Ni，Cr 掺杂对 Li FePO4／C电化学性能的影响

Effect of Ni,Cr doping on the electrochemical performances of LiFePO4/C

摘要:

采用二步固相反应在惰性气氛下合成了橄榄石型LiFe0．98M0．02PO4／C（M＝Ni，Cr）复合正极材料．通过XRD，SEM及电化学测试等手段对材料的性能进行分析．研究结果表明：少量Ni2＋，Cr3＋的掺杂虽然未改变LiFePO4晶体结构，但改善了材料的颗粒形貌，降低了粒径（粒径约200nm），增强了LiFe0．98M0．02PO4／C材料的导电能力，比未掺杂的LiFePO4／C具有更好的电化学性能．在2．5～4．2V下充放电，LiFe0．98Cr0．02PO4／C材料0．2C的首次放电比容量为146．7mA·h·g－1，循环50次的容量保持率为98．1，，10C放电比容量达116．3mA·h·g－1．

Abstract:

In this study ,olivine LiFe0 .98 M0 .02 PO4/C(M= Ni ,Cr) composite cathode materials were synthe‐sized by the two‐step solid state reaction method in an inert atmosphere .The performances of the obtained materials were analyzed by XRD ,SEM and electrochemical tests .The results indicated that the structure of lithium iron phosphate was not changed ,while both its particle morphology (the particle size was re‐duced to 200nm) and conductivity of LiFe0 .98 M0 .02 PO4/C materials were improved by doping of small a‐mounts of Ni2+ ,Cr3+ .The better electrochemical performance for the doped materials was obtained than that of the pristine LiFePO4/C .When the material LiFe0 .98 Cr0 .02 PO4/C was charged‐discharged at 2 .5 -4.2 V ,the discharge capacity of 146 .7 mA · h · g -1 was exhibited initially and retained 98 .1， after 50 cy‐cles at 0 .2C ,and the 10 .0C discharge capacity was achieved to 116 .3 mA · h · g -1 .