LiMO2@Li2MnO3 positive-electrode material for high energy density lithium ion batteries
LiMO2@Li2MnO3 positive-electrode material for high energy density lithium ion batteries
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高能量密度锂离子电池正极材料LiMO2@Li2MnO3
DOI：
10.1007/s10008-016-3345-x
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发表时间：
2016
影响因子：
2.5
通讯作者：
L. Lei
中科院分区：
文献类型：
--
作者：
M. Mezaal;L. Qu;Guanghua Li;Wei Liu;Xiaoyuan Zhao;Ke Zhang;R. Zhang;L. Lei
Li[Ni1/3Co1/3Mn1/3]O2(NCM 111)具有价格低廉、结构稳定、安全性好等优点，是一种很有前途的LiCoO2替代物。然而，其155mAg−1的容量很低，在4.5V以上的电位下循环会导致容量迅速恶化。在这里，我们成功地合成了以LiMo_2(R-3m，M = Ni，Co)为核，Li_2MnO_3(C2/m)为壳层的富锂层状氧化物(LLO)。用X射线衍射仪、透射电子显微镜和X射线光电子能谱对其核壳结构进行了表征。Rietveld精修数据表明，与NCM111相比，这些LLO具有较少的Li+/Ni2+阳离子无序和较强的M*-O(M* = ，Mn，Co，Ni)键。核壳材料Li1.15Na0.5(Ni1/3Co1/3)壳O2可以循环到4.7nV的高上截止电位，在20 mA的−1下放电容量高达218mAhg−1，90周后在100 mA的−1下仍保持90%的放电容量，因此，将该材料用于锂离子电池可以显著提高其能量密度。核壳材料和原始材料的平均电压与循环次数在20 mA−1下循环10次，然后在100 mA/g−1下循环90次。
Li[Ni1/3Co1/3Mn1/3]O2(NCM 111) is a promising alternative to LiCoO2, as it is less expensive, more structurally stable, and has better safety characteristics. However, its capacity of 155 mAh g−1is quite low, and cycling at potentials above 4.5 V leads to rapid capacity deterioration. Here, we report a successful synthesis of lithium-rich layered oxides (LLOs) with a core of LiMO2(R-3m, M = Ni, Co) and a shell of Li2MnO3(C2/m) (the molar ratio of Ni, Co to Mn is the same as that in NCM 111). The core–shell structure of these LLOs was confirmed by XRD, TEM, and XPS. The Rietveld refinement data showed that these LLOs possess less Li+/Ni2+cation disorder and stronger M*–O (M* = Mn, Co, Ni) bonds than NCM 111. The core–shell material Li1.15Na0.5(Ni1/3Co1/3)core(Mn1/3)shellO2can be cycled to a high upper cutoff potential of 4.7 V, delivers a high discharge capacity of 218 mAh g−1at 20 mA g−1, and retains 90 % of its discharge capacity at 100 mA g−1after 90 cycles; thus, the use of this material in lithium ion batteries could substantially increase their energy density.Graphical AbstractAverage voltage vs. number of cycles for the core–shell and pristine materials at 20 mA g−1for 10 cycles followed by 90 cycles at 100 mA g−1