LiMn0.5Fe0.5PO4 solid solution materials synthesized by rheological phase reaction and their excellent electrochemical performances as cathode of lithium ion battery
LiMn0.5Fe0.5PO4 solid solution materials synthesized by rheological phase reaction and their excellent electrochemical performances as cathode of lithium ion battery
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流变相反应合成的LiMn0.5Fe0.5PO4固溶体材料及其作为锂离子电池正极的优异电化学性能
DOI：
10.1016/j.jpowsour.2013.01.184
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发表时间：
2013-07
影响因子：
9.2
通讯作者：
Sun, Shi-Gang
中科院分区：
文献类型：
--
作者：
Zhong, Yan-Jun;Li, Jun-Tao;Wu, Zhen-Guo;Guo, Xiao-Dong;Zhong, Ben-He;Sun, Shi-Gang
以硬脂酸为碳源，通过流变相反应合成了碳包覆的LiMn0.5Fe0.5PO4固溶体材料（LiMn0.5Fe0.5PO4/C），并通过X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、BET和TG/DTG进行表征。结果表明，得到了结晶良好的橄榄石结构LiMn0.5Fe0.5PO4纳米片，无明显杂质相。合成的材料作为锂离子电池的正极并通过恒电流充放电测试进行研究。结果表明，与相同流变相反应路线合成的不同Mn:Fe比的LMFP材料（LiMn0.2Fe0.8PO4/C和LiMn0.8Fe0.2PO4/C）相比，LiMn0.5Fe0.5PO4/C表现出优异的倍率比性能，可提供138、99、80、72、67和67的放电容量。分别在 0.1、1、5、10、15 和 20C 倍率下为 55 mAh g−1。此外，该电极还具有良好的循环稳定性。室温充放电300次循环后，1C下的比容量达到100mAh g−1，容量保持率达到95%。 LiMn0.5Fe0.5PO4/C阴极电化学性能的显着改善归因于均匀分布的颗粒以及源自初级颗粒表面碳涂层的电导率的增强。
Carbon coated LiMn0.5Fe0.5PO4solid solution materials (LiMn0.5Fe0.5PO4/C) are synthesized by rheological phase reaction with stearic acid as carbon source, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET and TG/DTG. The results show that well-crystallized olivine structure LiMn0.5Fe0.5PO4nanoplatelets with no obvious impurity phase are obtained. The as-synthesized materials are served as cathode of lithium ion battery and investigated by galvanostatic charge/discharge tests. The results demonstrate that, in comparison with the LMFP materials of different Mn:Fe ratio (LiMn0.2Fe0.8PO4/C and LiMn0.8Fe0.2PO4/C) synthesized by the same route of rheological phase reaction, the LiMn0.5Fe0.5PO4/C exhibit excellent rate specific capability, and can deliver discharge capacity of 138, 99, 80, 72, 67 and 55 mAh g−1at respectively 0.1, 1, 5, 10, 15 and 20C rates. Moreover, the electrode possesses good cycle stability. A specific capacity of 100 mAh g−1at 1C after 300 cycles of charge–discharge at room temperature is reached, which represents 95% of capacity retention. The significantly improved electrochemical performances of the LiMn0.5Fe0.5PO4/C cathode are attributed to the uniformly distributed particles and the enhancement of conductivity that is originated from the surface coating of carbon on primary particles.