Li-Rich Layer-Structured Cathode Materials for Li-Ion Batteries

Electrode materials are important building blocks of lithium ion batteries. The capacity of the anode material is usually more than 300 mAh/g while that of the cathode is still around 150 mAh/g. The capacity of the cathode materials has become a bottleneck to the improvement of the electrochemical performances of lithium ion battery. Li-rich layer-structured Li(1+x)A(1-x)O(2) (A = Mn, Ni, Co, Ti, Zr, etc.) cathode materials caught the attention of the scientists in the past decade due to high reversible capacity (200 mAh/g or more). These materials can also be written as xLi(2)MO(3) center dot (1 - x)LiM'O(2) (M = Mn, Ti, Zr; M' = Mn, Ni, Co; 0 <= x <= 1). In this review, we introduce the synthesis methods, structure and the charge-discharge mechanism of this type of materials. More attention will be paid to the improvement to their electrochemical properties by surface (coating) and bulk (doping) modification. At the end of this review, the problems and prospects of the research on these cathode materials are commented.