Monolayer PC₅/PC₆: promising anode materials for lithium-ion batteries

Employing two-dimensional (2D) materials as anodes for lithium-ion batteries (LIBs) is believed to be an effective approach to meet the growing demands of high-capacity next-generation LIBs. In this work, the first-principles density functional theory (DFT) calculations are employed to evaluate the potential application of two-dimensional phosphorus carbide (2D PC_x, x = 2, 5, and 6) monolayers as anode materials for lithium-ion batteries. The 2D PC_x systems are predicted to show outstanding structural stability and electronic properties. From the nudged elastic band calculations, the single Li atom shows extreme high diffusivities on the PC_x monolayer with low energy barriers of 0.18 eV for PC₂, 0.47 eV for PC₅, and 0.44 eV for PC₆. We further demonstrate that the theoretical specific capacity of monolayer PC₅ and PC₆ can reach up to 1251.7 and 1235.9 mA h g^-1, respectively, several times that of a graphite anode used in commercial LIBs. These results suggest that both PC₅ and PC₆ monolayers are promising anode materials for LIBs. Our work opens a new avenue to explore novel 2D materials in energy applications, where phosphorus carbides could be used as high-performance anode in LIBs.