Bimetallic Rechargeable Al/Zn Hybrid Aqueous Batteries Based on Al-Zn Alloys with Composite Electrolytes.

Yang, Xiaohu; Zhang, Chen; Chai, Luning; Zhang, Wenming; Li, Zhanyu · Adv Mater · 2022

basic_science · Level V

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Abstract

Aluminum is abundant and exhibits a high theoretical capacity and volumetric energy density. Additionally, the high safety of aqueous aluminum-ion batteries makes them strong candidates for large-scale energystorage systems. However, the frequent collapse of the cathode material and passive oxide film results in the difficult development of aqueous aluminum-ion batteries. This work provides a novel battery system, namely, Al-Zn/Al(OTF)<sub>3</sub> +HOTF+Zn(OTF)<sub>2</sub> /Al<sub>x</sub> Zn<sub>y</sub> MnO<sub>2</sub> ·nH<sub>2</sub> O, with a mixed electrolyte. The cathode applies MnO topology transformation to ensure that the cathode forms Al<sub>x</sub> MnO<sub>2</sub> ·nH<sub>2</sub> O. Topology transformation alters the structure of the cathode material so that Zn<sup>2+</sup> can be intercalated into the Al<sub>x</sub> MnO<sub>2</sub> ·nH<sub>2</sub> O spinel structure to provide support for the material structure. Regarding the anode, Zn<sup>2+</sup> in the electrolyte is deposited onto Al of the anode to produce a regional Al-Zn alloy. Zn<sup>2+</sup> is reduced to Zn metal during discharging, which adds a platform for secondary discharge beneficial for battery capacity enhancement. This system can provide a 1.6 V discharge platform, while the first cycle discharge can reach 554 mAh g<sup>-1</sup> , thereby maintaining a high capacity of 313 mAh g<sup>-1</sup> after 100 cycles. This study provides a new idea for the further development of aqueous aluminum-ion batteries (AAIBs).