Highly reversible formation and decomposition of S–S dimers driven by the migration of metal Cr in layered NaCr2/3Ti1/3S2

DOI number:10.1038/s41467-019-12310-6

Journal:Nature Communications

Key Words:X-RAY-ABSORPTION；POSITIVE ELECTRODE；CRYSTAL-STRUCTURE；VANADIUM SULFIDE；SULFUR；CHEMISTRY；CATHODES；SPECTROSCOPY；CHALLENGES；MOSSBAUER

Abstract:The use of anion redox reactions is gaining interest for increasing rechargeable capacities in alkaline ion batteries. Although anion redox coupling of S2- and (S-2)(2-) through dimerization of S-S in sulfides have been studied and reported, an anion redox process through electron hole formation has not been investigated to the best of our knowledge. Here, we report an O3-NaCr2/3Ti1/3S2 cathode that delivers a high reversible capacity of similar to 186 mAh g(-1) (0.95 Na) based on the cation and anion redox process. Various charge compensation mechanisms of the sulfur anionic redox process in layered NaCr2/3Ti1/3S2, which occur through the formation of disulfide-like species, the precipitation of elemental sulfur, S-S dimerization, and especially through the formation of electron holes, are investigated. Direct structural evidence for formation of electron holes and (S2)(n-) species with shortened S-S distances is obtained. These results provide valuable information for the development of materials based on the anionic redox reaction.

First Author:Tian Wang

Co-author:Guo-Xi Ren, Ji-Li Yue, Yi-Fei Mo, Xi-Qian Yu, Ming-Hui Cao, Zulipiya Shadike

Correspondence Author:Pan Liu,Xiaosong Liu,Zheng-Wen Fu

Document Code:4458

Volume:10

ISSN No.:2041-1723

Translation or Not:no

Date of Publication:2019-10-01

Links to published journals:https://www.nature.com/articles/s41467-019-12310-6