Non-aqueous electrolyte solution and electricity-storage device using same

Abstract

The present invention comprises: a non-aqueous electrolyte solution that produces improved electrochemical properties in high-temperature environments and is characterized by containing at least one organic phosphorus compound represented by general formula (I); an electricity-storage device using said non-aqueous electrolyte solution; and a specific organic phosphorus compound. In the formula, R1 and R2 each independently represent an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an alkoxy group, a cycloalkoxy group, an alkenyloxy group, an alkynyloxy group, an alkyl-halide group, an alkoxy-halide group, an aryl group, or an aryloxy group; R3 and R4 each independently represent a hydrogen atom, a halogen atom, or an alkyl group; m represents an integer from 1 to 4; n represents 0 or 1; q represents 1 or 2; if q is 1 and n is 0, X represents an alkoxy group, an alkynyloxy group, an alkyloxy-alkoxy group, an aryloxy group, or the like; if q is 1 and n is 1, X represents an alkyl group, an alkynyl group, an alkoxy group, an alkynyloxy group, an alkyloxy-alkoxy group, or the like; and if q is 2, X represents -O-L3-O-, -OC(=O)-C(=O)O-, or a single bond.

Description

technical field [0001] The present invention relates to a nonaqueous electrolytic solution capable of improving electrochemical properties at high temperatures, an electrical storage device using the nonaqueous electrolytic solution, and a specific organic phosphorus compound. Background technique [0002] In recent years, power storage devices, particularly lithium secondary batteries, have been widely used as power sources for electronic devices such as mobile phones and notebook personal computers, or as power sources for electric vehicles and power storage. Batteries mounted in these electronic devices or automobiles are likely to be used in high summer temperatures or in environments warmed by heat from electronic devices. [0003] A lithium secondary battery as a type of storage device is mainly composed of a positive electrode and a negative electrode containing a material that can intercalate and deintercalate lithium, and a non-aqueous electrolyte solution containin...

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Problems solved by technology

The above-mentioned negative electrode materials have the following problems: since lithium and electrons are intercalated and deintercalated at the same extremely low potential as lithium metal, most of the solvent may be reductively decomposed especially at high temperatures, regardless of the negative electrode material. Regardless of the type, partial reduction and decomposition of the solvent in the electrolyte will occur on the negative electrode. Due to the deposition of decomposition products and gas generation, the movement of lithium ions will be hindered, which will reduce battery characteristics such as cycle characteristics at high temperatures.

In addition, for lithium secondary batteries that use lithium metal or its alloys, metal simple substances such as tin or silicon, or oxides as negative electrode materials, it is known that although the initial capacity is high, micronization occurs during cycles, so it is not compatible with carbon materials. Compared with the negative electrode, the reductive decomposition of the non-aqueous solvent is accelerated, and the battery performance such as battery capacity and cycle characteristics at high temperature is greatly reduced.

[0005] On the other hand, for LiCoO that can be used as a cathode material 2 , LiMn 2 o 4 , LiNiO 2 、LiFePO 4 Materials that can intercalate and deintercalate lithium, such as lithium, have the following problems: since lithium and electrons are intercalated and deintercalated at a high voltage of 3.5 V or more based on lithium, most of the solvent may be lost, especially at high temperatures. Due to oxidative decomposition, regardless of the type of positive electrode material, partial oxidative decomposition of the solvent in the electrolyte will occur on the positive electrode, and due to the deposition of decomposition products and gas generation, the movement of lithium ions is hindered, resulting in degradation of battery characteristics such as cycle characteristics

Therefore, the current situation is that a little decomposition of the non-aqueous electrolyte will easily reduce the performance of the battery at high temperature

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