Structural Control of Nitrogen-Rich Carbon Nanosheets and Their Application in Sodium Ion Battery

针对钠离子电池负极材料存在的离子扩散缓慢和循环稳定性差等问题，本文提出磷掺杂富氮碳纳米片的结构调控策略。通过金属六胺框架前驱体的热解和磷化处理，成功制备了二维多孔磷氮共掺杂碳(P-N/C)纳米片材料。优化后的材料比表面积达1245 m2/g，氮含量为8.4 wt%，磷掺杂显著提升了吡啶氮和吡咯氮的比例至73.5%。电化学测试表明，该材料作为钠离子电池负极展现出438 mAh/g的首圈放电容量，2 A/g下循环500圈后仍保持246.6 mAh/g的可逆容量，库伦效率稳定在99%以上。研究表明，磷–氮 (P-N)协同效应和多孔结构是实现优异储钠性能的关键，为高性能钠离子电池负极材料的设计提供了新思路。In view of the problems of slow ion diffusion and poor cycle stability in the anode materials of sodium ion batteries, this paper puts forward the structural control strategy of phosphorus-doped nitrogen-rich carbon nanosheets. Two-dimensional porous P-N co-doped carbon (P-N/C) nanosheets were successfully prepared by pyrolysis and phosphating of metal hexamine framework precursor. The optimized material has a specific surface area of 1245 m2/g and a nitrogen content of 8.4 wt%, and phosphorus doping significantly increases the ratio of pyridine nitrogen to pyrrole nitrogen to 73.5%. The electrochemical test showed that the material, as the negative electrode of sodium ion battery, exhibited the first-cycle discharge capacity of 438 mAh/g, and the reversible capacity was still 246.6 mAh/g after 500 cycles at 2 A/g, and the coulombic efficiency was stable above 99%. The research shows that the synergistic effect of phosphorus and nitrogen (P-N) and porous structure are the key to achieve excellent sodium storage performance, which provides a new idea for the design of anode materials for high-performance sodium ion batteries.