Electrode Materials with the Na_0.44MnO₂ Structure: Effect of Titanium Substitution on Physical and Electrochemical Properties

The physical and electrochemical properties of Li x MnO 2 and Li x Ti 0.11 Mn 0.89 O 2 synthesized from precursors made by glycine−nitrate combustion (GNC) and solid-state synthesis methods (SS) are examined in this paper. The highest specific capacities in lithium cells are obtained for SS-Li x MnO 2 electrodes at low current densities, but GNC-Li x Ti 0.11 Mn 0.89 O 2 electrodes show the best high-rate performance. These results can be explained by changes in the voltage characteristics and differences in the particle morphologies induced by the Ti-substitution and synthesis method. Ti-substitution also results in a decrease in the electronic conductivity but greatly improves the thermal properties and imparts dissolution resistance to the electrode. For these reasons, it is preferable to use Li x Ti 0.11 MnO 0.89 O 2 in lithium battery configurations rather than Li x MnO 2 . Suggestions for improving the electrochemical performance of the Ti-substituted variant are given based on the results described herein.