Cobalt nanoparticle-embedded N-doped hierarchically porous carbon as electrocatalyst in lithium sulfur batteries

The effective inhibition of lithium polysulfides (LiPSs) and promotion of their conversion in the redox processes are indispensable to achieve the long cycle stability and excellent rate performance of lithium-sulfur (Li–S) batteries. Herein, cobalt nanoparticle-embedded N-doped hierarchically porous carbon (Co/N-HPC) was prepared via a simple method, using the sodium citrate as complexing agent and carbon source. Such a rationally designed structure is conducive to the adsorption/catalytic conversion of intermediate lithium polysulfides, which reduces the polarization and facilitates the efficient usage of active sulfur. Due to these merits, the Co/N-HPC/S cathode achieves an initial discharge capacity up to 1114.3 mAh g−1 at 0.2 C and still remains 768.9 mAh g−1 after 200 cycles. The discharge capacity of the first cycle is 530 mAh g−1 at high rate of 3C. Co/N-HPC/S cathode exhibits good cycle stability and rate capabilities.