Nonaqueous electrolyte secondary cell, power supply comprising the secondary cell, portable device, transportable or movable machine, electric apparatus for home use, and method for charging nonaqueous electrolyte secondary cell

摘要

A nonaqueous electrolyte secondary battery is made up of a positive electrode and a negative electrode which are composed of a lithium ion-occluding and releasing material and a binder polymer, at least one separator for separating the positive and negative electrodes, and a nonaqueous electrolyte which is composed of a lithium salt and an organic solvent. The electrolyte includes also a substance which is oxidized at the positive electrode at a cell voltage of from 4.1 V to 5.2 V, and which provokes an oxidation reaction that differs from the lithium-releasing reaction. The presence of this substance improves the overcharge characteristics and safety of the nonaqueous electrolyte secondary battery.