B, N co-doped 3D hierarchical porous carbon entrapping sulfur for high performance of Li-S batteries

The dissolution and diffusion of polysulfide compounds in lithium-sulfur (Li-S) batteries restrict their cyclic stability. The sulfur hosts are the key to achieve good cyclic stability for Li-S batteries. Here, a three-dimensional hierarchical heteroatoms B, N-doped porous carbon (BNC) was prepared as a new sulfur host. The active sulfur can be anchored inside the cathode due to the incorporation of atomic functional groups formed by B and N co-doping, which enhances the adsorption capacity between the cathode and lithium polysulfides. The resulting BNC loaded sulfur (S@BNC) cathode exhibits high specific capacity and electrochemical stability. Specifically, the reversible specific capacity of S@BNC cathode achieved a reversible specific capacity of 1056.8 mAh g⁻¹ at 0.1 C. After 500 cycles, the specific capacity still remains 618.5 mAh g⁻¹ at 0.2 C, which corresponds to a capacity decay rate of 0.0776 %. The results suggest that BNC has great potential as the sulfur host for achieving high performance of Li-S batteries.