Can P3S and C3S Monolayers be Used as Anode Materials in Metal-Ion Batteries? An Answer from First-Principles Study

With the urgent need for efficient energy storage devices, enormous attention has been paid to researching and developing promising anode materials for metal-ion batteries. Through density functional study, we have successfully predicted the electrochemical performance of the P3S and C3S monolayers for the first time, which could be used in alkali metal (Li, Na, and K)-ion batteries. Our study examines the pristine monolayers' energetical, dynamical, and thermal stability. The electronic structures of the pristine nanosheets exhibit wide-gap semiconductors. After single metalation on the monolayers, the composite systems become metallic. Charge density difference (CDD) analysis indicates that charge transfer occurs from the alkali metal atoms to the P3S and C3S monolayers, and Bader charge analysis quantifies the amount of charge transfer. We have analyzed how readily a single adatom diffuses within the 2D structures. One example is the diffusion of K on C3S, which has a low barrier value of 0.06 eV and seems practically barrierless. Furthermore, our predicted composite systems report considerable theoretical storage capacity (C); for example, hexalayer K-adsorbed C3S shows a storage capacity of 1182.79 mA h g−1. The estimated open-circuit voltage (OCV) values imply that the C3S monolayer is promising anode material for Li-, Na-, and K-ion batteries, while the P3S monolayer is suitable as cathode material for Li-, Na-, and K-ion batteries.