LITHIUM ION SECONDARY BATTERY

摘要

The purpose of this embodiment is to provide a lithium ion secondary battery that uses a 5 V class positive electrode, gas generation being reduced in said lithium ion secondary battery. Said embodiment is a lithium ion secondary battery provided with at least a positive electrode and an electrolyte, and being characterized by: the positive electrode containing a positive electrode active material having an operating potential of at least 4.5 V versus metallic lithium; and the electrolyte containing a polymer containing a cyano group.