A journey through layered cathode materials for lithium ion cells – From lithium cobalt oxide to lithium-rich transition metal oxides

Lithium ion batteries (LIBs) have emerged as an important power source for various applications including portable electronics, military, space etc. Cathode materials play an important role in deciding the performance of LIBs. Layered transition metal oxides have drawn much attention for application as cathode material in LIBs due to their high specific capacities, high energy densities and good cycle life. LiCoO2, LiNi0.8Co0.15Al0.05O2 and LiMnxNiyCozO2 are the commonly used layered cathode materials in LIBs. In the past two decades, intensive efforts have been made to develop cathode materials with much higher energy densities for meeting the requirements for modern applications. However, several issues and challenges such as their dubious crystal structure, uncertain reaction mechanism, high initial irreversible capacity, fast voltage fading, poor cycle life and poor rate capability must be resolved before they are employed for realistic commercial applications. This review gives an overview of the different layered cathode materials for LIBs starting from the first generation cathode material, LiCoO2 to the latest Li-rich layered cathode materials. The effect of cathode structure, morphology, role of transition metals and doping of different metal ions on the performance of LIBs are discussed.