Nitrogen-doped cross-linked carbon nanosheets-loaded CdB2O4 nanoparticles as efficient sulfur host for lithium-sulfur battery

Three-dimensional interconnected nitrogen-doped carbon nanosheet-(NCNs) loaded cadmium borate (CdB2O4) nanoparticles were prepared using a soak-dry-calcine process. CdB2O4 nanoparticles were well dispersed and anchored on the carbon nanosheets. Applied in sulfur cathode of lithium-sulfur battery, the CdB2O4-based composite delivered a stable capacity of 666.8 mAh g-1 over 400 cycles at 0.5 A g-1 with a high coulombic efficiency of 99%. It maintained 449.9 mAh g-1 at 1.0 A g-1 after 500 cycles, with a decay rate of 0.065% per cycle. The superior electrochemical performance of the nanocomposite was due to the abundant mesopores, which could encapsulate more active sulfur and alleviate the volume expansion caused by discharge procedure. Furthermore, the CdB2O4 nanoparticles anchored on the nanosheets effectively confined the lithium polysulfides and exhibited a high electrocatalysis effect toward the conversion of polysulfides in the charge-discharge process.