High Li storage capacity of poorly crystalline porous δ-MnO 2 prepared by hydrothermal route

Prasant Kumar Nayak, Tirupathi Rao Penki, N. Munichandraiah

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9 Scopus citations


Poorly crystalline porous δ-MnO2 is synthesized by hydrothermal route from a neutral aqueous solution of KMnO4 at 180 C and the reaction time of 24 h. The as-synthesized sample and also the sample heated at 300 C have nanopetals morphology with large surface area. On heating at temperatures ≥400 C, there is a decrease in BET surface area and also a change in morphology from nanopetals to clusters of nanorods. Furthermore, the poorly crystalline δ-MnO2 converts into well crystalline α-MnO2 phase. The electrochemical lithium intercalation and de-intercalation studies in a non-aqueous electrolyte provide a high discharge specific capacity (275 mAh g-1) at a specific current of 40 mA g -1 for the poorly crystalline δ-MnO2 samples. The rate capability is also high. There is a decrease in capacity on repeated charge-discharge cycling. The specific capacity values of the crystalline α-MnO2 samples are considerably less than the values of poorly crystalline δ-MnO2 samples. Thus, the hydrothermal route facilitates preparation of poorly crystalline electrochemically active porous MnO2.

Original languageEnglish
Pages (from-to)126-134
Number of pages9
JournalJournal of Electroanalytical Chemistry
StatePublished - 2013
Externally publishedYes


  • Cathode material
  • High capacity
  • Morphology
  • Poor crystallinity
  • Porous manganese dioxide


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