Two-Dimensional Transition Metal Dichalcogenides as the Promising Anodes for Potassium Ion Battery from First-principles Prediction
Two-dimensional (2D) materials are expected to be utilized as the electrodes for alkali metal ion batteries due to their exceptional properties, but the larger size of K ion has been supposed to induce structural collapses and low charge-discharge efficiency. In this work, we propose the transition metal dichalcogenides (TMDs) materials as the anode electrodes for potassium ion batteries (PIBs). The K ion can be stably adsorbed on most of the TMDs materials with the strong adsorption energies, and the structural phase transition from 2H phase to 1T phase can further enhance the K adsorption. It is surprising that, the diffusion barriers for K ion on TMDs monolayers are low enough (less than 0.05 eV) to allow K ions freely migrating. Among the TMDs materials that we consider here, both VS2 and TiS2 exhibit extraordinary properties with good electronic conductivity, fast K diffusion, optimal open circuit voltage and high theoretical K storage capacity, which are the promising anode materials for K ion batteries.