Flexible borophosphene monolayer: A potential Dirac anode for high-performance non-lithium ion batteries

Non-lithium ion batteries (NLIBs) have received great interest in the next generation renewable energy storage due to their intrinsic safety and low cost; nonetheless, searching for a high-performance anode still remains a great challenge. Herein, using first principles calculations, we have evaluated the feasibility of recently developed borophosphene (B2P2) as a Dirac anode of NLIBs. Our results demonstrate that Na, K, Ca could form stable adsorption on the B2P2 along with the adsorption energy of −1.27 – −0.36 eV. The B2P2 exhibits a semimetal characteristic, ensuing excellent conductivity for the rapid electron transport. Moreover, diffusion barriers of Na, K and Ca are 0.10, 0.07 and 0.33 eV, respectively, indicative of high ion mobility. The specific capacities in Na, K and Ca-ion batteries are up to 1282.34, 854.89 and 1282.34 mA h/g, which are significantly larger than that of commercial electrode. Furthermore, B2P2 could withstand large ultimate strain (>16%) and shows a good mechanical flexibility, which are of great benefit to accommodate its volumetric expansion and contraction during cycling. Given its high electrical conductivity, large adsorption energy, high specific capacity, fast ion diffusion and excellent mechanical property, B2P2 is a potential anode to achieve advanced Na, K and Ca-ion batteries.