Solid-State Chemistry and Electrochemistry of LiCo1 ∕ 3Ni1 ∕ 3Mn1 ∕ 3O2 for Advanced Lithium-Ion Batteries: III. Rechargeable Capacity and Cycleability

Abstract

Reaction mechanism of was examined by ex situ X-ray diffraction (XRD) and electrochemical methods. According to XRD results, the change in hexagonal lattice parameters was quite similar to that of , i.e., the unit cell volume was almost constant at in , indicating homogeneous phase reaction over an entire range. Reversible-potential measurements on against a lithium electrode were also carried out and the solid-state redox reactions were described by applying the concept of electrochemical density of states (EDS). Gibbs free-energy change for the reaction of was obtained to be , which was slightly higher than that for . Rechargeable capacity as a function of charge-end voltage was examined for cells and the relation between in and in V was given to be . From these results, rechargeable capacity and cycleability as a function of charge-end voltage are discussed in relation to the reaction mechanism of .