Non-aqueous electrolyte secondary battery

Abstract

The present invention relates to a nonaqueous electrolyte secondary battery having a long cycling life even when it is charged at a positive electrode charging potential of 4.4 to 4.6 V based on lithium and further having a high residual capacity after storage at high temperature in a charged state, characterized in that: a positive electrode active material is composed of a mixture of a lithium-cobalt composite oxide containing at least both zirconium and magnesium, and a lithium-manganese-nickel composite oxide containing at least both manganese and nickel, the nonaqueous electrolyte including fluoroethylene carbonate and dimethyl carbonate as a nonaqueous solvent and further including an additive expressed by General Formula (1): (where R is a methyl group or a hydrogen atom, m is 0 or 1, and n is 1 or 2), and the positive electrode having a charging potential of 4.4 to 4.6 V based on lithium.

Description

Non-aqueous electrolyte secondary battery technical field The present invention relates to a non-aqueous electrolyte secondary battery, in particular to a non-aqueous electrolyte secondary battery which has a long cycle life even when the charging potential of the positive electrode is set to 4.4 to 4.6 V on the basis of lithium and is charged. Moreover, the residual capacity rate after high-temperature charging and storage is large. Background technique It is widely used as a drive power source for portable electronic devices such as mobile phones, portable personal computers, and portable music players, and as a power source for hybrid electric vehicles (HEV) or electric vehicles (EV). Lithium-ion secondary batteries having high energy density and high capacity are representative non-aqueous electrolyte secondary batteries. As the positive electrode active material of these non-aqueous electrolyte secondary batteries, LiMO, which can reversibly store and release lithiu...

AI Technical Summary

Problems solved by technology

However, even if VC for repairing is added, when the charging potential of the positive electrode of the non-aqueous electrolyte secondary battery is increased from the conventional 4.3 V to 4.4 V or more on the basis of lithium, it is not possible to satisfy the high-temperature charge storage characteristics. Battery

This is considered to be caused by the fact that VC for repair is oxidized on the positive electrode side since the positive electrode potential is set to a high potential, and VC itself becomes a cause of self-discharge.

According to this phenomenon, when using a positive electrode active material that can ensure oxidation resistance as described above, and a non-aqueous electrolyte solution that combines fluorinated ethylene carbonate and a chain carbonate, the charge potential of the positive electrode is calculated on the basis of lithium In non-aqueous electrolyte secondary batteries set at 4.4V or higher, it is very difficult to balance cycle performance and high-temperature charge storage characteristics

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