Manganese oxide is a popular energy storage material, which features good capacity, earth abundance, low toxicity, and low cost. There are also numerous methods for synthesizing different types of manganese oxide for use in energy storage devices. While electrical conductivity and crystal structure, are relatively easy to determine, very little has been done to understand the porous character of MnO2 and how it influences transport of metal ions inside and through the material. There is also ongoing uncertainty as to the mechanism of energy storage in MnO2 based materials, particularly in respect to the contribution of lithium or other metal cations as opposed to protons. We use ion current through a single manganese oxide rod deposited in a single pore as a probe of the geometrical and electrochemical properties of the material. This method takes advantage of the properties of the electrochemical double layer, and has been applied to polymer nanopores and biological channels before. The recorded current confirmed a porous character of the MnO2 structure, probed the effective size of the mesh voids, and the presence as well as polarity of surface charges. The recorded ion current through deposited MnO2 structure was not significantly influenced by the presence of protons.

Probing porous structure of electrode materials with ionic current

247th National Meeting (2014)

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