LiCoPO_4正极材料掺Zn~(2+)及全电池特性

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。

Zn2+ doping of LiCoPO4 cathode material and its full battery performance

Zinc ion(Zn2 +) doped lithium cobalt phosphate(LiCoPO4) cathode materials LiZnx Co1-x PO4 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.