Lithium secondary battery

Patent metadata

Field	Value
Publication number	US-2019363396-A1
Application number	US-201716332839-A
Country	US
Kind code	A1
Filing date	Aug 4, 2017
Priority date	Sep 14, 2016
Publication date	Nov 28, 2019
Grant date	—

Abstract

A lithium secondary battery having a positive electrode comprises a solid solution of Li 2 MnO 3 and LiMO 2 ; a negative electrode comprises at least one negative electrode active material selected from the group consisting of metal silicon, alloys comprising silicon and silicon oxides represented by a composition formula SiO x where 0<x≤2, and a polyacrylic acid; and an electrolyte solution comprises an electrolyte solvent comprising a cyclic carbonate, a fluorine-containing phosphate ester and a fluorine-containing ether, and a supporting salt comprising Li, wherein an amount of the cyclic carbonate is 10 volume % or more and less than 40 volume %, an amount of the fluorine-containing phosphate ester is 20 volume % or more and 50 volume % or less, and an amount of the fluorine-containing ether is 25 volume % or more and 70 volume % or less with respect to a total amount of the cyclic carbonate, the fluorine-containing phosphate ester and the fluorine-containing ether.

First claim

1 . A lithium secondary battery,
wherein a positive electrode comprises a positive electrode active material represented by the following formula (1) or (2); a negative electrode comprises at least one negative electrode active material selected from the group consisting of metal silicon, alloys comprising silicon and silicon oxides represented by a composition formula SiO x where 0<x≤2, and a polyacrylic acid; and an electrolyte solution comprises an electrolyte solvent comprising a cyclic carbonate, a fluorine-containing phosphate ester and a fluorine-containing ether, and a supporting salt comprising Li, wherein an amount of the cyclic carbonate is 10 volume % or more and less than 40 volume %, an amount of the fluorine-containing phosphate ester is 20 volume % or more and 50 volume % or less, and an amount of the fluorine-containing ether is 25 volume % or more and 70 volume % or less with respect to a total amount of the cyclic carbonate, the fluorine-containing phosphate ester and the fluorine-containing ether,
xLi 2 MnO 3 —(1—x)LiMO 2   (1)

wherein x is in a range of 0.1<x<0.8, and M is at least one element selected from the group consisting of Mn, Fe, Co, Ni, Ti, Al and Mg, and
Li(Li x M 1−x−y Mn y )O 2   (2)

wherein x and y are in ranges of 0.1≤x≤0.3 and 0.33≤y≤0.8, and M is at least one element selected from the group consisting of Fe, Co, Ni, Ti, Al and Mg.

2 . The lithium secondary battery according to claim 1 , wherein a total volume of the fluorine-containing phosphate ester and the fluorine-containing ether is larger than a volume of the cyclic carbonate.

3 . The lithium secondary battery according to claim 1 , wherein an amount of the fluorine-containing ether is more than 50 volume % with respect to a total amount of the cyclic carbonate and the fluorine-containing ether.

4 . The lithium secondary battery according to claim 1 , wherein an amount of the supporting salt comprising Li is 0.4 mol or more and 1.5 mol or less relative to 1 L of the electrolyte solvent.

5 . The lithium secondary battery according to claim 1 , wherein the supporting salt comprising Li comprises LiN(FSO 2 ) 2 .

6 . The lithium secondary battery according to claim 5 , wherein an amount of LiN(FSO 2 ) 2 is 20 mol % or more and 80 mol % or less with respect to a total amount of the supporting salt containing Li.

7 . The lithium secondary battery according to claim 1 , wherein the cyclic carbonate is at least one selected from the group consisting of ethylene carbonate, propylene carbonate, vinylene carbonate, and compounds in which at least part of hydrogen atoms thereof are replaced with fluorine atoms.

8 . The lithium secondary battery according to claim 1 , wherein the fluorine-containing phosphate ester is represented by the following formula (3),
O═P(—O—R 1 ′)(—O—R 2 ′)(—O—R 3 ′)  (3)
wherein R 1 ′, R 2 ′ and R 3 ′ each independently represent alkyl group or fluorine-containing alkyl group; and at least one of R 1 ′, R 2 ′ and R 3 ′ is fluorine-containing alkyl group.

9 . The lithium secondary battery according to claim 1 , wherein the fluorine-containing ether is represented by the following formula (4),
C n H 2n+1−1 F 1 —O—C m H 2m+l−k F k   (4)
wherein n is 1, 2, 3, 4, 5 or 6, m is 1, 2, 3 or 4, l is an integer of 0 to 2n+1, k is an integer of 0 to 2m+1, and at least one of l and k is 1 or more.

10 . The lithium secondary battery according to claim 1 , wherein the amount of the cyclic carbonate is 15 volume % or more and 25 volume % or less with respect to the total amount of the cyclic carbonate, the fluorine-containing phosphate ester and the fluorine-containing ether.

11 . A method for manufacturing a lithium secondary battery, comprising the steps of:
fabricating an electrode element by stacking a negative electrode and a positive electrode via a separator, and encapsulating the electrode element and an electrolyte solution into an outer package, wherein the positive electrode comprises a positive electrode active material represented by the following formula (1) or (2); the negative electrode comprises at least one negative electrode active material selected from the group consisting of metal silicon, alloys comprising silicon and silicon oxides represented by a composition formula SiO x where 0<x≤2, and a polyacrylic acid; and the electrolyte solution comprises an electrolyte solvent comprising a cyclic carbonate, a fluorine-containing phosphate ester and a fluorine-containing ether, and a supporting salt comprising Li, wherein an amount of the cyclic carbonate is 10 volume % or more and less than 40 volume %, an amount of the fluorine-containing phosphate ester is 20 volume % or more and 50 volume % or less, and an amount of the fluorine-containing ether is 25 volume % or more and 70 volume % or less with respect to a total amount of the cyclic carbonate, the fluorine-containing phosphate ester and the fluorine-containing ether,
xLi 2 MnO 3 —(1—x)LiMO 2   (1)

wherein x is in a range of 0.1<x<0.8, and M is at least one element selected from the group consisting of Mn, Fe, Co, Ni, Ti, Al and Mg, and
Li(Li x M 1−x−y Mn y )O 2   (2)

wherein x and y are in ranges of 0.1≤x≤0.3 and 0.33≤y≤0.8, and M is at least one element selected from the group consisting of Fe, Co, Ni, Ti, Al and Mg.

Assignees

• Nec Corp

Inventors

• Hasegawa Takuya

Classifications

• H01M4/386

  Silicon or alloys based on silicon · CPC title

• H01M4/483

  for non-aqueous cells (H01M4/485 takes precedence) · CPC title

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M4/505

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title

• H01M10/0525 Primary

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title