface 11b being opposite to the interface between the composite cathode 11 and the gel polymer electrolyte layer 14 at the first surface 11a of the composite cathode 11. The second current collector 16 is arranged on a second surface 12b of the anode 12, the second surface 12b being opposite to the interface between the anode 12 and the ceramic layer 13 at the first surface 12a of the anode 12. The current collectors 15, 16 comprise a metal layer.

[0113] FIG. 3 shows a cross-section of one example of a battery stack 100 comprising a plurality of electrochemical cells 10, 20, 30, 40. As shown in FIG. 3, the plurality comprises a first cell 10, a second cell 20, a third cell 30, and a fourth cell 40. Other examples of battery stack 100 need only in fact comprise at least two electrochemical cells; and, the number of cells shown in FIG. 3 is purely exemplary. The description and teaching regarding FIG. 3 is also explicitly disclosed in relation to any battery stack comprising any number of electrochemical cells according to the present disclosure, to the extent that said teaching and said battery stack are technically compatible.

[0114] Each cell 10, 20, 30, 40 corresponds to the cell 10 shown in FIG. 2. The components of each cell 10, 20, 30, 40 are labelled such that the second digit corresponds to that used in FIG. 2 to indicate where components are equivalent, and the first digit corresponds to the first digit of the cell of which it is comprised.

[0115] The battery stack 100 is a back-to-back stack, in which every other cell in the stack is reversed so that each current collector has either an anode on each opposing face or a cathode on each opposing face. In particular, in FIG. 3, the composite cathode 11 of the first cell 10 and the composite cathode 21 of the second cell 20 are arranged on opposite faces of a current collector 15/25. The current collector 15/25 comprises an outer metal foil surface and a core having lower electrical conductivity than the outer metal foil surface, and thus is configured to form an electrode on both faces of the layer, e.g. the first current collector 15 of the first cell 10 and the first current collector 25 of the second cell 20. Thus, the first current collector 15 of the first cell 10 is the first current collector 25 of the second cell. The same applies to the first current collector 35 of the third cell 30 and the first current collector 45 of the fourth cell 40 mutatis mutandis.

[0116] The anode 22 of the second cell 20 and the anode 32 of the third cell 30 are arranged on opposite faces of a current collector 26/36. The current collector 26/36 comprises an outer metal foil surface and a core having lower electrical conductivity than the outer metal foil surface, and thus is configured to form an electrode on both faces of the layer, e.g. the second current collector 26 of the second cell 20 and the second current collector 36 of the third cell 30. Although not shown in FIG. 2, the same applies to the anode 12 and the second current collector 16 of the first cell 10 mutatis mutandis, and to the anode 42 and the second current collector 46 of the fourth cell mutatis mutandis, if further electrochemical cells are comprised in the battery stack 200.

[0117] The composite cathode 11, 21, 31, 41 of each cell 10, 20, 30, 40 comprises the composite cathode material 1 depicted in FIG. 1. Taken together, the composite cathodes 11, 21, the gel polymer electrolyte layers 14, 24 and first current collector 15, 25, form an electrode 110. In the same way, taken together, the composite cathodes 31, 41, the gel polymer electrolyte layers 34, 44 and the first current collector 35, 45 form an electrode 120.

[0118] The anodes 12, 22, 32, 42 comprise material typically employed in conventional Li-ion electrochemical cells. Taken together, the anodes 22, 32, the ceramic layers 23, 33 and the second current collector 26, 36 of the second and third cells 20, 30 form an electrode 130.

[0119] FIG. 4 depicts a particular example of the electrode 130 shown in FIG. 3. The second current collector 26, 36 comprises a polymer substrate 50 and a layer of copper metal 52, 54 provided on each opposing face of the polymer substrate 50. Each layer of copper metal 52, 54 typically has a thickness of approximately 2 m, and the polymer substrate 50 has a thickness of approximately 2 m. A layer of lithium metal is provided as an anode layer 22, 32 on each opposing face of the current collector 26, 36. Each lithium anode layer 22, 32 has a thickness of approximately 1 m. A ceramic layer 23, 33 comprising LiPON is encapsulates each lithium metal anode 22, 32. Each layer of LiPON 23, 33 has a thickness of approximately 1 m. This method provides a double-sided protected lithium metal anode on a current collector with an overall thickness of approximately 10 m.

[0120] FIG. 5 is a flow chart depicting a method 200 of manufacturing a composite cathode material according to examples.

[0121] The method 200 comprises mixing 210 particles of a cathode material with a gel polymer electrolyte precursor to provide a mixture. Mixing 210 the components of the mixture comprises any suitable process as described herein.

