MoO_4^(2-)取代对Nasicon型Li_3Fe_2(PO_4)_3正极材料电化学性能的影响  

Effect of MoO_4^(2-) Substitution on Electrochemical Properties of Nasicon Li_3Fe_2(PO_4)_3 Cathode

作　　者：张勃[1] 何珺[1] 华正伸 鲁豪祺 王新[1] 彭会芬[1,2] 

机构地区：[1]河北工业大学材料科学与工程学院,天津300130 [2]天津市材料层状复合与界面控制技术重点实验室,天津300130

出　　处：《无机化学学报》2016年第12期2109-2116,共8页Chinese Journal of Inorganic Chemistry

基　　金：河北省自然科学基金(No.E2016202358)资助项目

摘　　要：以MoO_4^(2-)部分取代Li3Fe2(PO4)3中的PO_4^(3-),研究表明:加入的MoO_4^(2-)离子主要以固溶形式存在于Li3Fe2(PO4)3中,起到了显著改善其电化学性能的作用。其中,MoO_4^(2-)掺杂浓度为0.3的样品表现出最佳的电化学性能,其在0.5C倍率下的首次放电容量为113.7 m Ah·g^(-1),这一数值比未掺杂的提高了20.7%;经过60次循环充放电,容量保持率为94%。将放电倍率从0.5C逐步增大至5C,再降至初始的0.5C,并在每个倍率循环10次,这一材料的最终放电容量可达首次0.5C的95%。这些优异的性能应归因于MoO_4^(2-)掺杂使材料的氧化还原能力增强,氧化还原电对的电势差减小,电池内部的电荷转移电阻减小,以及Li+扩散系数增加。MoO4 2- polyanion was tried to substitute for PO4 3- partially in the Li3Fe2 （PO4）3 compound. The results proved that the introducedMoO4 2- anions mainly dissolved in the Li3Fe2 （PO4）3 and the corresponding electrochemical properties were improved apparently. Among the MoO4 2- substituted materials, the sample with MoOfi- content of 0.3 presented the excellent electrochemical properties. Its initial discharging capacity was 113.7 mAb.g-1 at a rate of 0.5C, which was about 20.7% higher than that without any MoO42-. The capacity retention was about 94% at a rate of 0.5C after 60 cycles. Moreover, this material could restore 95% of the initial capacity when the discharging rate was reset back to 0.5C even after higher cycling rate of 5C. The boost in electrochemical properties for the MoO42- substituted samples is ascribed to the synergistic effects of improved redox ability, decreased potential polarization and charge transfer resistance as well as increased diffusion coefficient of lithium ions.

关 键 词：正极材料 锂电池 混合阴离子效应 阴离子掺杂 电化学性能 

分 类 号：TQ152[化学工程—电化学工业] O614.612[理学—无机化学]