Search for potential K ion battery cathodes by first principles

An important challenge facing K-ion batteries lies in exploring earth-abundant and safe cathode materials that can provide high capacity with high migration rate of K ions. Here, we propose a simple and efficient method for searching potential K cathode materials with first principles calculations. Our screening is based on combinations of weight capacity, K ion occupation ratio, volume change per K, and valence limit. With this screening method we predicted a series of potential K ions cathodes with favorable electrochemical performance, such as K2VPO4CO3-like structures with 1D diffusion channels, 3D channel structures K2CoSiO4, layered materials KCoO2, KCrO2, KVF4 and K5V3F14, and others. These potential cathodes have small volume changes, suitable voltage, and high capacity, with small diffusion barriers. They may be useful in K-ion batteries with high energy density and rate performance.