Synchrotron X-ray Spectroscopic Investigations of In-Situ-Formed Alloy Anodes for Magnesium Batteries.

Xu, Xin; Ye, Chao; Chao, Dongliang; Chen, Biao; Li, Huan; Tang, Cheng; Zhong, Xiongwei; Qiao, Shi-Zhang · Adv Mater · 2022

basic_science · Level V

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Abstract

Magnesium batteries present high volumetric energy density and dendrite-free deposition of Mg, drawing wide attention in energy-storage devices. However, their further development remains stagnated due to relevant interfacial issues between the Mg anode and the electrolyte and sluggish solid-state diffusion kinetics of Mg<sup>2+</sup> ions. Herein, an in situ conversion chemistry to construct a nanostructured Bi anode from bismuth selenide driven by Li<sup>+</sup> is proposed. Through the combination of operando synchrotron X-ray diffraction, ex situ synchrotron X-ray absorption spectroscopy, and comprehensive electrochemical tests, it is demonstrated that the nanosize of the in-situ-formed Bi crystals contributes to the fast Mg<sup>2+</sup> diffusion kinetics and highly efficient Mg-Bi alloingy/de-alloying. The resultant Bi anodes exhibit superior long-term cycling stability with over 600 cycles under a high current density of 1.0 A g<sup>-1</sup> . This work provides a new approach to construct alloy anode and paves the way for exploring novel electrode materials for magnesium batteries.