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Abstract: Lithium rich materials xLi₂MnO₃·(1-x)LiMO₂ (0<x<1, M=Mn, Co, Ni) become a hot topic because of their high capacities exceeding 250 mAh·g^-1 and low cost. However, the large irreversible capacity during the first cycle, low rate capability and structure collapse during cycling remain impediments in developing these cathodes for applications. The structure analyses and charge/discharge mechanisms for lithium rich materials are currently main research contents. Although whether the lithium rich materials are solid solutions or composite is still controversial, oxygen release mechanism on the first charge 4.5 V plateau of lithium rich materials has come to consistency. Several modifications, such as bulk doping, surface coating and microstructure control, demonstrate promising strategies to obviously improve electrochemical properties. The structure, charge/discharge mechanism, synthesis methods and electrochemical modifications of lithium rich cathode materials are systematically reviewed in this article. Further research aspects of these kinds of materials as cathode materials for lithium ion batteries are also discussed.

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