Silicon-contained material, negative electrode for use in non-aqueous electrolyte secondary battery, method of producing the same, non-aqueous electrolyte secondary battery, and method of producing the same

A silicon-contained material capable of being doped with lithium and de-doped, wherein

• when a three-electrode cell produced by using a working electrode including the silicon-contained material as an active material, a reference electrode made of metallic lithium, a counter electrode made of metallic lithium, and an electrolyte having lithium ionic conductivity is charged and discharged to graph a relationship between a derivative dQ/dV of a charging or discharging capacity Q with respect to an electric potential V of the working electrode on the basis of the reference electrode and the electric potential V, a ratio B/A is 2 or less while current flows in a direction in which the lithium of the silicon-contained material is de-doped in the discharge, where A is the maximum value of the derivative dQ/dV with respect to a potential range from 260 mV to 320 mV, and B is the maximum value of the derivative dQ/dV with respect to a potential range from 420 mV to 520 mV.

A method of producing a negative electrode for use in a non-aqueous electrolyte secondary battery by using a silicon-contained material capable of being doped with lithium and de-doped as a negative electrode active material, comprising:

• selecting the silicon-contained material such that when a three-electrode cell produced by using a working electrode including the silicon-contained material as an active material, a reference electrode made of metallic lithium, a counter electrode made of metallic lithium, and an electrolyte having lithium ionic conductivity is charged and discharged to graph a relationship between a derivative dQ/dV of a charging or discharging capacity Q with respect to an electric potential V of the working electrode on the basis of the reference electrode and the electric potential V, a ratio B/A is 2 or less while current flows in a direction in which the lithium of the silicon-contained material is de-doped in the discharge, where A is the maximum value of the derivative dQ/dV with respect to a potential range from 260 mV to 320 mV, and B is the maximum value of the derivative dQ/dV with respect to a potential range from 420 mV to 520 mV;
• and
• producing the negative electrode for use in a non-aqueous electrolyte secondary battery by using the selected silicon-contained material as the negative electrode active material.