NEGATIVE ELECTRODE MATERIAL FOR LITHIUM ION SECONDARY BATTERIES, NEGATIVE ELECTRODE FOR LITHIUM ION SECONDARY BATTERIES, LITHIUM ION SECONDARY BATTERY; METHOD FOR PRODUCING NEGATIVE ELECTRODE MATERIAL FOR LITHIUM ION SECONDARY BATTERIES, AND METHOD FOR PRODUCING NEGATIVE ELECTRODE FOR LITHIUM ION SECONDARY BATTERIES

摘要

Provided is a lithium secondary battery which is reduced in deterioration over time with respect to the battery performance. A negative electrode material for lithium ion secondary batteries, which contains a negative electrode active material and a coating agent that is immobilized on the negative electrode active material. The coating agent contains boron and an alkali metal element, and the coating agent is immobilized on the negative electrode active material by reacting the coating agent with surface functional groups of the negative electrode active material. The coating agent is exemplified by trimethyl borate and the like. A lithium ion secondary battery which uses the negative electrode material for lithium ion secondary batteries.