Battery having improved positive electrode and method of manufacturing the same
View Patent ↗There is provided a battery containing an electrolyte, according to which oxidative decomposition of the electrolyte is suppressed. The battery contains a positive electrode having an active material and an electron conducting material. The electron conducting material has a barrier layer at least on the surface thereof. This barrier layer is substantially constituted from at least one material selected from (a) oxides of elements in group 2 to 14 and the third or subsequent period of the periodic table, (b) carbides of elements in group 2 to 14 and the third or subsequent period of the periodic table, (c) nitrides of elements in group 2 to 14 and the third or subsequent period of the periodic table, and (d) tungsten.
1. A battery comprising:
a molten salt electrolyte that exhibits a liquid state in at least part of a temperature range between 10 and 40 degrees C.; and
a positive electrode having a mixture of an active material and an electron conducting material, said mixture being supported on an electrically conducting member;
wherein said electron conducting material is in particulate form and has at least on a surface thereof a separate barrier layer substantially constituted from at least one material selected from the group consisting of:
(a) oxides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof;
(b) nitrides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof; and
(c) tungsten,
wherein the barrier layer decreases an oxidative decomposition of the electrolyte.
2. The battery according to claim 1 , wherein said barrier layer contains an oxide having at least one metal which belongs to group 4 to 14 of the periodic table as a constituent element thereof.
3. The battery according to claim 2 , wherein said barrier layer contains an oxide having at least one metal which belongs to group 4 to 6 of the periodic table as a constituent element thereof.
4. The battery according to claim 3 , wherein said barrier layer is substantially consisting of a titanium oxide.
5. The battery according to claim 2 , wherein said barrier layer contains an oxide having at least one metal which belongs to group 13 or 14 of the periodic table as a constituent element thereof.
6. The battery according to claim 5 , wherein said barrier layer is substantially consisting of an indium-tin oxide.
7. The battery according to claim 1 , wherein said barrier layer contains a carbide having at least one metal which belongs to group 4 to 14 of the periodic table as a constituent element thereof.
8. The battery according to claim 7 , wherein said barrier layer contains a carbide having at least one metal which belongs to group 4 to 6 of the periodic table as a constituent element thereof.
9. The battery according to claim 8 , wherein said barrier layer is substantially consisting of a titanium carbide.
10. The battery according to claim 8 , wherein said barrier layer is substantially consisting of a tantalum carbide and/or iron nitride.
11. The battery according to claim 1 , wherein the material constituting said barrier layer has a lower activity than at least carbon to oxidative decomposition of said electrolyte.
12. The battery according to claim 1 , wherein the material constituting said barrier layer is electrically conductive.
13. The battery according to claim 1 , wherein the material constituting the interior of said electron conducting material is electrically conductive carbon.
14. The battery according to claim 1 , wherein the material constituting the interior of said electron conducting material is a metal.
15. The battery according to claim 1 , wherein said active material of said positive electrode is substantially consisting of a composite oxide having lithium and a transition metal as constituent elements thereof.
16. The battery according to claim 15 , wherein said active material of said positive electrode is substantially consisting of a composite oxide having lithium, nickel and manganese as constituent elements thereof.
17. The battery according to claim 1 , wherein said positive electrode has an active material able to make the electric potential of said positive electrode at least 4.5 V higher than the electric potential of metallic lithium.
18. The battery according to claim 1 , wherein said electrolyte is a molten salt, and the cation in said molten salt is at least one cation selected from an imidazolium ion, art ammonium ion and a sulfonium ion.
19. The battery according to claim 1 , wherein the principal component of said electrolyte is a molten salt.
20. The battery according to claim 19 , wherein said electrolyte contains a lithium salt as a supporting electrolyte.
21. The battery according to claim 1 , further comprising a negative electrode having an active material able to absorb and release lithium ions.
22. The battery according to claim 21 , wherein said negative electrode has an active material able to maintain the electric potential of said negative electrode at 1 V or more higher than the potential of metallic lithium.
23. The battery according to claim 22 , wherein said active material of said negative electrode is substantially consisting of a lithium titanate represented by Li4Ti5O12.
24. A method of manufacturing a battery comprising the steps of:
preparing an electron conducting material having at least on a surface thereof a separate barrier layer substantially constituted from at least one material selected from the group consisting of (a) oxides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof;
(b) nitrides having at least one element which belongs to group 2 to 14 in the third or subsequent period of the periodic table as a constituent element thereof; and (c) tungsten, the electron conducting material being in particulate form;
manufacturing a positive electrode using said electron conducting material and a positive electrode active material; and
constructing the battery using said positive electrode, a molten salt electrolyte that exhibits a liquid state in at least part of a temperature range between 10 and 40 degrees C., and a negative electrode, wherein the barrier layer decreases an oxidative decomposition of the electrolyte.
25. The method according to claim 24 , wherein said electron conducting material is obtained by attaching nanoparticles consisting substantially of said material selected from the group (a) to (c) onto the surface of carbon particles and/or metal particles so as to form said barrier layer on the surface of said particles.