Boron phosphide (BP) biphenylene and graphenylene networks as anode and anchoring materials for Li/Na–ion and Li/Na–S batteries

Using first-principles density functional theory (DFT) calculations, we evaluate the suitability of BP-biphenylene (b-BP) and BP-graphenylene (g-BP) monolayers for Li+/Na+-ion and Li/Na-S batteries. In our evaluations, we consider factors such as the adsorption energy (Eads) of b-BP and g-BP with adsorbed Li/Na adatoms, Li/Na polysulfides (Li/NaPSs) and S8 clusters as well as the storage capacity and diffusion energy barrier (Ebar) of Li+/Na+-ion on these surfaces. Our results indicate significantly higher Li+/Na+-ion storage capacities for b-BP at 700 mAh/g and g-BP at 550 mAh/g compared to typical graphite anode (372 mAh/g) and other carbon material (450 mAh/g). The Ebar values for Li+/Na+-ion were found to be 0.84/0.63 eV and 0.65/0.37 eV for b-BP and g-BP monolayers, respectively. The obtained Ebar values fall within the acceptable range of theoretically reported value for commercial TiO2 (0.4–1.0 eV) anode. The estimated open-circuit voltage (OCV) values fall within the acceptable range of 0.1–1.0 V for anode materials. Additionally, the Eads values of Li/NaPSs and S8 clusters on b-BP and g-BP surfaces are up to -2.80/-2.91 and -3.00/-3.13 eV, respectively, effectively preventing the unintended decomposition of Li/NaPSs. These findings highlight the potential of both b-BP and g-BP monolayers as promising anode materials for Li/Na-ion batteries as well as anchoring materials for Li/Na-S batteries, mitigating the shuttle effect.