Browsing by Author "Jana, PP"
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- ItemThe phase evolution of tetradymite-type bismuth selenide in alkali ion batteries(Elsevier, 2021-08-01) Gillard, C; Djohari, K; Jana, PP; Avdeev, M; Sharma, NTetradymite-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.
- ItemThe structural evolution of tetradymite-type Sb2Te3 in alkali ion batteries(Elsevier, 2021-08-05) Gillard, C; Jana, PP; Avdeev, M; Sharma, NTetradymite-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 © 2021 Published by Elsevier B.V.