LITHIUM-ION SECONDARY BATTERY, NEGATIVE ELECTRODE FOR LITHIUM-ION SECONDARY BATTERY, POWER TOOL, ELECTRIC VEHICLE AND POWER STORAGE SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a lithium-ion secondary battery in which cycle characteristics and initial charge-discharge characteristics can be improved.SOLUTION: The lithium-ion secondary battery includes a positive electrode 21, a negative electrode 22, and an electrolytic solution, and a separator 23 provided between the positive electrode 21 and the negative electrode 22 is impregnated with the electrolytic solution. The negative electrode 22 has a negative electrode active material layer 22B including a plurality of negative electrode active material particles, and the negative electrode active material particles include a core section and a coating section coating at least a part of a surface of the core section. The core section includes a silicon-based material (SiO:0≤x0.5), and the coating section includes an amorphous or low-crystalline silicon-based material (SiO:0.5≤y≤1.8).