【摘要】 通过固相反应法合成出Li3+xFe2-xMnxⅡ(PO4)3(x=0~0.1)、Li3Fe1.95Mn0.Ⅲ05(PO4)3和Li2.95Fe1.95Mn0.Ⅳ05(PO4)3正极材料。采用行星式球磨方法,均匀混合正极材料和导电乙炔黑以提高活性材料的电子导电率和降低颗粒尺寸。Mn掺杂的Li3Fe2(PO4)3样品的恒电流充放电测试和伏安循环测试(2~4V)发现,所有样品中Fe3+/Fe2+氧化还原电对均有两个稳定的充放电平台(2.8、2.7V)、Li3+xFe2-xMnxⅡ(PO4)3和Li3Fe1.95Mn0Ⅲ.05(PO4)3中Mn3+/Mn2+电对的充放平台位于3.5V左右。不同价态Mn的掺杂均可明显提高正极材料的电化学性能,其中MnⅡ掺杂样品的电化学性能最好,其中Li3.05Fe1.95MnⅡ0.05(PO4)3/C的C/20和C/2恒流放电比容量分别可达110和66mAh/g。更多还原

【Abstract】 The monoclinic Li3+xFe2-xMnⅡx(PO4)3(x=0-0.1),Li3Fe1.95MnⅢ0.05(PO4)3 and Li2.95Fe1.95MnⅣ0.05(PO4)3 cathodes were synthesized by solid state reaction.The synthesized powders were ball-milled with acethylene carbon to reduce the particle sizes and improve the electronic conductivity of the active materials.The galvanostatic charge/discharge test and the cyclic voltammetry(C-V) revealed that all of them had two plateau potentials of Fe3+/Fe2+ couple vs.Li/Li+ at 2.8 and 2.7V upon discharge.The plateau potential of Mn3+/Mn2+ at 3.5V was observed in Li3+xFe2-xMnⅡx(PO4)3 and Li3Fe1.95MnⅢ0.05(PO4)3 cathodes.Furthermore,the Mn doping was demonstrated to be able to improve the electrochemical performances of the cathodes.In all the samples,the Li3.05Fe1.95MnⅡ0.05(PO4)3/C cathode showed the best electrochemical performances and possessed the discharge capacities of 110mAh/g at C/20 and 66mAh/g at C/2.更多还原