Functionalized Mo2B2 MBenes: Promising anchoring and electrocatalysis materials for Lithium-Sulfur battery

Abstract

Applications of Li-S batteries are primarily hindered by shuttling effect, poor electronic conductivity of sulfur and inactive decomposition of low-order lithium polysulfide (LiPS). To solve these problems, the anchoring and electrocatalysis properties of two-dimensional transition metal boride (MBene) have been extensively studied to provide general design principles for enhanced electrochemical performance in Li-S batteries. Our results show that direct application of bare Mo2B2 MBene in Li-S battery gives rise to the decomposition of high-order LiPSs, which originates from the excessively strong binding strength between S atoms and surface Mo atoms. Then, we highlight that surface functionalization on Mo2B2 MBene possesses suitable anchoring performance to suppress the shuttling effect. Meanwhile, owing to the excellent electronic conductivity even after the adsorption of LiPS, the functionalized MBenes effectively stimulate the redox electrochemistry in Li-S battery. Finally, accompanied with omnidirectional fast diffusion of Li atom, the functionalized MBene exhibits superior electrocatalysis activity for Li2S decomposition with ultra-low diffusion (0.191 eV) and decomposition (0.441 eV) barriers, improving the capability and coulombic efficiency of Li-S batteries. Our findings pioneer the application of MBenes as anchoring and electrocatalysis materials for Li-S batteries and provide a developed insight on the design of high-performance Li-S battery cathodes.