Nonaqueous electrolyte secondary battery

Abstract

A nonaqueous electrolyte secondary battery comprising a negative electrode constituted of a carbonaceous material permitting reversible insertion and desorption of lithium, a positive electrode permitting reversible insertion and desorption of lithium, a separator separating these positive electrode and negative electrode from each other and a nonaqueous electrolyte composed of an organic solvent and, dissolved therein, a solute of lithium salt, wherein the nonaqueous electrolyte contains vinylene carbonate and di(2-propynyl) oxalate, these vinylene carbonate and di(2-propynyl) oxalate added in an amount of 0.1 to 3.0% by mass and 0.1 to 2.0% by mass, respectively, based on the mass of the nonaqueous electrolyte. Thus, there can be provided a nonaqueous electrolyte secondary battery wherein a stable SEI surface coating is formed to thereby exhibit a large initial capacity and excel in cycle characteristics at high temperature and wherein any cell swelling is slight.

Description

technical field [0001] The present invention relates to a non-aqueous electrolyte secondary battery, and more specifically, to a non-aqueous electrolyte secondary battery with a large initial capacity, excellent charge-discharge cycle characteristics at high temperature, and small battery expansion. Background technique [0002] With the rapid popularization of portable electronic devices, the requirements for the specifications of the batteries used in them are becoming stricter year by year, especially the requirements for small and thin, excellent cycle characteristics and stable performance at high capacity. However, in the field of secondary batteries, compared with other batteries, lithium non-aqueous electrolyte secondary batteries with high energy density have attracted people's attention. In the secondary battery market, the lithium non-aqueous electrolyte secondary batteries occupy The ratio shows a large increase. [0003] The lithium non-aqueous electrolyte seco...

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Problems solved by technology

[0009] On the other hand, the following Patent Document 3 indicates that when at least one of the alkyne derivatives represented by the following general formula (I) is added to the electrolytic solution, excellent charge-discharge cycle characteristics, battery capacity, storage characteristics, etc. can be obtained. The non-aqueous electrolyte secondary battery, however, gives good cycle characteristics up to 50 cycles at room temperature, and the long-term charge-discharge cycle characteristics of 300 cycles deteriorate, so there is no improvement in charge-discharge cycle characteristics at high temperatures

It can be considered that the SEI film formed by the alkyne derivative represented by the following general formula (I) is easily deteriorated during charge and discharge cycles or at high temperature, so the characteristics of the battery are reduced.

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