The intercalation and hydrothermal chemistry of solid electrodes

Intercalation chemistry plays a key role in the electrochemical reduction and oxidation by lithium of many solid electrodes, including transition metal compounds and graphite. For 25 years, from TiS₂ and graphite to Li_xCoO₂ and LiMn₂O₄, the electrode reactions of such intercalation compounds have been extensively studied. Much emphasis has been placed on two simple classes of structures, layer and spinel, both of which are formed by Li_xTiS₂ and Li_xMnO₂. More recently, much effort has been directed at synthesizing new structures that might show enhanced electrochemical activity. Soft chemistry approaches have been harnessed for this purpose. Mild hydrothermal reactions are one such approach. Several new vanadium oxides have been formed, as well as layered forms of manganese oxide. A number of these new compounds reversibly react with lithium and therefore may be used as the cathode in lithium batteries.