[0122] The method 200 further comprises crosslinking 220 the gel polymer electrolyte precursor of the mixture to provide the composite cathode material. Crosslinking 220 the gel polymer electrolyte comprises any suitable process as described herein.

[0123] FIG. 6 is a flow chart depicting a method 300 of manufacturing an electrochemical cell according to examples. The method 300 comprises providing 310 a layer of composite cathode material comprising a gel polymer electrolyte and particles of a cathode material, the particles of the cathode material being arranged in the gel polymer electrolyte. Providing 310 the composite cathode layer comprises any suitable process as described herein.

[0124] The method 300 comprises providing 320 an anode layer. Providing 320 the anode layer comprises any suitable process described herein.

[0125] The method 300 comprises combining 330 the composite cathode layer and the anode layer provide the laminate battery cell. In examples (not shown), these items are combined such that further layers such as a gel polymer electrolyte layer and/or a ceramic layer are arranged between the composite cathode layer and the anode layer. The combining 330 comprises any suitable process described herein.

[0126] In examples (not shown in FIG. 6, but shown in FIG. 7), before the combining 330, the method 300 comprises providing 340 a gel polymer electrolyte layer on a surface of the composite cathode layer. The providing 340 a gel polymer electrolyte layer comprises any suitable process described herein.

[0127] In examples (not shown in FIG. 6, but shown in FIG. 7), before the combining 330, the method 300 comprises providing 350 a ceramic layer on a surface of the anode layer. The providing 350 a ceramic layer comprises any suitable process described herein.

[0128] FIG. 7 is a flow diagram illustrating schematically a method 400 according to an example of the method 300 depicted in FIG. 6 (a first example, and a second example). FIG. 7 shows cross-sections of an electrochemical cell 10 and component portions of the electrochemical cell 10 at points in the method 400. Where aspects of FIG. 7 correspond to features or method blocks depicted in previously-described figures, the same reference numbers are employed to aid understanding only. For the avoidance of doubt, limitations or requirements described in respect of the previously-described figures do not apply to the method 400 depicted in FIG. 7, and vice versa.

[0129] The method 400 comprises providing 310 a composite cathode layer 11. The composite cathode layer 11 is provided on a current collector 15 as a current collector-composite cathode laminate 410 (a composite cathode laminate). The composite cathode layer 11 is provided 310 by mixing particles of a cathode material with a gel polymer electrolyte precursor, supplying the mixture to a surface of the current collector 15, and cross-linking the gel polymer electrolyte precursor of the mixture to provide the composite cathode layer 11 on the current collector 15.

[0130] The method 400 further comprises providing 340 a gel polymer electrolyte layer 14 on the composite cathode layer 11. The gel polymer electrolyte layer 14 is provided by casting a mixture of lithium salt, polymer, and solvent onto a surface of the cathode layer 11 and crosslinking the mixture to provide the gel polymer electrolyte layer 14. Together, the current collector 15, cathode 11 and gel polymer electrolyte layer 14 form a composite cathode-electrolyte laminate 420.

[0131] The method 400 further comprises providing 320 an anode layer 12. Providing 320 the anode layer 12 comprises depositing lithium metal on a current collector 16 to provide a lithium metal film via thermal deposition. The anode layer 12 and current collector 16 together form an anode laminate 430.

[0132] The method 400 further comprises providing 350 a ceramic layer 13. Providing 350 the ceramic layer 13 comprises depositing ceramic material via vacuum deposition such as PVD or CVD. Together, the current collector 16, anode 12 and ceramic layer 13 form an anode-ceramic laminate 440.

[0133] The method 400 comprises combining 340 the layers to form an electrochemical cell 10. In the example depicted, the combining 340 comprises aligning the anode-ceramic laminate 440 with the composite cathode-electrolyte laminate 420, and hot rolling or pressing the laminates 340 to provide the cell 10.

[0134] FIG. 7 depicts an example of the combining 340 step of the method 400 shown in FIG. 7. In this example, the combining 340 is a roll-to-roll manufacturing method. The cathode-electrolyte laminate 420 has been wound into a first bobbin or roll 510, and the anode-ceramic laminate 440 has been wound into a second bobbin or roll 520. The first 510 and second 520 rolls are fed into a roller apparatus and pressed together to provide the cell 10.

[0135] The above examples are illustrative. Further examples are envisaged. It is to be understood that any feature described in relation to any one example may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the examples, or any combination of any other of the examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the accompanying claims.