Double hollow spherical SnO2@Co3O4 applied to separator for efficient catalysis of polysulfides in lithium-sulfur batteries

Abstract

High energy density lithium-sulfur batteries have been greatly suffered by the shuttle effect of lithium polysulfides. In this work, SnO2@Co3O4 double hollow spheres are synthesized to form a unique heterojunction structure that can efficiently catalyze and strongly absorb the regulation of polysulfides, which can catalyze the conversion of needle-like polysulfides into flower-like structures when applied in separator modification, effectively blocking the polysulfides in the cathode side and greatly improving the battery performance and cycle stability. At 0.5C current density, the initial discharge specific capacity of SnO2@Co3O4 separator battery is 893 mAh g−1, and its capacity degradation rate is only 0.082 % in 500 turns of cycling. Under harsh conditions (sulfur areal density = 6 mg cm−2, E/S = 5 μL mg−1), SnO2@Co3O4 separator cells can also achieve an area capacity of 4.03 mAh cm−2 at 0.1C. Additionally, the SnO2@Co3O4 separator cells also have high stability and cycling performance at different temperatures.