LiCoPO_4正极材料掺Zn^(2+)及全电池特性

Zn^(2+) doping of LiCoPO_4 cathode material and its full battery performance

采用柠檬酸溶胶-凝胶法合成锌离子(Zn^(2+))掺杂的磷酸钴锂(LiCoPO_4)正极材料LiZn_xCo_(1-x)PO_4。XRD和SEM分析表明:少量Zn^(2+)掺杂不会明显改变晶格结构,且粒径变小、粒度更均一。充放电(3.0~5.1V)及高低温性能测试表明:Zn2+掺杂后,材料的比容量提高、循环性能改善,并有较好的高倍率及高低温放电性能。Zn^(2+)掺杂量为0.01时,首次0.1 C放电比容量为150.3 mAh/g,比纯相增加15%。1.0C、5.0C放电比容量分别为118.9mAh/g和67.1mAh/g。在40℃、0℃下的0.1C放电比容量分别为160.0mAh/g和37.8mAh/g。循环伏安及交流阻抗测试表明:少量Zn^(2+)掺杂使电荷转移阻抗减小,电化学可逆性增强。LiZn_(0.01)Co_(0.99)PO_4与Li_4Ti_5O_(12)组成的3.3 V全电池以0.1C放电,比容量可达135.3mAh/g。

Zinc ion（Zn2 ＋ ） doped lithium cobalt phosphate（ LiCoPO4 ） cathode materials LiZnx Co1-xPO4 were prepared by the citric acid-based sol-gel method. XRD and SEM analysis showed that doping a small amount of Zn2＋ did not affected the lattice structure; the particle size was smaller and more uniform. Charge-discharge（3.0 -5. 1 V） and high/low temperature performance tests showed that the specific capacity was increased and cycle performance was enhanced after Zn2＋ doping, the material had fine high rate and high/low temperature performance. When the Zn2＋ doping amount was 0. 01, the initial specific discharge capacity of 0. 1 C was 150. 3 mAh/g,which was 15% higher than that of the pure one. The specific discharge capacity of 1.0 C and 5. 0 C was 118. 9 mAh/g and 67. 1 mAh/g,respectively. The specific discharge capacity of 0. 1 C at 40 ℃ and 0 ℃ was 160. 0 mAh/g and 37. 8 mAh/g, respectively. The charge transfer impedance was decreased and the reversibility of lithium extraction/insertion and electrochemical reaction were improved after Zn2＋ doping,via cyclic voltammetric and A. C. impedance spectroscopy tests. The specific capacity of 3.3 V full cell which composed of LiZn0.01Co0.99PO4 and Li4Ti5O12 was up to 135.3 mAh/g when discharged with 0. 1 C.