Effects of electrolyte doping on electrodeposited nanostructured manganese oxide and chromium oxide

Abstract

Electrolyte additions are used to control the functionality of a nanostructured oxide. Dopant ions affect the size and shape of deposit crystallites and modify the host structure. Such ions can be incorporated into the deposit or form a separate oxide phase. The manganese dioxide family of polymorphs with ion-molecular sieve properties represents the additional possibilities of “template” effects of dopant ions on the phase composition, heterovalent substitution in the cationic sublattice, changes in morphology and alteration of nanocrystallite size during electrocrystallisation. The effects of electrolyte doping in electrodeposited, non-stoichiometric manganese dioxide (NH4+, Li+ and Co2+), chromium oxide-based films (Co2+, Li+) were investigated. The structural characteristics and morphology were studied for all the obtained nanocomposites and deposits were evaluated as highly crystalline cathode materials cathodes, having high cyclability, in Li batteries. The improved functionality of the electrodeposited nanomaterials was correlated to structural changes. Hollandite and pyrolusite electrodeposition pathways were proposed, based on symmetry principles of phase transitions.