Samarium Ion-induced Interfacial Regulation to Construct High-performance Anodes for Aqueous Zinc Metal Batteries

Zinc metal batteries (ZMBs) are attracting wide attention due to their high-safety, low-cost and environment-friendly. Nevertheless, the loose deposites and dendrites on Zn anodes significantly hinders the cycling life of ZMBs. Herein, we propose the incorporation of samarium chloride (SmCl3) additives into the aqueous electrolyte to construct ZMBs. The SmCl3 additives diminishes the thickness of the electric double layer (EDL) on the Zn anodes to lessen the repulsive forces between Zn deposits and thus promote the dense deposition of metallic Zn. Furthermore, the Sm3+ ions not only are preferentially adsorped at the active sites (i. e. the protrusions of Zn anodes) to effectively suppresses the formation of Zn dendrites, but also optimize the Zn2+ ions diffusion rate and inhibit the existence of highly active water molecules on the surface of Zn anodes to reduce the side reactions. Hence, the Zn||Zn symmetric batteries containing SmCl3 additives stably operate for 2100 h at 2 mA cm-2, and even shows the stable discharge/charge curves for 100 h under high current of 50 mA cm-2. The HNaV6O16·4H2O (HNVO)-based ZMBs with SmCl3 additives achieve the high initial discharge capacity (257 mAh g-1) and remarkable cycling life (1000 cycles) at 1 A g-1and also show the good capacity retention of 96.39% after 36 h resting. When combined with polyaniline (PANI) cathodes, the corresponding SmCl3-based battery also displays good cycling performance (1000 cycles at 5 A g-1). This work highlight the multi-functions of the rare earth metal-based additives in aqueous ZMBs.