COMPONENT FOR USE IN AN ENERGY STORAGE DEVICE OR AN ENERGY CONVERSION DEVICE AND METHOD FOR THE MANUFACTURE THEREOF

Abstract

A component for use in an energy storage device or an energy conversion device comprises a first part and a second part, wherein the first part comprises particles of a ceramic material, and the second part is provided by a sheet having a plurality of through-thickness apertures. The second part is at least partially embedded in the first part.

Claims

1. A component for use in an energy storage device or an energy conversion device, the component comprising a first part and a second part, wherein the first part comprises particles of a ceramic material, and the second part is provided by a sheet having a plurality of through-thickness apertures; wherein the second part is at least partially embedded in the first part.

2. The component according to claim 1, wherein the ceramic material is selected from the group consisting of: electrode active materials; electrolytes; piezoelectric materials; photovoltaic materials; and thermoelectric materials.

3. The component according to claim 1, wherein the second part is provided by a sheet of electronically conductive material.

4. The component according to claim 3, wherein the second part comprises a metal or a metal alloy.

5. The component according to claim 4, wherein the metal or metal alloy comprises one or more elements selected from the group consisting of: iron, nickel, copper, aluminium, titanium, and platinum.

6. The component according to claim 1, wherein the through-thickness apertures are arranged in a grid.

7. The component according to claim 6, wherein the second part is provided by a woven mesh.

8. The component according to claim 7, wherein the woven mesh has 5-500 strands per cm, when measured in a direction perpendicular to the strands.

9. The component according to claim 8, wherein the woven mesh has 30-250 strands per cm, when measured in a direction perpendicular to the strands.

10. The component according to claim 9, wherein the woven mesh has 30-100 strands per cm, when measured in a direction perpendicular to the strands.

11. The component according to any claim 1, wherein the apertures have a width in the range 10-1000 ?m.

12. The component according to claim 11, wherein the apertures have a width in the range 10-200 ?m.

13. The component according to claim 12, wherein the apertures have a width in the range 50-200 ?m.

14. The component according to claim 1, wherein the component is an electrode for a battery cell, particularly a solid state battery cell, and the ceramic material is an electrode active material.

15. The component according to claim 14, wherein the particles of electrode active material comprise at least one electrode active material selected from the group consisting of: lithium nickel cobalt aluminium oxide (LiNixCoyAlzO2, wherein x>0; y>0; z>0 and x+y+z=1); lithium cobalt oxide (LiCoO2); lithium iron phosphate (LiFePO4); lithium manganese nickel oxide (LiMn1.5Ni0.5O4); lithium cobalt phosphate (LiCoPO4); lithium nickel cobalt manganese oxide (LiNixCoyMnzO2, wherein x>0; y>0; z>0 and x+y+z=1); vanadium oxide (V2O5); LiVOPO4; Li3V2(PO4)3; LiMPO4 (wherein M=Ni, Mn); tin oxide and lithium titanate oxide (Li4Ti5O12 or Li2TiO3).

16. The component according to claim 14, wherein the first part further comprises an ionically-conductive constituent that is distributed between the particles of electrode active material.

17. The component according to claim 14, wherein the amount of any electronically-conductive constituent in the first part of the electrode is less than 10 vol % relative to the total volume of the electrode active material.

18. A method of making the component according to claim 1, comprising the steps of: providing a sheet having a plurality of through-thickness apertures; combining particles of a ceramic material with a liquid phase to form a slurry; depositing the slurry onto the sheet having the plurality of through-thickness apertures; after deposition of the slurry onto the sheet, wetting the particles of the ceramic material with a solvent that is configured to partially solubilise the ceramic material; and sintering the wetted particles of the ceramic material by applying pressure and heat to the particles to evaporate the solvent and densify the ceramic material, wherein the sintering temperature is no more than 200? C. above the boiling point of the solvent.

19. The method according to claim 18, wherein the step of wetting the particles of the ceramic material with a solvent comprises applying the solvent to the particles by means of a spraying process.

20. The method according to claim 18, wherein the step of wetting the particles of the ceramic material with a solvent comprises applying the solvent to the particles in the form of a vapour of the solvent.

