Recent Progress of Potassium Metal Anodes: How to Regulate the Growth of Dendrite

Abstract

Potassium- (K-) based batteries with K metal anodes have been regarded as a substitute for lithium- (Li-) and sodium- (Na-) based batteries. In this review, motivations for K metal anodes with various advantages over Li and Na metals are presented at the beginning. Nevertheless, the practical applications of K metal anodes are still impeded by various challenges originating from their highly reactive nature. Then, major challenges of K metal are introduced in comparison with those of Li and Na metals, including unstable SEI, dendrite growth, low melting point, and gas generation. These issues become more severe in K metal due to its different physical and chemical properties compared with Li and Na metals. Consequently, this leads to varying electrochemical behaviors. In particular, the mechanism of K dendrite growths is different from that of Li and Na. Subsequently, approaches with an emphasis on the suppression of dendrites are described, falling into two categories: direct and indirect engineering on electrodes. Direct engineering is K metallic electrode designs by utilizing a host framework, alloy electrode, and interface modification. Notably, the most crucial aspect considered in direct engineering is the potassiophilicity of the host and interface, which contributes to the uniform deposition of K. The section on indirect engineering addresses the suppression of dendrite growth through separators and liquid/solid electrolytes. Finally, future perspectives and research directions toward the suppression of K dendrites are provided.