Design Principles of Mediation Layer for Current Collectors Toward High‐Performance Anode‐Free Potassium‐Metal Batteries: A Case Study of Cu<sub>6</sub>Sn<sub>5</sub> on Copper
Naiqing Ren, Lifeng Wang, Xiaoying Li, Kuo Cao, Zixu He, Yu Shao, Jingchao Xiao, Yiran Zhu, Bicai Pan, Shuhong Jiao, Chunhua Chen
Abstract
Abstract Anode‐free potassium (K) metal batteries are promising candidates in high‐energy‐density batteries. Nevertheless, the notorious potassium dendrite growth and poor K plating/stripping efficiency originating from the potassiophobicity of conventional Cu current collectors impede their practical applications. Herein, by means of systematically multi‐scale theoretical simulations, the correlations among K deposition morphology, nucleation sites, and potassiophilicity of mediation layers are well illuminated from thermodynamics and dynamics perspectives. As a proof of concept, a potassiophilic alloy Cu 6 Sn 5 layer is constructed on commercial Cu foils via a facile electroless plating approach. The designed Cu 6 Sn 5 @Cu can guide the homogeneous distribution of K + flux and regulate the electronic field, promoting uniform K + plating and stripping. Meanwhile, a KF‐rich solid electrolyte interphase (SEI) layer with high mechanical strength is electrochemically induced and formed, facilitating the transport of K + through SEI and enhancing the stability of SEI. Consequently, Cu 6 Sn 5 @Cu delivers great performance with durable stability of up to 600 h (1 mA cm −2 and 1 mAh cm −2 ) in no‐reservoir half‐cells. Benefiting from the unique mediation layer design, a novel anode‐free K‐metal full‐cell prototype demonstrates ameliorative cyclic stability. This work advances a fundamental understanding and establishes the bridge between the potassium deposition morphology and mediation layer properties for anode‐free potassium‐metal batteries.