High-Performance Aqueous Calcium Ion Batteries Enabled by Zn Metal Anodes with Stable Ion-Conducting Interphases.

Guo, Weihua; Tian, Fei; Fu, Danchen; Cui, Hao; Song, Huawei; Wang, Chengxin · Nano Lett · 2024

basic_science · Level V

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Abstract

Aqueous calcium ion batteries, promising for energy storage, are still challenged by very limited anode choices. Although a Zn metal anode is popular in aqueous batteries, interface instability due to incessant corrosion and severe Zn dendrites hinders its development. Here, an interphase layer with densely packed nanocrystals of Ca<sub>3</sub>(CO<sub>3</sub>)<sub>2</sub>(OH)<sub>2</sub>·1.5H<sub>2</sub>O and ZnF<sub>2</sub>, and amorphous organic species, is demonstrated for a Zn metal anode with 1 M calcium trifluoromethyl sulfonate aqueous electrolyte. The hybrid interface fully avoids direct Zn-H<sub>2</sub>O contact, maintains fast ion conductivity, and effectively prevents corrosion and dendrite growth. Therefore, the symmetric cell stably lasts for 1600 h at 0.5 mA cm<sup>-2</sup> and 2.5 mAh cm<sup>-2</sup>, far superior to 150 h for the control cell. Furthermore, the device maintains 80% capacity retention after 700 cycles at 1 A g<sup>-1</sup>, outperforming 13% retention after 200 cycles for the control device. This work indicates that interface and interphase engineering is also crucial for aqueous batteries.