The structural evolution of tetradymite-type Sb2Te3 in alkali ion batteries

Tetradymite-type Sb2Te3 is synthesised via a solid-state method, and its electrochemical phase evolution in Li, Na and K half-cells is experimentally investigated. Ex-situ X-ray diffraction data is analysed with the Rietveld method, revealing the occurrence of conversion reactions for all systems. Direct evidence of alloying and intercalation reactions is observed in the case of the Li system, while alloying is inferred for the K and Na systems. For the first time, Li intercalated Sb2Te3 is synthesised and a preliminary investigation of its magnetic properties is undertaken. Li intercalation does not significantly influence the magnetic phase transition temperature and does not appear to induce superconductivity. In addition, a preliminary study of the performance of Sb2Te3 as an electrode material for rechargeable Li, Na and K-half cells is undertaken. High initial capacities of 588, 521 and 906 mAh/g for Li, Na and K cells respectively are observed. However, capacity fade is rapid in all cases, with second discharge capacities dropping to 396, 173 and 98 mAh/g. This poor cyclability is generally associated with the large volume changes and irreversibilities associated with the conversion and alloying reactions. The capacities continue to decrease during extended cycling, with tenth cycle discharge capacities of 195, 26 and 24 mAh/g for Li, Na and K half cells respectively. Crown Copyright (C) 2021 Published by Elsevier B.V. All rights reserved.

Automated summary

Tetradymite-type Sb2Te3 is synthesized using a solid-state method and its electrochemical behavior in Li, Na, and K half-cells is investigated. Conversion and alloying reactions are observed in all systems, with direct evidence of alloying and intercalation reactions seen in Li system. Preliminary investigation of the magnetic properties of Li-intercalated Sb2Te3 shows no significant influence on the magnetic phase transition temperature or induction of superconductivity. High initial capacities are observed for all systems, but rapid capacity fade is noted due to large volume changes and irreversibilities associated with the conversion and alloying reactions.