21. The method according to claim 18, wherein the liquid phase comprises a polymeric binder phase and the method further comprises the step, after the step of depositing the slurry onto the sheet and before the step of wetting the particles of the ceramic material with the solvent, of heating the slurry to reduce the concentration of the polymeric binder phase in the slurry.

22. A method of making the component according to claim 1, comprising the steps of: providing a sheet having a plurality of through-thickness apertures; combining particles of a ceramic material with a solvent to form a slurry, the solvent being configured to solubilise the ceramic material; depositing the slurry onto the sheet having the plurality of through-thickness apertures; sintering the particles of the ceramic material by applying pressure and heat to the slurry to evaporate the solvent and densify the ceramic material, wherein the sintering temperature is no more than 200? C. above the boiling point of the solvent.

23. The method according to claim 22, wherein the slurry further comprises a polymeric binder and the method further comprises the step, after the step of sintering the slurry to densify the ceramic material, of heating the densified material to a temperature above the sintering temperature, to reduce the concentration of the polymeric binder phase in the densified material.

24. The method according to claim 18, wherein the sintering temperature is 300? C. or less.

25. The method according to claim 18, wherein the applied pressure is 300 MPa or less.

26. The method according to claim 18, wherein the step of sintering the particles of the ceramic material by applying pressure and heat to evaporate the solvent and densify the ceramic material takes 60 minutes or less.

27. The method according to any claim 18, wherein the particles of the ceramic material have a d50 size in the range 10 nm to 50 ?m.

28. The method according to claim 18, wherein the slurry is deposited onto the sheet having the plurality of through-thickness apertures through a mask.

29. The method according to claim 18, wherein the slurry is deposited onto the sheet having the plurality of through-thickness apertures by means of a tape-casting or screen-printing process.

30. The method according to claim 18, wherein the solvent is selected from the group consisting of: water, acetic acid, polycarbonate, dimethylformamide and benzyl alcohol.

31. The method according to claim 18, wherein the component is an electrode for a battery cell, particularly a solid state battery cell, and the ceramic material is an electrode active material.

32. The method according to claim 31, wherein the slurry further comprises particles of an ion-conductive material.

33. The method according to claim 31, wherein the amount of any solid electronically-conductive constituent in the slurry is less than 10 vol % relative to the total volume of the particles of electrode active material.

34. A component for use in an energy storage device or an energy conversion device, the component being obtained or obtainable through the method according to claim 18.

35. An energy storage device or energy conversion device comprising a component according to claim 1.

36. The energy storage device or energy conversion device according to claim 35, wherein the device is selected from the group consisting of: batteries (including solid state batteries), capacitors, fuel cells (including solid oxide fuel cells and polymer electrolyte fuel cells), photovoltaic devices, piezoelectric devices, and thermoelectric converters.

37. A solid state battery cell comprising a component according to claim 1, wherein the component is an electrode, the battery cell further comprising an electrolyte layer disposed on a face of the electrode.

Description

DETAILED DESCRIPTION

[0101] The invention will now be described by way of example with reference to the following Figures in which:

[0102] FIGS. 1a-f show scanning electron micrographs of cross sectional views of Examples 1, 2, 3, 8, 4, and 5 respectively;

[0103] FIG. 2 is a graph of normalised capacity against cycle number for a battery cell including the cathode of Example 3;

[0104] FIG. 3 is a graph of voltage against time for a battery cell including the cathode of Example 3;

[0105] FIG. 4 is a graph of mesh weight per unit area against mesh size.

Cathode Preparation

[0106] Slurries were prepared from the constituents set out in Table 1. First, the binder and the electrolytic salt were dissolved in the solvent and then the solvent was mixed with the remaining constituents. The mixing process was carried out in a planetary ball mixer, initially for 10 minutes at 1000 rpm, followed by 5 minutes at 800 rpm.

TABLE-US-00001 TABLE 1 Amount Constituent Function (wt %) NMC (LiNi.sub.0.33Mn.sub.0.33Co.sub.0.33O.sub.2): Particles of cathode 38 grade A or grade B active material LAGP (Li.sub.1.5Al.sub.0.5Ge.sub.1.5(PO.sub.4).sub.3) Particles of ionically- 8 conductive material LITFSI Electrolytic salt 3 Carbon nanotubes Electronically- 1 conductive material Propylene carbonate Solvent for the binder 47.5 phase and electrolytic salt Poly(propylene carbonate) Binder phase 2.5

[0107] Two NMC grades were used, and their properties are set out in Table 2. The particle size analysis was carried out using laser diffraction of a liquid dispersion of the particles, following ISO 13320:2020.

