The phase evolution of tetradymite-type bismuth selenide in alkali ion batteries

Abstract

Tetradymite-type Bi2Se3 is synthesised via a solid-state method, and its phase evolution in Li, Na and K half-cells is experimentally investigated. Ex-situ X-ray diffraction data is analysed with the Rietveld method, indicating intercalation, conversion and alloying reactions for all systems. Direct evidence of alloying is observed in the cases of the Li and Na systems while alloying is inferred for the K system. In addition, a preliminary study of the performance of Bi2Se3 as an electrode material for rechargeable Li, Na and K-half cells is undertaken. High initial capacities of 560, 680 and 1000 mAh/g for Li, Na and K respectively are observed. However, capacity fade is severe in all cases, with 10th cycle capacity decreases of 68%, 79% and 90% respectively. This poor cyclability is likely attributable to the large volume changes that accompany the conversion and alloying reactions. Finally, the magnetic properties of the resultant intercalated materials are investigated. Li intercalation induces a divergence between zero-field cooled and field cooled curves below 150 ​K, whereas Na and K intercalation do not have significant effects on the observed magnetic properties. Crown Copyright © 2021 Published by Elsevier Inc.