Jump to main content
Jump to site search

Issue 32, 2017
Previous Article Next Article

Synthesis of cryptomelane type α-MnO2 (KxMn8O16) cathode materials with tunable K+ content: the role of tunnel cation concentration on electrochemistry

Author affiliations

Abstract

The role of tunnel cations in the electrochemistry of α-MnO2 materials has been long discussed and demands investigation as the electrochemistry of α-MnO2 materials is strongly dependent on the material specific properties (i.e. morphology, surface area, crystallite size, and chemical composition). Here, we systematically synthesized a series of α-MnO2 samples with differing K+ content but similar physicochemical and morphological properties allowing direct investigation of the role of tunnel cation (K+) on the lithium ion electrochemistry of α-MnO2 cathodes. The nanofibrous α-MnO2 materials have a chemical composition of KxMn8O16·yH2O, where 0 ≤ x ≤ 0.75 and 0.53 ≤ y ≤ 0.81. The α-MnO2 materials have similar morphology, crystallite size (17–19 nm), surface area (66–76 m2 g−1), and tunnel water content (0.53–0.81). The electrochemistry of the α-MnO2 materials was evaluated using cyclic voltammetry, galvanostatic cycling, and galvanostatic intermittent titration type tests. The α-MnO2 materials with 0 to 0.32 K+ content showed discharge curves with higher voltage, higher specific energies, and improved capacity retention compared to the 0.75 K+ containing α-MnO2 material. Fewer structural distortions were observed in lithiated samples with lower K+ content through modelling of X-ray absorption spectroscopy data indicating improved structural stability of those samples which positively impacted the electrochemistry.

Graphical abstract: Synthesis of cryptomelane type α-MnO2 (KxMn8O16) cathode materials with tunable K+ content: the role of tunnel cation concentration on electrochemistry

Back to tab navigation

Supplementary files

Publication details

The article was received on 21 Apr 2017, accepted on 21 Jul 2017 and first published on 21 Jul 2017


Article type: Paper
DOI: 10.1039/C7TA03476H
Citation: J. Mater. Chem. A, 2017,5, 16914-16928
  •   Request permissions

    Synthesis of cryptomelane type α-MnO2 (KxMn8O16) cathode materials with tunable K+ content: the role of tunnel cation concentration on electrochemistry

    A. S. Poyraz, J. Huang, C. J. Pelliccione, X. Tong, S. Cheng, L. Wu, Y. Zhu, A. C. Marschilok, K. J. Takeuchi and E. S. Takeuchi, J. Mater. Chem. A, 2017, 5, 16914
    DOI: 10.1039/C7TA03476H

Search articles by author

Spotlight

Advertisements