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.
Herein, positive electrodes were calendered from a porosity of 44–18% to cover a wide range of electrode microstructures in state-of-the-art lithium-ion batteries.
Lithium metal was used as a negative electrode in LiClO 4, LiBF 4, LiBr, LiI, or LiAlCl 4 dissolved in organic solvents. Positive-electrode materials were found by trial-and-error investigations of organic and inorganic materials in the 1960s.
Lithium-ion batteries consist of two lithium insertion materials, one for the negative electrode and a different one for the positive electrode in an electrochemical cell. Fig. 1 depicts the concept of cell operation in a simple manner . This combination of two lithium insertion materials gives the basic function of lithium-ion batteries.
The cathode materials of lithium batteries have a strong oxidative power in the charged state as expected from their electrode potential. Then, charged cathode materials may be able to cause the oxidation of solvent or self-decomposition with the oxygen evolution. Finally, these properties highly relate to the battery safety.
The anode and cathode electrodes play a crucial role in temporarily binding and releasing lithium ions, and their chemical characteristics and compositions significantly impact the properties of a lithium-ion cell, including energy density and capacity, among others.