Rational Exploration of Conversion-Alloying Reaction Based Anodes for High-Performance K-Ion Batteries

The difficulties encountered in finding proper anode materials with high capacities and rate capabilities are a prime obstacle hindering the realization of high-performance K-ion batteries (KIBs). Electrodes undergoing reversible conversion-alloying reactions with K-ions could offer much higher capacities than traditional intercalation-based anodes, while the available candidates remain rather limited. Herein, high-performance metal chalcogenides (MCs) are explored through descriptor-assisted theoretical screening. Among potential candidates for metal constituents of MCs, thermodynamically stable Bi and Sb are chosen based on density functional theory calculations: while Sb possesses a significantly higher theoretical capacity than Bi, Bi presents better cyclic stability and lower electrochemical potentials than Sb. In addition, chalcogens with high atomic numbers favor K-diffusion kinetics in terms of diffusion barrier and K vacancy formation energy. Taking into account the relative merits and weaknesses, layer-structured SbBiTe3 is identified as the choice anode. Even without elaborate design of electrode morphologies using a complicated fabrication method, the SbBiTe3/graphite anode prepared by a simple and scalable ball-milling strategy delivers a remarkable capacity of 202 mAhg-1 after prolonged 1000 cycles at 80 mAg-1 with Coulombic efficiencies consistently higher than 99%, signifying its intrinsically excellent electrochemical performance compared to other electrode materials. The unique approach developed here uncovers new possibilities in search of advanced anodes and sheds light on the development of high-performance KIBs based on theoretical exploration.