Lithium secondary batteries and nonaqueous electrolyte for use in the same
A lithium secondary battery comprising: a positive electrode and a negative electrode which each has a specific composition and specific properties; and a nonaqueous electrolyte which contains a cyclic siloxane compound represented by general formula (1), fluorosilane compound represented by general formula (2), compound represented by general formula (3), compound having an S—F bond in the molecule, nitric acid salt, nitrous acid salt, monofluorophosphoric acid salt, difluorophosphoric acid salt, acetic acid salt, or propionic acid salt in an amount of 10 ppm or more of the whole nonaqueous electrolyte. This lithium secondary battery has a high capacity, long life, and high output. [In general formula (1), R 1 and R 2 are an organic group having 1-12 carbon atoms and n is an integer of 3-10. In general formula (2), R 3 to R 5 are an organic group having 1-12 carbon atoms; x is an integer of 1-3; and p, q, and r each are an integer of 0-3, provided that 1≤p+q+r≤3. In general formula (3), R 6 to R 8 are an organic group having 1-12 carbon atoms and symbol A is a group constituted of H, C, N, O, F, S, Si, and/or P.]
1. A nonaqueous electrolyte for secondary battery comprising:
10 ppm to 5 mass percent of at least one specific compound from the group consisting of cyclic siloxane compounds represented by
wherein R 1 and R 2 may be the same or different and represent an organic group which has 1 to 12 carbon atoms and n represents an integer of 3 to 10; a fluorosilane having the formula
SiF x R 3 p R 4 q R 5 r (2)
wherein R 3 to R 5 may be the same or different and represent an organic group which has 1-12 carbon atoms; x represents an integer of 1-3; and p, q, and r each represents an integer of 0-3, provided that 1≤p+q+r≤3; and compounds having the formula (3):
wherein R 6 to R 8 may be the same or different and represent an organic group which has 1-12 carbon atoms and A represents at least one member selected from the group consisting of H, C, N, O, F, S, Si, and P; and
a non-aqueous solvent comprising from about 1 to 25 volume percent of ethylene carbonate based the total electrolyte volume.
2. The nonaqueous electrolyte for secondary battery of claim 1 comprising from about 1 to 20 volume percent of ethylene carbonate based on the total electrolyte volume.
3. The electrolyte of claim 2 wherein the non-aqueous solvent comprises from about 1 to 15 volume percent of ethylene carbonate based on the total electrolyte volume.
4. The electrolyte of claim 2 wherein the non-aqueous solvent comprises at least one chain carbonate.
5. The electrolyte of claim 4 wherein the chain carbonate is a dialkyl carbonate having 1— 5 carbons.
6. The electrolyte of claim 4 wherein the chain carbonate is at least one selected from the group consisting of dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, ethyl methyl carbonate, methyl n-propyl carbonate, and ethyl n-propyl carbonate.
7. The electrolyte of claim 6 wherein the chain carbonate is at least one selected from the group consisting of dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.
8. The electrolyte of claim 2 wherein the specific compound is at least one cyclic siloxane selected from the group consisting of:
wherein R 1 and R 2 may be the same or different and represent an organic group which has 1 to 12 carbon atoms and n represents an integer of 3 to 10.
9. The electrolyte of claim 2 wherein the specific compound is at least one fluorosilane selected from the group consisting of
SiF x R 3 p R 4 q R 5 r (2)
wherein R 3 to R 5 may be the same or different and represent an organic group which has 1-12 carbon atoms; x represents an integer of 1-3; and p, q, and r each represents an integer of 0-3, provided that 1≤p+q+r≤3; and compounds having the formula (3)
10. The electrolyte of claim 1 wherein the specific compound is at least one compound selected from the group consisting of
wherein R 6 to R 8 may be the same or different and represent an organic group which has 1-12 carbon atoms and A represents at least one member selected from the group consisting of H, C, N, O, F, S, Si, and P.
11. The electrolyte of claim 2 wherein the specific compound comprises from 0.01 mass percent to 5 mass percent of the non-aqueous electrolyte.
12. The electrolyte of claim 2 wherein the specific compound comprises from 0.01 mass percent to 4 mass percent of the non-aqueous electrolyte.
13. The electrolyte of claim 2 wherein the specific compound comprises from 0.01 mass percent to 3 mass percent of the non-aqueous electrolyte.
14. The electrolyte of claim 1 wherein the specific compound comprises from 0.05 mass percent to 5 mass percent of the non-aqueous electrolyte.
15. The electrolyte of claim 4 wherein the specific compound comprises from 0.05 mass percent to 4 mass percent of the non-aqueous electrolyte.
16. The electrolyte of claim 5 wherein the specific compound comprises from 0.05 mass percent to 3 mass percent of the non-aqueous electrolyte.
17. The electrolyte of claim 1 wherein the specific compound comprises from 0.1 mass percent to 5 mass percent of the non-aqueous electrolyte.
18. The electrolyte of claim 1 wherein the specific compound comprises from 0.1 mass percent to 4 mass percent of the non-aqueous electrolyte.
19. The electrolyte of claim 1 wherein the specific compound comprises from 0.1 mass percent to 3 mass percent of the non-aqueous electrolyte.
20. The electrolyte of claim 8 wherein the specific compound is at least compound selected from the group consisting of hexaphenylcyclotrisiloxane, 1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and hexamethylcyclotrisiloxane.
21. The electrolyte of claim 9 wherein the specific compound is at least compound selected from the group consisting of tripropylfluorosilane, phenyldimethylfluorosilane, triphenylfluorosilane, vinyldimethylfluorosilane, vinyldiethylfluorosilane, vinyldiphenylfluorosilane, trimethoxyfluorosilane, triethoxyfluorosilane, dimethyldifluorosialne, diethyldifluorosilane, divinyldifluorosilane, and ethylvinyldifluorosilane, methyltrifluorosilane and ethyltrifluorosilane.
22. The electrolyte of claim 9 wherein the specific compound is at least compound selected from the group consisting of hexaethyldisiloxane, octamethyltrisiloxane,
methoxytrimethylsilane, ethoxytrimethylsilane, bis(trimethylsilyl) peroxide, trimethylsilyl acetate, triethylsilyl acetate, trimethylsilyl propionate, trimethylsilyl methacrylate, trimethylsilyl trifluoroacetate, trimethylsilyl methanesulfonate, trimethylsilyl ethanesulfonate, triethylsilyl methanesulfonate, and trimethylsilyl fluoromethanesulfonate, bis(trimethylsilyl) sulfate, tris(trimethylsiloxy)boron, tris(trimethylsilyl) phosphate, and tris(trimethylsilyl) phosphite.
23. A lithium secondary battery comprising:
a positive electrode, a negative electrode each capable of occluding and releasing lithium ions;
a microporous film separator interposed between the electrodes; and
the non-aqueous electrolyte of claim 1 .