【摘要】 采用高温固相法2步合成了掺Cr的锂离子电池正极材料LiV1-xCrxPO4F(x=0,0.01,0.03,0.05,0.07),XRD测试表明LiV1-xCrxPO4F属三斜晶系。通过恒电流充放电,循环伏安和交流阻抗实验表明:掺Cr后LiVPO4F正极材料更有利于锂离子的嵌入和嵌出,材料的放电容量和循环性能进一步提高,例如,铬掺杂的LiVPO4F样品在室温、0.2C倍率下充放电,循环50周后容量在110mAh·g-1以上。文中还讨论了充放电容量随掺Cr量的关系,nCr含量为0.03的LiV1-xCrxPO4F有着较高的放电平台和良好的循环稳定性。更多还原

【Abstract】 A series of Cr-doped LiVPO4F cathode materials were synthesized by conventional solid-state reactions of the stoichiometric mixture of VPO4, CrPO4 and LiF, and the samples showed the same triclinic structure as the undoped LiVPO4F. The Cr-doped LiVPO4F samples were investigated on the Li extraction/insertion performances through galvanostatic charge/discharge, cyclic voltammetry (CV), and electrochemical impedance spectrum (EIS). The Cr-doped LiVPO4F systems showed improved capacity and cyclability in the voltage range of 3.0~4.6 V at different rates, for example, the measured discharge capacity of the Cr-doped LiVPO4F sample was still held over 110 mAh·g-1 after 50 cycles at 0.2 C rate at room temperature. The optimal doping content of Cr was that x=0.03 in the LiV1-xCrxPO4F samples to achieve high discharge capacity and good cyclic stability. The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through the Cr-doping. The improved electrochemical performances of the Cr-doped LiVPO4F cathode materials are attributed to the structural stability derived from the incorporation of Cr3+ ions.更多还原