Multistage Li Insertion and Extraction Relaxation Analysis of γ-Fe₂O₃

Abstract

We inserted Li into or extracted Li from Li-inserted γ-Fe₂O₃, and analyzed the structure at relaxation time. For multi-stage Li insertion sample, it was indicated that Fe moved from 8a site to 16c site during Li insertion process and Fe moved from 16c site to 8a site at relaxation process after the Li insertion, and it was suggested that Li is inserted at 8a site with Li insertion process and Li moves from 8a site to 16c site after the Li insertion. For extraction sample, it was indicated that Fe moved from 16c site to 8a site during Li extraction process and it was suggested that Li is extracted from 8a site and Fe at 16c site moves into 8a site. It was considered that Li prefer 8a site to occupy kinetically and prefer 16c site thermodynamically, and that 8a site take a role as a diffusion path for both Li insertion and Li extraction. From the first principle calculation, 16c site preference to 8a site of Li was indicated.