非原位拉曼光谱区分富锂层状氧化物的集成结构:一种预测Li2MnO3活化程度的有效方法

Differentiating the Integrated Structure from Lithium Rich Layer Oxide by ex situ Raman Spectroscopy: an Effective Method to Predict the Activation of Li_2MnO_3

采用5种方法,即溶胶-凝胶法、高温固相法、共沉淀法、水热法和溶剂热法合成了富锂材料Li_(1.2)Mn_(0.6)Ni_(0.2)O_2。拉曼光谱研究发现共沉淀法制备的样品是固溶体结构,而其他4个样品是以不同尺度共生形成的复合物结构。电化学性能测试结果表明这5个富锂材料性能存在明显差异,尤其是在首次充电过程中5个样品位于4.5 V以上由Li_2MnO_3组分活化所贡献的容量明显不同,共沉淀法制备的具有固溶体结构的样品中由Li_2MnO_3组分活化贡献的容量最多。由此我们建立起电化学性能与两相集成方式的联系,不同的集成方式使得Li_2MnO_3组分活化所贡献的容量不同,进而影响了最终的电化学性能。

The L i1.2Mn0.6N i0.2 O2 cathode was prepared b]five synthesis routes:sol-gel,high temperature solid,coprecipitation,hydrothermal and solvothermal method.The analysis of Raman spectrum shows that the coprecipitation sample is solid solution structure,while the other four samples are composite structures formed at different scales.The results of electrochemical tests for as-prepared samples show obviously different performance,especially the capacity from the activation of Li2MnO3 during the first charging process(>4.5 V).The co-precipitation sample with solid solution structure shows the highest capacity from the activation of L i2MnO3.Therefore,we can establish the connection between electrochemical performance and two-phase integration modes.Different integration modes affect the activation capacity of L i2MnO3,leading to different electrochemical properties.