Battery performance intercalation compounds

These ionic conductors could probably not be used as solid electrolytes in operating batteries because when brought into contact with lithium or sodium they would lead to true intercalation compounds AyNa, MiMi., 82 (y 1 — x) with an electronic contribution. However, they provide models for studying ionic mobility in a truly two-dimensional space. The absence of electronic conductivity allows complex impedance measurements and not only NMR studies to be performed. 

In this case a potassium-graphite (KCg) electrode has been used as the carbonaceous anode material. Upon anodic polarisation this electrode irreversibly deintercalates potassimn resulting in a graphite-like compound, which on subsequent cycles performs with fast kinetics of its lithium intercalation-deintercalation process [89, 90]. Accordingly, the first charging process of the battery may be written as shown in Equation 7.7 at the anode. 

However, during efforts to develop rechargeable Mg batteries in recent years, it was realized that the selection of materials suitable for the Mg ion insertion presents a great challenge. In fact, in spite of the expected similarity between Li and Mg ion intercalation, almost all inorganic compounds, which prove themselves as suitable cathode materials for Li batteries, show very poor electrochemical performance regarding Mg ion insertion. 

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