Effects of Si, B doping on PC3 monolayer as anode for Na-ion batteries.

Two-dimensional phosphorus carbides are predicted to be promising anode materials for Na-ion batteries due to their high theoretical capacity, low diffusion barrier, low volume expansion rate and excellent electronic conductivity. However, previous theoretical calculations show that most phosphorus carbides have weak adsorption for Na atoms, which may lead to the fact that Na atoms are prone to aggregate to form Na dendrites during the charging and discharging process. Here, the effects of Si and B doping on the structural stability, and the adsorption and diffusion behaviors of Na atom of PC 3 were investigated using first-principles calculations. The results show that single Si and B atom doping has more negative formation energy at the P site. Si and B doping enhances the adsorption properties of PC 3 for Na atom, and the maximum adsorption energy of Na on the Si-doped system is decreased to −1.87 eV. B-doped PC 3 monolayer has more Na atom adsorption sites than the undoped ones. Therefore, it can be concluded that Si and B doping is a feasible way to improve the weak Na adsorption in the PC 3 monolayer. This work provides guidance for improving the electrochemical performance of phosphorus carbides. • The adsorption and diffusion behavior of Na atom on Si and B-doped PC 3 monolayer is considered. • The adsorption properties of Si-doped PC 3 for Na atom is more significantly enhanced compared to B-doped PC 3. • The diffusion barrier of Na atom on B-doped PC 3 lower than Si-doped PC 3. [ABSTRACT FROM AUTHOR]