Electrochemistry of inorganic nanocrystalline electrode materials for lithium batteries

Abstract
Aditional electrode materials are based on the redox potential difference of the electrode in the course of intercalation/deintercalation reactions. They are generally well-crystalline host compounds either with layered structure such as LiCoO₂ and LiNiO₂, or with tunnel structure like LiMn₂O₄. Nanocrystalline materials are, however, being re-evaluated recently as `nanoscience' advances. The electrochemistry of this kind of materials is much different from that of traditional crystalline ones because of their significant `surface effects'. In connection with that, the nanocrystalline cathode materials are reported to have an enhanced electrochemical activity when the first significative electrochemical step is insertion of Li⁺ ions (discharge process). The "electrochemical grafting" concept will be given as a plausible explanation. As illustrative examples, electrochemical behaviors of nanocrystalline manganese oxydes are presented.