US-20260128376-A1 - NONAQUEOUS ELECTROLYTE ENERGY STORAGE DEVICE

Abstract

A nonaqueous electrolyte energy storage device according to one aspect of the present invention includes: a negative electrode including a negative active material layer; and a nonaqueous electrolyte containing an unsaturated cyclic carbonate and a P—O bond-containing fluorophosphate, in which the negative active material layer has a BET specific surface area of 0.80 m 2 /g or more and 1.5 m 2 /g or less, and the ratio of the content of the unsaturated cyclic carbonate to the total content of the unsaturated cyclic carbonate and the P—O bond-containing fluorophosphate is 0.60 or more and less than 1.0 on a mole basis.

Inventors

• Keiji Shimomura

Assignees

• GS YUASA INTERNATIONAL LTD.

Dates

Publication Date

20260507

Application Date

20230921

Priority Date

20221004

Claims (4)

1. 1 . A nonaqueous electrolyte energy storage device, comprising: a negative electrode including a negative active material layer; and a nonaqueous electrolyte containing an unsaturated cyclic carbonate and a P—O bond-containing fluorophosphate, wherein the negative active material layer has a BET specific surface area of 0.80 m 2 /g or more and 1.5 m 2 /g or less, and a ratio of a content of the unsaturated cyclic carbonate to a total content of the unsaturated cyclic carbonate and the P—O bond-containing fluorophosphate is 0.60 or more and less than 1.0 on a mole basis.
2. 2 . The nonaqueous electrolyte energy storage device according to claim 1 , wherein a content of the unsaturated cyclic carbonate in the nonaqueous electrolyte is 1.4×10 −4 mol/dm 3 or more and 2.8×10 −4 mol/dm 3 or less.
3. 3 . The nonaqueous electrolyte energy storage device according to claim 1 , wherein a content of the P—O bond-containing fluorophosphate in the nonaqueous electrolyte is 1.1×10 −4 mol/dm 3 or less.
4. 4 . The nonaqueous electrolyte energy storage device according to claim 1 , wherein the unsaturated cyclic carbonate is vinylene carbonate, and the P—O bond-containing fluorophosphate is lithium difluorophosphate.

Description

TECHNICAL FIELD The present invention relates to a nonaqueous electrolyte energy storage device. BACKGROUND ART Nonaqueous electrolyte secondary batteries typified by lithium ion nonaqueous electrolyte secondary batteries are widely used in electronic devices such as personal computers and communication terminals, motor vehicles, and the like because the batteries are high in energy density. The nonaqueous electrolyte secondary batteries generally include an electrode assembly including a pair of electrodes electrically isolated by a separator, and a nonaqueous electrolyte interposed between the electrodes, and are configured to be charged and discharged by transferring charge carrier ions between both the electrodes. In addition, capacitors such as lithium ion capacitors and electric double-layer capacitors are also widely in use as nonaqueous electrolyte energy storage devices other than the nonaqueous electrolyte secondary batteries. In general, the nonaqueous electrolyte of the nonaqueous electrolyte energy storage device contains a nonaqueous solvent and an electrolyte salt dissolved in the nonaqueous solvent. In this nonaqueous electrolyte, various additives and solvents are selected and used for improved performance. PRIOR ART DOCUMENT Patent Document Patent Document 1: JP-A-2015-162304 SUMMARY OF THE INVENTION Problems to be Solved by the Invention In recent years, there has been a demand for a nonaqueous electrolyte energy storage device which has a higher capacity retention ratio after charge-discharge cycles and superior power performance in a low temperature environment. Patent Document 1 proposes improving a capacity retention ratio after charge-discharge cycles by devising components contained in an electrolyte solution. However, such a technique is insufficient to satisfy the required level regarding the capacity retention ratio after charge-discharge cycles and the power performance in a low temperature environment, and there is still room for improvement. An object of the present invention is to provide a nonaqueous electrolyte energy storage device having an excellent capacity retention ratio after charge-discharge cycles and excellent power performance in a low temperature environment. Means for Solving the Problems A nonaqueous electrolyte energy storage device according to one aspect of the present invention includes: a negative electrode including a negative active material layer; and a nonaqueous electrolyte containing an unsaturated cyclic carbonate and a P—O bond-containing fluorophosphate, in which the negative active material layer has a BET specific surface area of 0.80 m2/g or more and 1.5 m2/g or less, and the ratio of the content of the unsaturated cyclic carbonate to the total content of the unsaturated cyclic carbonate and the P—O bond-containing fluorophosphate is 0.60 or more and less than 1.0 on a mole basis. Advantages of the Invention The nonaqueous electrolyte energy storage device according to one aspect of the present invention can provide a nonaqueous electrolyte energy storage device having an excellent capacity retention ratio after charge-discharge cycles and excellent power performance in a low temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective oblique view illustrating an embodiment of a nonaqueous electrolyte energy storage device. FIG. 2 is a schematic view illustrating an embodiment of an energy storage apparatus configured by assembling a plurality of nonaqueous electrolyte energy storage devices. MODE FOR CARRYING OUT THE INVENTION First, the outline of a nonaqueous electrolyte energy storage device disclosed in the present specification is described. [1] A nonaqueous electrolyte energy storage device according to one aspect of the present invention includes: a negative electrode including a negative active material layer; and a nonaqueous electrolyte containing an unsaturated cyclic carbonate and a P—O bond-containing fluorophosphate, in which the negative active material layer has a BET specific surface area of 0.80 m2/g or more and 1.5 m2/g or less, and the ratio of the content of the unsaturated cyclic carbonate to the total content of the unsaturated cyclic carbonate and the P—O bond-containing fluorophosphate is 0.60 or more and less than 1.0 on a mole basis. When the BET specific surface area of the negative active material layer and the mole ratio of the unsaturated cyclic carbonate and the P—O bond-containing fluorophosphate are each in a specific range, the nonaqueous electrolyte energy storage device described in the above [1] has an excellent capacity retention ratio after charge-discharge cycles and excellent power performance in a low temperature environment. The reason for this is not clear, but is presumed as follows. In the nonaqueous electrolyte of the nonaqueous electrolyte energy storage device, an unsaturated cyclic carbonate which is decomposed during charge to form a coating film on the particle surfac