Positive electrodes for Li-ion and lithium batteries (also termed “cathodes”) have been under intense scrutiny since the advent of the Li-ion cell in 1991. This is especially true in the past decade.
This mini-review discusses the recent trends in electrode materials for Li-ion batteries. Elemental doping and coatings have modified many of the commonly used electrode materials, which are used either as anode or cathode materials. This has led to the high diffusivity of Li ions, ionic mobility and conductivity apart from specific capacity.
This paper deals with the advantages and disadvantages of the positive electrodes materials used in Li-ion batteries: layered LiCoO 2 (LCO), LiNi y Mn y Co 1−2y O 2 (NMC), spinel LiMn 2 O 4 (LMO), LiMn 1.5 Ni 0.5 O 4 (LMN) and olivine LiFePO 4 (LFP) materials.
Coating of the electrode can enhance ionic/electronic conductivity and stability of positive electrode materials. Each coating method or material shows its own advantages, disadvantages, and different coating protocols can greatly affect the chemical or physical composition and structures of a coating on electrode materials.
To compare the properties of positive electrode materials with different Ni content, we synthesized the most popular Ni-rich positive electrode materials NMC622 (x = 0.6) as well as the higher Ni content material NMC811 (x = 0.8) and LNO (x = 1).
The most widely used positive electrode materials in current industries are lithiated iron phosphate LiFePO 4 (LFP), lithiated manganese oxide LiMn 2 O 4 (LMO), lithiated cobalt oxide LiCoO 2 (LCO), lithiated mixed oxide LiNi x Mn y Co z O 2 (NMC), such as NMC-111, NMC-523 or NMC-622, and lithiated mixed oxide LiNi a Co b Al c O 2 (NCA) .