Abundant Canadian pine with polysulfide redox mediating ZnS/CuS nanocomposite to attain high-capacity lithium sulfur battery

A new strategy is presented to immobilize the lithium polysulfides (LiPSs) and promote charge transfer kinetics at the S-electrode interface of lithium-sulfur (Li–S) batteries. In this work, biomass-derived porous carbonized pine (p-Cp), abundantly available in Canada, is used as the carbon host for S electrode in the Li–S batteries. A multifunctional composite electrocatalyst – zinc sulfide/copper sulfide (ZnS/CuS - ZCS) - is prepared through a simple chemical reaction involving successive immersion approach. The mesoporous p-Cp efficiently encapsulate the sulfur particles and provides sufficient pore volume to accommodate expansion/contraction of sulfur cathode during the charging-discharging processes. The nanostructured ZCS composite facilitates the liquid-solid phase conversion of lithium polysulfides (LiPSs) to Li₂S to limit the LiPSs dissolution in the electrolyte. Our systematic investigation reveals that the CuS accelerates the electron transfer process while ZnS lowers the energy barrier for LiPSs redox kinetics in the composite electrode. Benefiting from the synergistic effect, the p-CpZCS/sulfur cathode achieves a high specific discharge capacity of about 1457 mAh g⁻¹ at a rate of 0.1 C.