Bensch, Wolfgang, Ophey, Jannes, Hain, Holger, Gesswein, Holger, Chen, Di, Mönig, Reiner, Gruber, Patric A. and Indris, Sylvio (2012) Chemical and electrochemical insertion of Li into the spinel structure of CuCr2Se4: ex situ and in situ observations by X-ray diffraction and scanning electron microscopy. Physical Chemistry Chemical Physics, 14 (20). p. 7509. DOI 10.1039/c2cp00064d.

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Abstract

The chemical and electrochemical insertion of lithium into the spinel structure of CuCr2Se4 was studied and the chemical reaction pathway was followed by ex situ X-ray diffraction on samples with different Li contents. The electrochemical reaction was investigated by in situ X-ray diffraction and in situ scanning electron microscopy. In the early steps of chemical intercalation, two phases with a different Li content coexist and Cu is extruded from the host material. After 4 days of Li intercalation, a conversion reaction is observed. The overall Li uptake is 8 Li ions per formula unit. The structural behaviour of the two intercalated phases at the early stages of intercalation is totally different. For one phase a strong expansion of the a-axis is observed while for the other phase it is only slightly affected by Li uptake. A three-step mechanism was found consisting of reduction of Se− followed by a Cu–Li exchange and finally a complete reduction of Cr3+ to the metallic state accompanied by the formation of Li2Se. The discharge capacity of the first cycle amounts to 530 mAh g−1 and drops to about 380 mAh g−1 in the fifth cycle. In in situ SEM images the occurrence of Cu whiskers that partially grow out of the crystallites can be observed.

Document Type:	Article
Research affiliation:	Kiel University > Kiel Marine Science OceanRep > The Future Ocean - Cluster of Excellence Kiel University
Refereed:	Yes
Open Access Journal?:	No
Publisher:	Nature Publishing Group
Projects:	Future Ocean
Date Deposited:	12 Jun 2018 10:24
Last Modified:	04 Apr 2019 08:55
URI:	https://oceanrep.geomar.de/id/eprint/43332

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