Abstract:

The todorokite manganese oxides were widely examined as lithium insertion hosts for cathodes in rechargeable lithium batteries, catalytic materials, adsorbents, etc. Cu²⁺ doped todorokites also showed potential as electro-catalytic materials with selectivity. In this paper, the single and Cu²⁺ ion doped todorokites were prepared with different processes, and the influences of reaction conditions on product purity were investigated. The electrochemical activity and stability of todorokites were studied by powder microelectrode. It was found that the single todorokite or with Cu²⁺ doping on structure could be formed at atmosphere pressure by a refluxing process. The Cu²⁺ ion doped todorokite in the tunnel could only be synthesized in autoclave at a relative high temperature and pressure, and reaction temperature was the main influential factor for synthesis of single phase materials in the process. Todorokites exhibited high electrochemical activity and stability in solutions with high pH value. Cu²⁺ ion doping on structure would enhance the electrochemical activity and stability of todorokite, but it had a negative effect for electrochemical characters with Cu²⁺ ion doping in the tunnel. The structure of todorokite with Cu²⁺ doping in the tunnel was further proved by cyclic voltammetry with help of powder microelectrode.

Key words: Todorokite; Dope; Synthesis; Powder microelectrode; Cyclic voltammetry