A Reversible Rocksalt to Amorphous Phase Transition Involving Anion Redox

Atsushi Sakuda, Koji Ohara, Tomoya Kawaguchi, Katsutoshi Fukuda, Koji Nakanishi, Hajime Arai, Yoshiharu Uchimoto, Toshiaki Ohta, Eiichiro Matsubara, Zempachi Ogumi, Kentaro Kuratani, Hironori Kobayashi, Masahiro Shikano, Tomonari Takeuchi, Hikari Sakaebe

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

The charge-discharge capacity of lithium secondary batteries is dependent on how many lithium ions can be reversibly extracted from (charge) and inserted into (discharge) the electrode active materials. In contrast, large structural changes during charging/discharging are unavoidable for electrode materials with large capacities, and thus there is great demand for developing materials with reversible structures. Herein, we demonstrate a reversible rocksalt to amorphous phase transition involving anion redox in a Li2TiS3 electrode active material with NaCl-type structure. We revealed that the lithium extraction during charging involves a change in site of the sulfur atom and the formation of S−S disulfide bonds, leading to a decrease in the crystallinity. Our results show great promise for the development of long-life lithium insertion/extraction materials, because the structural change clarified here is somewhat similar to that of optical phase-change materials used in DVD-RW discs, which exhibit excellent reversibility of the transition between crystalline and amorphous phase.

Original languageEnglish
Article number15086
JournalScientific reports
Volume8
Issue number1
DOIs
Publication statusPublished - 2018 Dec 1

ASJC Scopus subject areas

  • General

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