Porous Carbon Nanosphere with Multiple Heteroatom Doping Derived from Silicon Oxycarbonitride as Sulfur Host for Lithium–Sulfur Batteries

The porous carbon nanosphere with multiple heteroatom doping derived from silicon oxycarbonitride (SiOCN) with an interconnected carbon and silica domains is reported as a robust host of the sulfur cathode for lithium–sulfur batteries. The synthesis of the porous carbon nanosphere (SiOCN‐H) is straightforward etching spherical SiOCN prepared through pyrolysis of a Schiff‐base‐SiO 2 precursor. The pore structure of SiOCN‐H can be easily adjusted by altering the amount of tetraethyl orthosilicate added in the aldimine condensation reaction of 3‐aminopropyl‐triethoxysilane with glutaraldehyde. The optimized sample of SiOCN‐H‐1 possesses a larger pore volume of 1.433 cm 3 g −1 and contains multiple heteroatoms of Si, O, and N with a total amount of about 21 wt%. The sulfur cathode based on SiOCN‐H‐1 exhibits decent cycling performance, retaining 77.2% of the initial capacity at 0.2C after 100 cycles. At 0.5C, the S/SiOCN‐H‐1 cathode still maintains remarkable cycling stability, delivering a reversible discharge capacity of 540 mAh g −1 after 400 cycles with a low decay of 0.076% per cycle. The porous spherical structure and the chemical bonding capability of doped heteroatoms in SiOCN‐H‐1 primarily contribute to the high performances of the S/SiOCN‐H‐1 cathode by alleviating the dissolution and shuttle effect of polysulfides.