A Trifunctional Separator Based on a Blockage-Adsorption-Catalysis Synergistic Effect for Li-S Batteries

To address the obstinate problem of the shuttle effect in lithium-sulfur (Li-S) batteries, cathode materials are usually given multifunctions to immobilize sulfur, which increases the processing difficulty of cathode materials and weakens the advantage in energy density of Li-S batteries. Herein, a single-source decomposition approach is employed to synthesize a pomegranate-like nitrogenous carbon-coated ZnS (ZnS@NC) precursor that is acid etched to obtain the partially etched ZnS@NC (PE-ZnS@NC) composite. PE-ZnS@NC is coated on a commercial PP separator to a fabricate PE-ZnS@NC/PP functional separator that is used to assemble a coin cell with the sulfur/super P cathode. The 3D network carbon framework of PE-ZnS@NC provides additional active sites for electrochemical reaction and a space barrier for the diffusion of the dissolved lithium polysulfides (LPS). Well-distributed N-containing functional groups and polar ZnS could chemically anchor LPS. Also, the ZnS nanoparticles inside could facilitate a fast kinetic process by catalyzing the liquid-liquid and liquid-solid conversion. Since the shuttle effect is greatly suppressed by the synergistic trifunctions of blockage-chemisorption catalysis, PE-ZnS@NC/PP delivers remarkable electrochemical performances that a self-discharge rate of 0.4% per day is achieved in the shelving test and a capacity retention of 97.0% is gained after 50 cycles at 0.5 C, under a sulfur-areal density of around 3 mg cm^-2.