Volume 57, Issue 48 pp. 15743-15748
Communication

Efficient Nanostructuring of Silicon by Electrochemical Alloying/Dealloying in Molten Salts for Improved Lithium Storage

Yating Yuan

Yating Yuan

Department Hubei Key Laboratory of Electrochemical Power Sources, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072 P. R. China

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Dr. Wei Xiao

Dr. Wei Xiao

Department Hubei Key Laboratory of Electrochemical Power Sources, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072 P. R. China

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Dr. Zhiyong Wang

Dr. Zhiyong Wang

Department Hubei Key Laboratory of Electrochemical Power Sources, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072 P. R. China

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Prof. Derek J. Fray

Prof. Derek J. Fray

Department of Material Sciences and Metallurgy, University of Cambridge, Cambridge, CB3 0FS UK

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Prof. Xianbo Jin

Corresponding Author

Prof. Xianbo Jin

Department Hubei Key Laboratory of Electrochemical Power Sources, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072 P. R. China

Department of Material Sciences and Metallurgy, University of Cambridge, Cambridge, CB3 0FS UK

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First published: 10 October 2018
Citations: 51

Graphical Abstract

Bulk silicon can be nanostructured in a comparatively low-energy and environmentally benign approach of electrochemical Mg alloying/dealloying in molten salts at moderate temperatures. For lithium storage, the nanostructured Si exhibits a combination of high initial Coulombic efficiency, high specific capacity, and long cycling stability.

Abstract

Application of nanostructured silicon (nSi) is significantly retarded by challenges in the production of affordable nSi. We herein report a high-yield (ca. 100 %) and low-energy (2 kWh Kg-nSi−1) nanostructuring of industrial microsized silicon (mSi) through a closed-loop electrochemical Mg alloying/dealloying in molten MgCl2/NaCl/KCl at 773 K. The resulting nSi unexpectedly shows a salt-unwetted character, allowing an automatic separation from the melts. Thus water washing and accompanying oxidation of the nSi can be avoided. The final product has a nanoporous structure and comprises Si nanorods (ca. 30 nm in diameter) with an ultrathin oxide coating. It can be used for Li storage giving a combination of high initial coulombic efficiency, high specific capacity, and long cycling stability. This nanostructuring process consumes very few chemicals except for the mSi and produces almost zero waste.

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