TABLE-US-00002 TABLE 2 Particle size (?m) Grade D10 D50 D90 A 7.2 12.4 22.1 B 6.8 12.7 23.9

[0108] Examples 1-12 were prepared by screen-printing the slurry onto a woven metal mesh through a mask having a thickness of 500 ?m and an opening of 30-35 mm diameter. Comparative Examples 1-4 were prepared by screen-printing the slurry onto a metal foil through a mask having a thickness of 500 ?m and an opening of 30-35 mm diameter.

[0109] Next, the mask was removed and the samples were heated to 250? C. at a rate of 0.5? C./minute and held at this temperature for 6 minutes to remove the organic binder phase.

[0110] Next, water was sprayed onto the surface of the screen-printed samples, in order to wet the particles of the electrode active material and partially solubilise them.

[0111] The samples were then placed in a heated uniaxial press and held at 130? C. for 10 minutes at a pressure of 30.59 MPa to sinter them.

[0112] Once the sintering step was complete, the samples were removed from the press and examined to assess the quality of the adhesion of the sintered material to the mesh or foil substrate. The quality of the adhesion was defined according to the following categories: [0113] Poor adhesion: the sintered material did not adhere to the substrate at all; [0114] Fair adhesion: the sintered material initially adhered to the substrate, but easily became detached, for example, when an attempt was made to cut the sample through its thickness; [0115] Good adhesion: the sintered material adhered to the substrate, even when an attempt was made to cut the sample.

TABLE-US-00003 TABLE 3 Mesh Aperture Mesh NMC Example size Strands/cm size (?m) material grade Performance 1 18 7.1 960 Stainless A Good adhesion steel 2 30 11.8 570 Stainless A Good adhesion steel 3 60 23.6 260 Stainless A Good adhesion steel 4 200 78.7 70 Stainless A Fair adhesion steel 5 500 196.9 26 Stainless A Fair adhesion steel 6 60 23.6 250 Nickel A Good adhesion 7 60 23.6 260 Copper A Good adhesion 8 120 47.2 120 Aluminium B Good adhesion 9 30 11.8 570 Stainless B Good adhesion steel 10 60 23.6 260 Stainless B Good adhesion steel 11 200 78.7 70 Stainless B Good adhesion steel 12 500 196.9 26 Stainless B Good adhesion steel

TABLE-US-00004 TABLE 4 Comparative Substrate Thick- Surface NMC Perfor- Example material ness treatment grade mance 1 Stainless 50 ?m Roughened A Poor steel foil using adhesion sandpaper 2 Stainless 100 ?m Roughened A Poor steel foil using adhesion sandpaper 3 Aluminium No foil adhesion

[0116] Cross sectional views of Examples 1, 2, 3, 8, 4, and 5 are shown in FIGS. 1a-f respectively.

Battery cell A battery cell was prepared using the electrode of Example 3, an LAGP/polymer electrolyte, a lithium anode and a copper current collector. After forming the battery, electrochemical testing was performed using the following procedure: [0117] Charge=constant current to a voltage of 4.2 V, followed by maintaining the battery at this voltage for 60 minutes [0118] Discharge=constant current to a voltage of 2.7 V.

[0119] The results are shown in FIGS. 2 and 3, which shows that cycling was successfully achieved, with high efficiency after forming stage.

Mesh Weight

[0120] FIG. 4 is a graph of mesh weight per unit area against mesh size for stainless steel, aluminium and nickel meshes, and additionally includes a band showing the weight per unit area of typical 50 ?m thick stainless steel foils. From this, is can be seen that fine meshes (e.g. aluminium mesh having a mesh size of 120, as well as stainless steel meshes having mesh sizes of 200 and 500) have a lower weight per unit area than 50 ?m thick stainless steel foils. This may assist in increasing the energy density per unit weight of a battery containing an electrode according to the present invention.