The effect of biaxial strain on the electronic properties, quantum capacitance and diffusion of Li adsorption on Sc2CO2 MXene

Abstract

Searching for high-performance electrode materials is an urgent need for lithium-ion batteries (LIBs) and supercapacitors. The electronic properties, quantum capacitance and diffusion of Li adsorption on Sc2CO2 under biaxial strain are investigated by density functional theory. Twelve adsorption sites are considered. The most stable adsorption site is confirmed through adsorption energy. The adsorption of Li makes Sc2CO2-Li monolayer become the magnetic semiconductor, with the maximum bandgap of 1.84 eV at −2 % strain and 0.76 eV at +4 % strain for spin-up and spin-down states, respectively. The maximum theoretical capacity of Sc2CO2 monolayer is 190.26 mAhg−1. The most appropriate diffusion path for Li atom is confirmed by analyzing diffusion barriers and Sc2CO2-Li monolayer under −4 % strain is more suitable as an anode material for LIBs because of the minimum open circuit voltage (OCV) and diffusion barrier. The coexistence of biaxial strain and Li adsorption doesn't change the cathode electrode type of Sc2CO2 monolayer. Charge transfer in Sc2CO2-Li monolayer under strain is further analyzed.