Rational design of SnO2 thin film coated cathode with function of entrapping polysulfides for performance enhanced Li-S batteries

Lithium -sulfur (Li-S) batteries have faced challenges in large scale application due to the severe shuttle effect associated with lithium polysulfides (LiPSs). To solve this issue, magnetron sputtering (MS), a simple and effective deposition method, was used for the first time to deposit SnO2 thin films on the surface of Li-S battery cathodes composed of porous carbon and sulfur. By controlling the deposition time of sputtering, an optimized coating thickness was achieved. Combined with density functional theory (DFT) calculations, this work demonstrates the strong adsorption capacity of SnO2 for LiPSs can be used to enhance battery performance, and this enhancement effect is more obvious after increasing the cycle rate. As a result, the specific capacity of the battery with 5 nm SnO2 coated cathode (615.69 mAh/g) was 45.19 % higher than that of the uncoated battery after 100 cycles at a rate of 0.1C. After the charge and discharge rate was increased by 5 times, the specific capacity of the battery with 5 nm SnO2 coated cathode (604.93 mAh/g) was 157.32 % higher than that of the uncoated battery.