Deposition Mode Design of Li2S: Transmitted Orbital Overlap Strategy in Highly Stable Lithium-Sulfur Battery

Serious lithium polysulfides (LiPSs) shuttle effect and slow kinetic process lead to poor cycle performance and low working efficiency of lithium-sulfur battery (Li-S battery), which limits its commercialization. In this paper, a composite frame with transmitted orbital overlap is proposed as the functionalized separator of Li-S battery (MX@WSSe/PP). It consists of WSSe nanosheets and MXenes nanosheets (MX). The experiments and theoretical calculations both show that MX@WSSe/PP can not only inhibit the LiPSs shuttle effect to realize the effective utilization of cathode materials, but also enhance the overall reversibility and reaction kinetics of the device by transforming the 2D deposition mode of Li2S into 3D mode. The transformation of Li2S deposition mode comes from the changed local charge density on MX@WSSe composite surface, which regulates the filling state of electron orbits and affects the orbital overlap between different atoms. This effect can even be transmitted to Li2S molecules far from the surface of MX@WSSe. The capacity decay per cycle of Li-S battery with MX@WSSe/PP is only 0.016% in 1000 cycles at 2 C. Also, a high area capacity of 9.39 mAh cm(-2) is achieved at high sulfur loading (10.2 mg cm(-2)) and low electrolyte/sulfur ratio (7.5 mu L mg(-1)).

Automated summary

In this study, a new functionalized separator for Li-S batteries is proposed, which improves the cycle performance and reaction kinetics by changing the deposition mode and controlling the charge density. Experimental results show that this separator can effectively suppress the shuttle effect of LiPSs and achieve efficient utilization of cathode materials.