磷掺杂石墨相氮化碳的制备及其在锂硫电池中的应用

通过热缩聚合成法，采用尿素为原料，制备石墨相氮化碳(g-C₃N₄)，以磷酸氢二胺作为磷源，制备不同磷含量的磷掺杂g-C₃N₄ (xP-CN)，研究磷掺杂对xP-CN的微观结构、形貌及xP-CN/S复合材料作为锂硫电池正极材料电化学性能的影响。研究表明，磷掺杂后xP-CN的层间距增大，导电性提高，比表面积变大，10% P-CN的比表面积最大达到101.741 m2·g?1。10% P-CN/S复合材料在0.05 C (1 C=1675 mA·h·g?1)下首次放电比容量达到1383.8 mA·h·g?1，在0.2 C下循环100次后可逆比容量为860.0 mA·h·g?1，而g-C₃N₄/S复合材料比容量仅为178.3 mA·h·g?1；10% P-CN/S复合材料经过倍率测试后比容量可以回复到0.2 C时的93.6%，表现出良好的循环性能和倍率性能。 

Preparation of phosphorus-doped graphitic carbon nitride and its application in lithium-sulfur batteries

Graphite-phase carbon nitride (g-C₃N₄) was prepared by heat shrinkage polymerization method using urea as raw material, and phosphorus-doped g-C₃N₄ with different phosphorus content (xP-CN) was prepared by using hydrogen phosphate diamine as a phosphorus source. The effect of doping on the microstructure, morphology, and electrochemical performance of xP-CN/S composites as cathode materials for lithium-sulfur batteries was studied. The studies show that the layer spacing of xP-CN increases after phosphorus doping, the electrical conductivity increases, and the specific surface area becomes larger. The specific surface area of the 10% P-CN reaches 101.741 m2·g?1. The initial discharge specific capacity of the 10% P-CN/S composite at 0.05 C (1 C=1675 mA·h·g?1) reaches 1383.8 mA·h·g?1. The reversible specific capacity after 100 cycles at 0.2 C is 860.0 mA·h·g?1, the reversible specific capacity of g-C₃N₄/S composite is only 178.3 mA·h·g?1; The specific capacity of 10% P-CN/S composite can be restored to 93.6% at 0.2 C after the rate test, showing good cycle performance and rate performance.