Self-reduction preparation of porous multi-walled ZnCo2O4 spheres as sulfur host for lithium-sulfur battery cathodes with long cycling life and stable rate-performance

Current lithium-sulfur (LiS) batteries have some severe issues such as shuttle effect of polysulfides and volumetric expansion of sulfur, even though their high theoretical energy density is attractive. Herein, we present a porous multi-walled ZnCo2O4 sphere prepared by a self-reduction approach as sulfur host for LiS battery cathode. During the annealing of an inorganic-organic hybrid precursor, ZnCo2O4 spheres are partially reduced by the released carbon monoxide, resulting in the formation of ZnO and CoO nanoparticles which are subsequently etched by acid, finally forming mesopores throughout the multi-walled ZnCo2O4 spheres. The multi-walled ZnCo2O4 provides sufficient space for accommodating the volumetric change of sulfur. The adsorption measurements show that the multi-walled ZnCo2O4 can adsorb the polysulfides efficiently, which suppresses the shuttle effect. After cycling 1000 times at a rate of 0.5C, the multi-walled ZnCo2O4@S composite remains a capacity of 590 mAh g(-1). The rate-performance is well recoverable during repeated tests. Moreover, the capacities at relatively low and high temperatures of - 5 and 50 degrees C are 654 and 619 mAh g(-1) after 100 cycles, respectively, indicating a potential for applications

Automated summary

A porous multi-walled ZnCo2O4 sphere prepared by a self-reduction approach is proposed as a sulfur host for LiS battery cathode, providing sufficient space for accommodating volumetric change of sulfur and efficiently suppressing shuttle effect of polysulfides.