CeO2-C nanorods obtained by high-temperature carbonization of Ce-MOF as separator coating for Li-S battery

Abstract

Lithium-sulfur batteries (LSBs) are of great interest to researchers due to their high theoretical specific capacity and high energy density. Unfortunately, because of sulfur's weak conductivity and the shuttle effect of polysulfides, the application prospects of LSBs are facing great challenges. To suppress the shuttle effect of polysulfides, nanorod-like CeO2 and CeO2-C using Ce-MOF as the precursor was successfully prepared and applied to the separator of LSBs. Coating CeO2 and CeO2-C obtained by calcination in different atmospheres on PE separators can effectively enhance the electrochemical properties of LSBs due to the excellent chemisorption and catalytic effect of CeO2 on lithium polysulfides. In particular, CeO2-C which is obtained by calcination of Ce-MOF in N2 atmosphere has abundant micro and meso porous structures, which can quickly adsorb polysulfide in the electrolyte and accelerate the redox kinetics at the same time. Moreover, the nano-rod structure of CeO2 and CeO2-C also improves the conductivity of the separator. After a series of electrochemical tests, it was discovered that the discharge capacity of the CeO2-C coated separator battery on the first cycle was 1240 mA h g−1 when the cathode sulfur loading was approximately 2.5 mg cm−2, and that the discharge capacity remained 520 mA h g−1after 500 loops at 0.5 C. Even when the sulfur loading reaches 5.5 mg cm−2, it also has a good cyclic stability, demonstrating its application potential.