Half-Metallic PN2 Monolayer as High-performance Anode Material for Metal Ion (Li, Na and K) Batteries: A First-Principles Study

Searching for an appropriate anode material with desirable electrochemical performance is crucial in the development of metal ion batteries. In this work, based on the extensive first-principles computations, we have systemically assessed the potential of an emerging PN2 monolayer as an anode material for lithium (LIBs), sodium (NIBs) and potassium (KIBs) ion batteries. The PN(2 )monolayer possesses excellent thermal, dynamical and mechanical stability, and it is half-metallic with two energy bands crossing over the Fermi level in the spin-down channel. Moreover, the diffusion barriers of Li, Na and K atoms on the PN2 are as low as 0.11, 0.09 and 0.05 eV, showing a high ionic mobility. The storage capacities of PN2 anode are predicted to be 2725.53, 1413.24, and 908.51 mAh/g for LIBs, NIBs and KIBs. Importantly, the PN2 anode exhibits strong affinity towards metal atoms and negligible structural distortion during the whole intercalation process, which is of importance to improve the cyclability and prevent the metallic dendrite formation. All the encouraging findings demonstrate that the PN(2)anode holds great promise in the high-performance metal ion battery application.