Vanadium-doped graphitic carbon nitride for high performance lithium–sulfur batteries

To promote polysulfide conversion in lithium sulfur batteries (LSB) and alleviate the shuttle effect, we designed and fabricated a novel catalyst of vanadium-doped graphite phase carbon nitride with nitrogen defects (V@gC₃N₄-ND) and high vanadium loading (3.46 at%) by defect engineering and two-step pyrolysis. Employing a V@gC₃N₄-ND modified separator, the LSB yielded capacities of 934 mA h g^-1 at 1C and 404 mA h g^-1 at 4C; the former was retained by 61% and 45% after 500 and 1000 cycles, respectively. In particular, the initial capacity of the battery reached 969 mA h g^-1 at a sulfur loading of 10.0 mg cm^-2. This work provides a facile route to the preparation of high-loading vanadium active site catalysts with nitrogen defects in the support, which are promising for high performance LSB applications.