Monolayer Be2P3N as a high capacity and high energy density anode material for ultrafast charging Na- and K-ion batteries

Designing high performance electrode materials for the new generation battery with low cost, high specific capacity, high rate capacity, excellent electronic and mechanical properties are highly desirable for the applications of renewable energy. In this work, we have investigated the possibility of using 2D ternary elemental material Be2P3N as anode for Na-and K-ion batteries by using density functional theory. Be2P3N monolayer is expected to have high specific capacity (Na/K: 2574/1716 mAh/g). The predicted energy densities (Na/K: 5055/ 3325 mWh/g) are significantly higher than some precedent 2D analogues. Further, ultra-low ion diffusion barriers are found to be 0.06 and 0.04 eV for Na and K, respectively, indicating high rate capacity. In the Na/K intercalation process, Be2P3N remains metallic which gives rise to the electronic conductivity and battery operating cycle. At high ionic concentrations, the occurrence of reversible phase transition in the substrate has been observed which enhances the specific capacity for K-ion battery. AIMD simulations reveal that the fully Na/K loaded Be2P3N is thermal dynamically stable at 400 K. These intriguing results suggest that the 2D Be2P3N can be a promising anode candidate for Na- and K-ion batteries.