Transition metals doped borophene-graphene heterostructure for robust polysulfide anchoring: A first principle study

Abstract

Borophene shows great potential to be applied in lithium-sulfur (Li-S) battery as an inhibitor of polysulfides shuttling due to its two-dimensional stable structure and high electronic conductivity. In order to evaluate polysulfides anchoring capability of different configurations of borophenes, density functional theory (DFT) has been employed to calculate the adsorption energies of polysulfides on borophenes of different configurations. The DFT results show that the perfect puckered borophene B0 gives better adsorption performance towards the polysulfides than three defective borophenes (B1, B2 and B3). The DFT calculations also reveal that deformations of borophenes are triggered by the polysulfides adsorption, but the deformation of borophenes can be restrained by forming 2D heterogeneous structure with graphene (B0/G) without compromising the polysulfide immobilization capability. B0/G shows the strongest anchoring capability among the Bx/G composites. Furthermore, to strengthen the adsorption of polysulfides on B0/G, the B0 layer is doped with different transition metals (Ti, Mn, Fe, Co, Ni, Cu), and the adsorption energies increase with the increasing reducibility of the doped transition metal atoms. Ti-doped B0/G shows the best performance for suppressing the polysulfides shuttle effect. This work demonstrated that the graphene compositing and transitional metal doping have large impacts on the performance of the borophene for polysulfides anchoring.