Ni@Ni₃N Embedded on Three-Dimensional Carbon Nanosheets for High-Performance Lithium/Sodium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries are recognized as one of the most promising next-generation energy storage devices, but their practical application is greatly limited by several obstacles, such as the highly insulating nature and sluggish redox kinetics of sulfur and the dissolution of lithium polysulfides. Herein, three-dimensional carbon nanosheet frameworks anchored with Ni@Ni3N heterostructure nanoparticles (denoted Ni@Ni3N/CNS) are designed and fabricated by a chemical blowing and thermal nitridation strategy. It is demonstrated that the Ni@Ni3N heterostructure can effectively accelerate polysulfide conversion and promote the chemical trapping of polysulfides. Meanwhile, the carbon nanosheet frameworks of Ni@Ni3N/CNS establish a highly conductive network for fast electron transportation. The cells with Ni@Ni3N heterostructures as the catalyst in the cathode show excellent electrochemical performance, revealing stable cycling over 600 cycles with a low-capacity fading rate of 0.04% per cycle at 0.5 C and high-rate capability (594 mAh g–1 at 3 C). Furthermore, Ni@Ni3N/CNS can also work well in room-temperature sodium–sulfur (RT-Na/S) batteries, delivering a high specific capacity (454 mAh g–1 after 400 cycles at 0.5 C). This work provides a rational way to prepare the metal–metal nitride heterostructures to enhance the performance both of Li–S and RT-Na/S batteries.