Theoretical investigation of two-dimensional phosphorus carbides as promising anode materials for lithium-ion batteries

TL;DR

This study uses first-principles calculations to evaluate 2D phosphorus carbide monolayers as high-capacity, stable anode materials for lithium-ion batteries, showing promising electronic properties and low lithium diffusion barriers.

Contribution

It is the first to investigate 2D phosphorus carbide monolayers as LIB anodes using DFT, revealing their stability, high capacity, and fast lithium diffusion.

Findings

High structural stability of 2D PCx monolayers.

Low lithium diffusion energy barriers (0.18-0.47 eV).

High theoretical specific capacities (1251.7 and 1235.9 mAh g-1).

Abstract

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 PCx, x=2, 5, and 6) monolayers as anode materials for lithium-ion batteries. The 2D PCx systems are predicted to show outstanding structural stability and electronic properties. From the nudge elastic band calculations, the Li atoms show extreme high diffusivities on the PCx 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 mAh g-1, respectively, several times that of graphite anode used in commercial LIBs. These results suggest that both PC5 and PC6 monolayer 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.