Bimetallic ZnSe-SnSe2 heterostructure functionalized separator for high-rate Li-S battery

Abstract

The commercialization of lithium-sulfur (Li-S) batteries is significantly hampered by challenges such as rapid capacity degradation and short cycle life. The key to addressing these issues lies in suppressing the shuttle effect as well as inhibiting the growth of dendrites. In this work, we rationally designed a composite with heterostructured ZnSe-SnSe2 grown in situ on graphene-like oxidized carbon nitride (OCN) as a sulfur species immobilizer and a guiding agent for the uniform deposition of lithium ions in Li-S batteries. Benefitting from these, ZnSe-SnSe2, which has both thiophilic and lithophilic, enhances the ability of OCN to inhibit diffusion and catalyze the conversion of polysulfides, as thoroughly demonstrated from experimental to theoretical calculations. When ZnSe-SnSe2@OCN was coated onto the separator to be prepared as a functionalized separator, it demonstrated desirable electrochemical properties, including an initial discharge specific capacity of 1265 mAh g-1 (0.1C), a high-rate performance of 609 mAh g-1 at 5C, and a favorable cycling stability with 1C for 350 cycles with a decay rate of 0.11%. This work provides a viable solution for the design and preparation of functionalized separators for high-rate Li-S batteries.