Electronic structure 'engineering' in the development of materials for Li-ion and Na-ion batteries*

Janina Molenda

Abstract

Transition metal oxides with a general formula A _x M _a O _b (A  =  Li, Na, M  =  transition metal) constitute a group of potential electrode materials for a new generation of alkaline batteries. This application is related to the fact that these compounds can reversibly intercalate high amounts of alkaline ions (1 or more moles per mole of M _a O _b ) already at room temperature, without significant changes in their crystallographic structure. The author of this work basing on her own investigations of A _x M _a O _b (A  =  Li, Na; M  =  3d, 4d, 5d) has demonstrated that the electronic structure of these materials plays an important role in the intercalation process. Electronic model of intercalation process is presented. Author's studies show that electronic structure 'engineering' is an excellent method of controlling properties of the cathode materials for Li-ion and Na-ion batteries, changing their unfavorable character of the discharge curve, from step-like to monotonic, through modification and control density of states function of a cathode material