Lithium ion secondary battery, lithium ion secondary battery negative electrode, battery pack, electric vehicle, electricity storage system, power tool, and electronic apparatus

摘要

A lithium ion secondary battery is provided with a positive electrode, a negative electrode containing an active material, and an electrolytic solution, wherein the active material includes a core portion capable of occluding and releasing lithium ions, an amorphous or low-crystalline coating portion disposed on at least a part of the surface of the core portion, and a fibrous carbon portion disposed on at least a part of the surface of the coating portion, and the coating portion contains Si and O as constituent elements, while the atomic ratio y (O/Si) of O relative to Si satisfies 0.5≦y≦1.8.

主权项

1. A lithium ion secondary battery comprising:
a positive electrode; a negative electrode containing an active material; and an electrolytic solution, wherein the active material includes:
a core portion capable of occluding and releasing lithium ions;an amorphous or low-crystalline SiOy coating portion disposed on at least a part of a surface of the core portion; anda fibrous carbon portion disposed on at least a part of a surface of the SiOy coating portion, wherein y is an atomic ratio of O relative to Si (O/Si) and satisfies 0.5≦y≦1.8, and wherein an average length of the fibrous carbon portion is 50 nm to 50,000 nm.