Anode fabrication by pattern lamination, anodes made thereby, and electrochemical devices incorporating such anodes
A method of forming anodes for electrochemical devices by laminating a metal foil to a current collector and creating anode-active-material patches, composed of the metal foil, that are spaced from one another by inter-patch regions, wherein each inter-patch region provides a location for forming one or more electrical tabs of the finished anodes. The method can further include applying conductive-coating patches to the current collector prior to laminating the metal foil to the current collector, wherein each conductive-coating patch corresponds to one of the anode-active-material patches. In some embodiments, the conductive-coating patches can assist with forming the anode-active-material patches and/or can improve the cycling performance of an electrochemical device made using anodes made therewith. Anodes containing anode-active material and conductive coatings applied to current collectors are also disclosed.
1. A method of forming anodes for one or more electrochemical devices, wherein each of the anodes has an electrical tab, the method comprising:
providing a current-collector web;
laminating, on a first side of the current-collector web, a metal foil to the current-collector web as multiple anode-active-material patches spaced from one another so as to provide a webbed anode precursor that includes the anode-active-material patches and inter-patch regions not containing the metal foil;
forming the anodes from the webbed anode precursor so that each anode is formed from a respective anode region of a corresponding anode-active-material patch and the electrical tab corresponding to the each anode is formed from one of the inter-patch regions, wherein forming the anodes includes separating each anodes from the webbed anode precursor; and
prior to laminating the metal foil to the current-collector web, applying an electrically conductive coating at each locating where the metal foil will be secured to the current-collector web and not applying the electrically conductive coating at each inter-patch region so as to form an electrically-conductive-coating patch corresponding to a respective one of the anode-active-material patches.
2. The method of claim 1 , wherein the electrically conductive coating comprises electrically conductive particles and a binder.
3. The method of claim 2 , wherein the electrically conductive particles comprise electrically conductive carbon particles.
4. The method of claim 3 , wherein the binder is selected from the group consisting of poly vinylidene fluoride, poly vinylidene fluoride-hexafluoropropylene, carboxymethyl cellulose, styrene-butadiene rubber, and any mixture thereof.
5. The method of claim 1 , wherein the electrically conductive coating consist essentially of a binder and conductive-carbon particles in an amount of about 70 wt. % to about 90 wt. % of the electrically conductive coating.
6. The method of claim 1 , wherein applying the electrically conductive coating includes applying the electrically conductive coating so as to have a cured thickness of about 0.1 μm to about 5 μm.
7. The method of claim 1 , wherein applying the electrically conductive coating includes applying the electrically conductive coating so as to have a cured thickness of about 0.5 μm to about 2 μm.
8. The method of claim 1 , wherein applying the electrically conductive coating includes applying the electrically conductive coating so as to have a cured thickness of about 1 μm.
9. The method of claim 1 , wherein the metal foil is provided in sheets, and the method further comprises using the conductive-coating patches to align the sheets of the metal foil with the conductive-coating patches in conjunction with the laminating of the metal foil to the current-collector web.
10. The method of claim 9 , wherein using the conductive-coating patches to align the sheets of the metal foil with the conductive-coating patches includes using an optical detector to detect an edge of each of the conductive-coating patches.
11. The method of claim 1 , wherein each conductive-coating patch has a size and a shape and the corresponding anode-active-material patch is in registration with a respective one of the conductive-coating patches and has a size and a shape substantially the same as the size and the shape of the respective one of the conductive-coating patches.
12. The method of claim 1 , wherein the current-collector web has a width and a length, and the anode-active-material patches are spaced apart from one another along the length of the current-collector web with the inter-patch regions located therebetween.
13. The method of claim 12 , wherein each of the anode-active-material patches has a width in the same direction as the width of the current-collector web, and the width of each of the anode-active-materials is at least about 95% of the width of the current-collector web.
14. The method of claim 1 , wherein each electrical tab has a tab length, and the method further comprising spacing ones of the anode-active-material patches from one another by a minimum distance equal to or greater than the tab length.
15. The method of claim 1 , wherein the method is performed in a roll-to-roll process and the current-collector web is provided in a continuous ribbon.
16. The method of claim 1 , further comprising securing, on a second side of the current-collector web opposite the first side, additional metal foil to the current-collector web as reverse-side multiple anode-active-material patches spaced from one another and in registration with corresponding ones of the anode-active-material patches on the first side of the current-collector web.
17. The method of claim 1 , wherein each anode has an active area, and the method further comprises sizing a corresponding one of the anode-active-material patches to have an area at least equal to the active area of the anode.
18. The method of claim 1 , wherein the anodes are formed in a 1:1 ratio relative to the anode-active-material patches.
19. The method of claim 1 , wherein the anodes are formed in a 2:1 ratio relative to the anode-active-material patches.
20. The method of claim 1 , wherein each inter-patch region is used to form only a single electrical tab of a corresponding one of the anodes.
21. The method of claim 1 , wherein each inter-patch region is used to form at least two electrical tabs corresponding, respectively, to the ones of the anode-active-material patches defining that inter-patch region.
22. The method of claim 1 , wherein the metal foil comprises lithium, and at least some of the anodes each have a width of at least 20 mm and a length of at least 120 mm.
23. The method of claim 22 , wherein the current-collector web comprises copper.
24. The method of claim 22 , wherein the metal foil comprises lithium, and at least some of the anodes each have a width of at least 50 mm and a length of at least 150 mm.
25. The method of claim 1 , wherein the current-collector web comprises a solid metal foil.
26. The method of claim 1 , wherein the current-collector web comprises a perforated metal foil.
27. The method of claim 1 , wherein the current-collector web comprises a metal mesh.
28. The method of claim 1 , wherein the current-collector web has a thickness in a range of about 4 μm to about 10 μm.
29. The method of claim 28 , wherein the each anode-active-material patch has a thickness in a range of about 15 μm to about 25 μm.