用水热法制备LiFe0.95M0.05PO4(M = Mg, Ni, Co), 研究了掺杂对材料电化学性能的影响. 结果表明, 液相Fe位掺杂合成的LiFe 0.95 M 0.05PO4具有纯相橄榄石结构、结晶良好、粒径均匀; Fe位掺杂可增强材料的可逆性和导电性, 提高其1C倍率下的电化学容量和循环稳定性; LiFe0.95Mg 0.05PO4, LiFe 0.95 Ni 0.05 PO 4 和LiFe 0.95 Co 0.05 PO 4三种材料的1C倍率首次放电比容量分别为133.1 mAh ?g-1, 128.4 mAh ?g -1 和135.2 mAh ? g -1; 三种掺杂离子中Co 2+掺杂的效果最好, 0.1C和1C倍率放电循环30次后的容量衰减率仅为5.7%和9.5%.
LiFe 0.95 M 0.05 PO 4 (M=Mg, Ni, Co) were synthesized by hydrothermal process with Fe-site doping in liquid phase. The samples of LiFe0.95 M 0.05 PO 4 were characterized by XRD, FTIR and SEM methods. The effect of Fe-site doping on electrochemical properties of the samples was investigated. The results show that the electrochemical capacity and cyclic stability of LiFe 0.95 M 0.05 PO 4 at 1C are enhanced. Under 1C rate, the first discharge capacity of LiFe 0.95 Mg 0.05 PO 4, LiFe 0.95 Ni 0.05 PO 4 and LiFe 0.95 Co 0.05 PO 4 exhibit 133.1 mAh·g−1, 128.4 mAh·g−1 and 135.2 mAh·g−1, respectively. In three doping ions, the result of Co 2+ doping is the best. The capacity fading rates of LiFe 0.95 Co 0.05 PO 4 are 5.7% at 0.1C and 9.5% at 1C after 30 cycles. Such a significant improvement of electrochemical performance at 1C rate should be related to the enhancement of the reversibility and conductivity of LiFePO4 doped by bivalent cation
in Fe-site.
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