Preparation of Low Surface Area Si-Alloy Anodes for Li-Ion Cells by Ball Milling

Abstract

A new and simple 2-step milling technique is utilized to produce Si–Ti–N alloys with significantly reduced surface area compared to conventional ball milling, while still attaining a full amorphous active Si phase. Surface area reductions of up to 100% were obtained by this method. Surprisingly, this did not result in significant differences in cycling stability compared to conventionally ball milled high surface area alloy materials. This is likely because cycling caused severe fracturing of the alloy surfaces, resulting in a high surface area, regardless of the initial surface area of the alloy. This suggests that, unlike other anode materials such as graphite, reducing the initial surface area of Si alloys does not translate into reduced electrolyte reactivity.