Si-BASED ALLOY NEGATIVE ELECTRODE MATERIAL FOR ELECTRICITY STORAGE DEVICES AND ELECTRODE USING SAME

摘要

The present invention provides: an Si-based alloy negative electrode material which enables the achievement of excellent battery characteristics; and an electrode. This negative electrode material is a negative electrode material which is formed of an Si-based alloy and is for use in electricity storage devices wherein lithium ions move during charging and discharging. The negative electrode material which is formed of an Si-based alloy has an Si main phase that is composed of Si and a compound phase that is composed of Si and one or more elements other than Si. The compound phase comprises a phase containing a phase composed of Si and Cr or a phase composed of Si, Cr and Ti. The Si crystallite size in the Si main phase is 30 nm or less, and the crystallite size in the compound phase composed of Si and Cr or in the compound phase composed of Si, Cr and Ti is 40 nm or less. The total content of Cr and Ti is 21.1-40 at.%, and the ratio of Cr to Ti, specifically Cr%/(Cr% + Ti%) is within the range of 0.15-1.00.