Post-lithium-ion batteries: characterization of phosphorous and tin for potassium-ion anodes

Abstract

Herein we present a computational study on the characteristics of two potassium-ion based anode systems for energy storage applications. Different phases of K–Sn and K–P systems have been examined, and those that can be formed in a secondary battery are further characterized. The characterization includes mechanical properties, such as bulk modulus, and electronic properties, such as band structure and chemical shielding. The voltage profile of the anode during charging, the diffusion barrier of ions in fully charged phases, and X-ray diffraction were investigated using a density functional theory approach. The density of states and band-gap of the thermodynamically feasible systems are calculated. The simulation results suggest that both systems perform in a range that is acceptable for use in energy storage applications. It is noted that, while a higher capacity can be achieved for the K–P system, K–Sn would lead to a better discharge rate. This suggests that a composite of these two systems can have real applications. Comparing mechanical properties with the evolution of total charge from the atoms gives insight into the physics underlying these mechanical properties. The simulation results may help the experimentalists better characterize the electrochemistry of the charge and discharge processes in K–Sn and K–P batteries.