Three-dimensional carbon foam decorated with SnO₂ as multifunctional host for lithium sulfur batteries

Lithium-sulfur (Li-S) batteries with high theoretical capacity and abundant sulfur resources are potential energy storage systems. Nevertheless, there are several roadblocks that strongly limit the commercial application of Li-S batteries, including the insulating nature of sulfur and Li₂S, large volume change and the shuttle effect of lithium polysulfides. Herein, a three-dimensional carbon foam (CF) decorated with SnO₂ (SnO₂/CF) is fabricated by the simple electrodeposition and used as a sulfur host to resolve the bottleneck issues in Li-S batteries. Thanks to the synergetic effect of the polar SnO₂ and conductive carbon framework, the SnO₂/CF framework is endowed with multifunctionalities such as providing three-dimensional conductive framework, inhibiting the migration of polysulfides and improved reaction kinetics. Consequently, durable cycle performance with a capacity of 458.2 mAh g^-1 after 1000 cycles at 1 C is achieved. Furthermore, a high capacity of 749.5 mAh g^-1 at a high rate of 5 C is attained. Remarkably, under high sulfur loading of 8.84 mg cm^-2, the S@SnO₂/CF cathode can still deliver a high specific capacity of 389.8 mAh g^-1 after 300 cycles at 0.5 C. This work demonstrates a novel strategy to improve the performance of Li-S batteries for energy storage applications.