High areal loading and long-life cycle stability of lithium-sulfur batteries achieved by a dual-function ZnS-modified separator

Abstract Stabilizing the lithium anode while inhibiting the shuttle effect to achieve stable circulation under high sulfur loading is an inevitable problem for the commercialization of lithium-sulfur batteries. A low cost of raw materials and a simple synthesis are also important prerequisites for product commercialization. In this paper, zinc sulfide (ZnS) nanoparticles embedded in nitrogen-doped 3D-carbon nanosheets (NCNS) are proposed as modified separator materials. During high-temperature carbonization of the carbon materials, a zinc sulphide phase transition occurs, resulting in an anion vacancy (S2-) and an unsaturated Zn centre. While maintaining catalytic activity, the unsaturated Zn centre in ZnS acts as a Lewis acid to form a coordinate bond with the polysulfide. Furthermore, a uniform distribution of N heteroatoms can effectively regulate Li+ flux through the separator, thereby achieving a stable cycle for the lithium anode. A cell with the ZnS/NCNS-modified separator can achieve a stable cycle at 0.5 C and superior electrochemical performance even with an areal sulfur loading of 6 mg cm−2. An excellent reduction in self-discharge was also confirmed by a 4% capacity attenuation after resting for 4 days. This work provides new insight on the design and preparation of novel separators for highly stable Li–S batteries via a “green” and cost-effective approach.