Anion Redox Chemistry in the Cobalt Free 3d Transition Metal Oxide Intercalation Electrode Li[Li0.2Ni0.2Mn0.6]O2
Anion Redox Chemistry in the Cobalt Free 3d Transition Metal Oxide Intercalation Electrode Li[Li0.2Ni0.2Mn0.6]O2
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DOI：
10.1021/jacs.6b05111
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发表时间：
2016-09-07
影响因子：
15
通讯作者：
Bruce, Peter G.
中科院分区：
文献类型：
--
作者：
Luo, Kun;Roberts, Matthew R.;Bruce, Peter G.
用于锂电池的常规嵌入阴极在与过渡金属阳离子相关的氧化还原反应中储存电荷，Mn 3 +/4+在LiMn 2 O 4中的存在，这限制了锂离子电池的能量存储。诸如Li[Li0.2Ni0.2Mn0.6]O-2的化合物表现出储存超过过渡金属氧化还原反应的电荷的能力。额外的容量发生在4.5V和4.5V以上（相对于Li+/Li）。在4.5 V下的容量由O-2（-）阴离子的氧化主导，占类似于0.43 e（-）/分子式单位，另外的0.06 e（-）/分子式单位与晶格中的O损失有关。相比之下，4.5 V以上的容量主要是O损失，类似于0.08 e（-）/公式。O的氧化还原反应涉及在充电期间在O上形成局域空穴态，其位于O上由（Mn 4 +/Li+）配位。结合180标记的Li[Li_（0.2）Ni_（0.2）Mn_（0.6）]O_（2-）的操作电化学质谱、XANES、软X射线光谱、共振非弹性X射线光谱和拉曼光谱得到了这些结果。最后，O的氧化还原的一般特点进行了描述与讨论的作用，相对离子（共价键较少）的3d金属氧相互作用的阴离子氧化还原在富锂正极材料。
Conventional intercalation cathodes for lithium batteries store charge in redox reactions associated with the transition metal cations, e.g., Mn3+/4+ in LiMn2O4, and this limits the energy storage of Li-ion batteries. Compounds such as Li[Li0.2Ni0.2Mn0.6]O-2 exhibit a capacity to store charge in excess of the transition metal redox reactions. The additional capacity occurs at and above 4.5 V versus Li+/Li. The capacity at 4.5 V is dominated by oxidation of the O-2(-) anions accounting for similar to 0.43 e(-)/formula unit, with an additional 0.06 e(-)/formula unit being associated with O loss from the lattice. In contrast, the capacity above 4.5 V is mainly O loss, similar to 0.08 e(-)/formula. The O redox reaction involves the formation of localized hole states on O during charge, which are located on O coordinated by (Mn4+/Li+). The results have been obtained by combining operando electrochemical mass spec on 180 labeled Li[Li0.2Ni0.2Mn0.6]O-2 with XANES, soft X-ray spectroscopy, resonant inelastic X-ray spectroscopy, and Raman spectroscopy. Finally the general features of O redox are described with discussion about the role of comparatively ionic (less covalent) 3d metal oxygen interaction on anion redox in lithium rich cathode materials.