Effect of surface fluorine substitution on high voltage electrochemical performances of layered LiNi0.5Co0.2Mn0.3O2 cathode materials
Effect of surface fluorine substitution on high voltage electrochemical performances of layered LiNi0.5Co0.2Mn0.3O2 cathode materials
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DOI：
10.1016/j.apsusc.2016.02.224
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发表时间：
2016-05
影响因子：
6.7
通讯作者：
Dingzheng Wang;Zhixing Wang;Xinhai Li;Huajun Guo;Yan Xu;Yulei Fan;Wei Pan
中科院分区：
文献类型：
--
作者：
Dingzheng Wang;Zhixing Wang;Xinhai Li;Huajun Guo;Yan Xu;Yulei Fan;Wei Pan
提出了一种表面氟替代策略来提高LiNi0.5Co0.2Mn0.3O2材料的高压电化学性能。通过Rietveld精细化方法计算得到的晶格参数推算出掺氟后的晶格间距，从而使晶格间距变宽。扫描电子显微镜表明，氟取代促进了一次粒子的生长。虽然LiNi0.5Co0.2Mn0.3O2-ZFZ(z=0.02，0.04，0.06)的首次放电容量有所降低，但高氧化态下的容量保持率比裸电极有所提高。当LiNi0.5Co0.2Mn0.3O1.98F0.02的最佳组成为LiNi0.5Co0.2Mn0.3O1.98F0.02时，经100次循环后，1C的容量保持率为81.1%，10C时的放电容量为123.5 mAhg−1，而裸样品的放电容量仅为70.1%和109.6 mAhg−1。循环伏安和电子阻抗谱测试表明，氟掺杂可以显著降低电池极化，延缓阻抗上升。对循环电极的透射电子显微镜分析表明，氟替代可以有效地保护电极不受HF的侵蚀，从而永久地保持整体结构的稳定。
A strategy of surface fluorine substitution to enhance the high voltage electrochemical performance of LiNi0.5Co0.2Mn0.3O2material has been proposed. The inter-slab spacing distance is broaden by fluorine doping, which is deduced from the lattice parameters calculated by Rietveld refinement method. Scanning electron microscopy indicates the fluorine substitution stimulates the growth of the primary particles. Though the initial discharge capacities of LiNi0.5Co0.2Mn0.3O2-zFz(z = 0.02, 0.04, 0.06) is somewhat reduced, the capacity retention under high oxidation state were improved compared to that of bare one. For the optimal composition of LiNi0.5Co0.2Mn0.3O1.98F0.02, it exhibits a capacity retention of 81.1% at 1C after 100 cycles and delivers a discharge capacity of 123.5 mAh g−1at 10C, and that of bare sample are just 70.1% and 109.6 mAh g−1, respectively. Cyclic voltammetry and electron impedance spectroscopy measurements demonstrate that the fluorine doping could significantly lower the cell polarization and retard the impedance rise. Transmission electron microscope analysis of cycled electrodes is also performed and it implies that fluorine substitution can effectively safeguard the electrode from HF erosion to maintain the bulk structural stable permanently.