可用于航空锂电池正极材料LiFePO_4氮掺杂碳包覆改性研究

A Modification Study of the N-doped Carbon-coated LiFePO_4 Cathode Material for Aeronautics Lithium-Ion Battery

以二氰二胺为氮掺杂剂,采用溶胶凝胶法制备了氮掺杂碳包覆LiFePO_4的复合材料,并且分析了氮掺杂量对电极材料结构与性能的影响。研究结果表明,柠檬酸和二氰二胺在高温下的原位分解使合成的LiFePO_4颗粒表面包覆了一层氮掺杂的碳膜,有效的增加了各颗粒间的电接触,改善了LiFePO_4的电化学性能。当氮掺杂量为0.35 wt%时,LiFePO_4@N_(0.35%)C样品具有最优良的电化学性能。在2.5~4.2 V的电压范围内,电极材料在0.1 C倍率下的首次放电比容量达到157.2 mAh/g,经过30个循环后放电容量基本不变。

The N-doped carbon-coated LiFePO4 composite is prepared by the sol-gel method taking C2 H4 N4 as the nitrogen source. Meanwhile, the effect of nitrogen contents on the structure and property of LiFe- PO4 @C is investigated. The obtained results show that the citric acid and Cz H4N4 decompose in-situ form- ing a N-doped carbon layer covering the surface of LiFePO4 particles during the sintering process, effec- tively enhance the electronic contact between the LiFePO4 particles, and improve the electrochemical per- formance of LiFePO4 electrode material. When the nitrogen content in LiFePO4 NC is 0. 35 wt, the corresponding electrode exhibits the best electrochemical performance. The initial discharge capacity of LiFePO4No.C reaches 157.2 mAh/g at 0.1 C between 2.5 V and 4. 2 V, and this capacity almost re- mains unchanged after 30 cycles.