A Ti3C2Tx MXene - carbon nanocage - sulfur cathode with high conductivity for improving the performance of Li-S batteries

Lithium-sulfur (Li-S) batteries hold their promise in renewable next-generation energy storage technologies due to low cost and high theoretical energy. Herein, a Ti3C2Tx MXene-carbon nanocage-sulfur (MXene/CNC/S) cathode is synthesized by a simple process with high conductivity and outstanding performance in Li-S batteries. The cathode with an unusually high sulfur content of 80% demonstrates an eminent initial specific capacity of 1275.5 mAh·g−1 at 0.1 C and retains 823.8 mAh·g−1 after 100 cycles, showing a high retention rate of 64.6%. Besides, it exhibits a great conductive feature for rate performance, delivering 630.5 mAh·g−1 capacity when the current rises to 4 C. In this composition electrode, the excellent electrochemical performance indicates that MXene can effectively adsorb polysulfides to help batteries achieve long-term cyclic performance. On the other hand, the introduction of CNC strongly improves the specific surface area of the cathode and constructs a high conductive network to reduce the stacking of MXene, thus exhibiting better rate performance and increasing utilization of sulfur. Our work holds future technological significance as it could accelerate progress towards lithium-sulfur batteries with high sulfur content and less pricy conductive materials.