Silicon oxide particles, making method, lithium ion secondary battery, and electrochemical capacitor

摘要

Silicon oxide particles each comprising an inner portion having an iron content of 10-1,000 ppm and an outer portion having an iron content of up to 30 ppm are suitable as negative electrode active material in nonaqueous electrolyte secondary batteries. Using a negative electrode comprising the silicon oxide particles as active material, a lithium ion secondary battery or electrochemical capacitor having a high capacity and improved cycle performance can be constructed.

主权项

1. A lithium ion secondary battery comprising a positive electrode, a negative electrode, and a lithium ion-conducting nonaqueous electrolyte, said negative electrode comprising a silicon oxide particles as negative electrode active material having an average particle size of 0.1 to 30 μm and a BET specific surface area of 0.5 to 30 m2/g, wherein a first iron content of inner portion of the silicon oxide particles is 15 to 1,000 ppm, and a second iron content of outer portion of the silicon oxide particles is 4 to 10 ppm, and
wherein the inner portion is different from the outer portion.