Electrolytic solution, electrochemical device, lithium ion secondary battery, and module

Abstract

The purpose of the present invention is to provide: an electrolytic solution which enables the production of a secondary battery having excellent oxidation resistance and excellent storage stability at higher temperatures or the like; an electrochemical device such as a lithium ion secondary battery, in which the electrolytic solution is used; and a module in which the electrochemical device is used. The present invention is an electrolytic solution comprising a solvent and an electrolyte salt, said electrolytic solution being characterized in that the solvent comprises a fluorinated compound (A) represented by general formula (1) and a fluorinated compound (B) represented by general formula (2), wherein the content of the fluorinated compound (A) is 0.01 to 20 mass% in the solvent and the content of the fluorinated compound (B) is 10 to 80 mass% in the solvent. Rf1OCOOR (1) (wherein Rf1 represents a fluorinated alkyl group having 1 to 4 carbon atoms; and R represents a non-fluorinated alkyl group having 1 to 4 carbon atoms); and Rf2OCOORf3 (2) (wherein Rf2 and Rf3 are the same as or different from each other and independently represent a fluorinated alkyl group having 1 to 4 carbon atoms).

Description

technical field [0001] The invention relates to an electrolyte solution, an electrochemical device, a lithium ion secondary battery and components. Background technique [0002] In recent years, with the reduction in weight and size of electrical products, development of lithium ion secondary batteries having high energy density has been progressing. In addition, as the fields of application of lithium-ion secondary batteries expand, improvements in battery characteristics are urgently desired. Especially when lithium-ion secondary batteries are used in automotive applications in the future, safety and battery characteristics are becoming more and more important. [0003] However, since lithium-ion secondary batteries cannot be said to be sufficient in terms of safety when the battery is overcharged, internally short-circuited, and stabbed, etc. In this case, a battery with higher safety is required. In addition, in the case of in-vehicle use, in order to increase the cap...

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Problems solved by technology

Patent Document 2 describes that diols or monoalcohols contained in a high dielectric constant solvent such as ethylene carbonate or a low viscosity solvent such as dimethyl carbonate react slowly with a fluorine-containing electrolyte at room temperature to generate HF , and thus the HF in the electrolyte increases with the passage of time, reducing the cycle characteristics of the battery

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