Development of MnO 2 Based Cathodes for Alkaline Batteries via Combinatorial Approach

Abstract

A combinatorial study is carried out to develop new cathode compositions in alkaline Zn-MnO 2 secondary batteries. MnO 2 is modified with ternary additions using Bi 2 O 3 , Na 0.7 MnO 2, and NiO. A library of thick film cathodes over a wide compositional range is synthesized via sputter deposition. Thick film cathodes are investigated both electrochemically and structurally. Structural studies show that thick film cathodes are largely amorphous in the as-deposited state but upon charge-discharge cycling, are crystallized into δ -MnO 2, i.e. layered polymorph of MnO 2 . The thick film cathodes are evaluated with cyclic voltammetry and charge-discharge cycling. Two compositional regions are noted as significant in terms of useful cathodes for rechargeable batteries. Compositions rich in NiO yield quite a reliable cell performance which might be considered as cathode material for Zn-NiO batteries. More importantly, there was also a region where Mn and Na had similar proportions doped by Bi and Ni, e.g. Bi 0.08 Na 0.39 Ni 0.09 Mn 0.44 O x , which might be made the basis for improved cathode for Zn-MnO 2 batteries.