Anisotropic electrene T'-Ca 2 P with electron gas magnetic coupling as anode material for Na/K ion batteries.

There is an urgent need for high-performance rechargeable electrical storage devices as a supplement or a substitution for lithium ion batteries (LIBs) due to the shortage of lithium in nature. Herein we propose a stable 2D electrene T'-Ca 2 P as an anode material for Na/K ion batteries developed using first principles calculations. Our calculated results show that the T'-Ca 2 P monolayer is an antiferromagnetic semiconducting electrene with a spin-polarized electron gas. It exhibits suitable adsorption for both Na and K atoms, and its anisotropic migration energy barriers are 0.050/0.101 eV and 0.037/0.091 eV in the b/a direction, respectively. The theoretical capacities for Na and K are both 482 MA h g -1 , whereas the average working voltage platforms are 0.171-0.226 V and 0.013-0.267 V, respectively. All the results reveal that the T'-Ca 2 P monolayer has promising prospects for application as an anode material for Na/K ion batteries.