Tungsten-Nitride-Coated Carbon Nanospheres as a Sulfur Host for High-Performance Lithium-Sulfur Batteries

Lithium-sulfur batteries have attracted wide attention, owing to their outstanding properties such as high theoretical specific capacity, low cost, and non-toxic nature. However, the low conductivity of the sulfur cathode and its shuttling effects are still a challenge for the energy-storage system. In this work, we describe a potential solution to address this challenge, using carbon nanospheres encapsulated in a tungsten nitride (WN) layer, interconnected with WN nanorods. After successfully synthesizing this composite in situ by using a straightforward method, we applied it as the sulfur host for lithium-sulfur batteries. The results demonstrate a strong chemical trapping ability of the WN shell towards lithium polysulfides (LiPSs), and a strong electron-transfer ability of the WN nanorods. Together, these effects alleviate LiPSs ' shuttling from carbon nanospheres (CNS) and give rise to a high sulfur content (70 wt %) in the as-prepared S/WN-CNS material. When compared to traditional S/N-CNS electrodes, the tuned S/WN-CNS cathodes deliver an outstanding electrochemical performance, including a high initial capacity of 1351 mAh g(-1) at 0.1 C and superior long-term cycling stability with 80 % retention of the initial capacity with 3 mg cm(-2) after 500 cycles at 0.5 C. As such, a high specific capacity, excellent rate capacity, and long cycling stability are achieved. Our approach provides a path to a broad class of high-performance Li-S battery applications based on nanostructured WN materials.