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.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
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
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
cathode
lithium battery
mixed anion effect
anion substitution
electrochemical properties
