gamma-MnO2 for Li batteries Part I. gamma-MnO2: Relationships between synthesis conditions, material characteristics and performances in lithium batteries

With the use of various electrodeposition conditions (concentration and pH of the bulb MnSO4 solution, temperature, synthetic mode) and thermal treatm ents, gamma-MnO2 materials exhibiting rather different physico-chemical and structural characteristics were prepared. Relationships were established b etween synthesis conditions and such characteristics, showing that to some extent, these physico-chemical and structural parameters can be tuned. The electrochemical behavior of lithiated phases obtained upon the first Li ins ertion into these gamma-MnO2 materials has been investigated. It is shown t hat the maximum Li reversible intercalation capacity strongly depends on th e structural parameters (concentration of De Wolff defects and degree of mi crotwinning) of the starting gamma-MnO2 samples. (C) 1999 Elsevier Science S.A. All rights reserved.