SILICON-BASED ALLOY NEGATIVE ELECTRODE MATERIAL FOR ELECTRIC POWER STORAGE DEVICE, AND ELECTRODE ARRANGED BY USE THEREOF

摘要

PROBLEM TO BE SOLVED: To provide a Si-based alloy negative electrode material and an electrode which can materialize excellent battery characteristics by: the scale-down in structure; excellent ion conductivity and electron conductivity; the control of a component capable of increasing the effect of relaxing a stress; and the control of the sizes of crystallite of a Si phase and an intermetallic compound phase.SOLUTION: A negative electrode material made of a Si-based alloy for an electric power storage device in which lithium ion transfer is caused in charge and discharge thereof comprises: a Si primary phase made of Si; and a compound phase including Si and at least one element other than Si. The compound phase has a phase which includes a phase including a combination of Si and Cr, or a combination of Si, Cr and Ti. The Si primary phase has a size of Si crystallite of 30 nm or smaller. The compound phase including the combination of Si and Cr, or the combination of Si, Cr and Ti has a size of crystallite of 40 nm or smaller.