Simple and Cost-Effective Approach to Dramatically Enhance the Durability and Capability of a Layered δ-MnO2 Based Electrode for Pseudocapacitors: A Practical Electrochemical Test and Mechanistic Revealing

Minghai Yao, Xu Ji, Tsung Fu Chou, Shuang Cheng, Lufeng Yang, Peng Wu, Haowei Luo, Yuanyuan Zhu, Lujie Tang, Jenghan Wang, Meilin Liu

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3 Citations (Scopus)


Inadequate capacity and poor durability of MnO2 based pseudocapacitive electrodes have long been stumbling blocks in the way of their commercial use. Though layered δ-MnO2 has higher potential to be used due to its proton-free energy storage reactions, its durability is still far away from carbon based electrodes associated with structure deformation caused by interlayer spacing change and Jahn-Teller effect. Here we report an effective approach to dramatically enhance not only the stability but also the capacity of δ-MnO2 based electrode through a simple incorporation of exotic cations, hydrated Zn2+, in the tunnel of the material. Even at a very fast charge/discharge rate (50 A g-1), the capacity of the electrode is gradually increased from 268 to 348 F g-1 after ∼3,000 cycles and then remains relatively constant in the subsequent ∼17,000 cycles, which means ∼128% of the initial capacity is maintained after 20,000 cycles. In contrast, the capacity of bare δ-MnO2 electrode without modification is degraded gradually along the cycling, retaining only ∼74% of the initial value after 20,000 cycles. To reveal the basic chemistry between them, synchrotron X-ray diffraction and Raman spectroscopy were performed to explore the structural evolution of the modified δ-MnO2 during cycling; DFT computation was used to estimate the energetics and vibration modes associated with the hydrated Zn2+. The performance enhancement is attributed largely to the preaccommodation of [Zn (H2O)n]2+, which effectively suppresses the interlayer spacing change during cycling and thus benefits the stability.

Original languageEnglish
Pages (from-to)2743-2750
Number of pages8
JournalACS Applied Energy Materials
Issue number4
Publication statusPublished - 2019 Apr 22



  • DFT computation
  • in situ Raman
  • layered δ-MnO/NaMnO
  • pseudocapacitor
  • tunnel structure modification/preaccommodation of exotic ions

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Energy Engineering and Power Technology
  • Electrochemistry
  • Materials Chemistry
  • Electrical and Electronic Engineering

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