Fabrication and characterization of N-doped porous carbon Co-Fe alloy composite cathode materials for promoting the electrochemical performance of Li-S batteries

Abstract

The cathode materials for lithium-sulfur battery, as a hot topic in energy storage research, is an important node for lithium sulfur battery to achieve practical application. Here, we prepared a nitrogen-doped carbon shell structured porous carbon-bimetal alloy composite with a particle diameter of 150 nm. In the shell of the structure, Co-Fe alloy particles as diameter of 20 nm with nitrogen-doped carbon coated were uniformly distributed. This porous nanocarbon materials have a rich surface area that can serve as a site for sulfur load. The uniform Co-Fe alloy catalytic and absorptive site can improve the oxidation-reduction reaction kinetics of LSBs and inhibit the shuttle effects of polysulfides. Meanwhile, the spatial domain restriction of the shell can be helpful to anchor S and polysulfides inside the structure. Because of these synergistic benefits, the Li-S batteries with this material cathode performs an excellent cycling stability with the capacity decay rate of 0.055% per cycle at 0.1 C after 100 cycles (initial capacity is 1226 mAh g−1) and 85.5% of initial capacity at 1 C after 300 cycles (initial capacity is 899.5 mAh g−1). Even with a high sulfur loading of 5.1 mg cm−2, it still achieves a high capacity of 3.43 mAh cm−2 (75% of initial capacity) after 100 cycles. This study provides the potential possibility to achieve large-capacity long-cycle work in lithium-sulfur batteries.