Discharging Behavior of Hollandite α-MnO2 in a Hydrated Zinc-Ion Battery

Thanh Le; Nahian Sadique; Lisa M Housel; Altug S Poyraz; Esther S Takeuchi; Kenneth J Takeuchi; Amy C Marschilok; Ping Liu

doi:10.1021/acsami.1c18849

Discharging Behavior of Hollandite α-MnO₂ in a Hydrated Zinc-Ion Battery

ACS Appl Mater Interfaces. 2021 Dec 22;13(50):59937-59949. doi: 10.1021/acsami.1c18849. Epub 2021 Dec 13.

Authors

Thanh Le¹, Nahian Sadique^{1

2}, Lisa M Housel^{2

3}, Altug S Poyraz⁴, Esther S Takeuchi^{1

2

3

5}, Kenneth J Takeuchi^{1

2

3

5}, Amy C Marschilok^{1

2

3

5}, Ping Liu^{1

6}

Affiliations

¹ Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794, United States.
² Institute for Electrochemically Stored Energy, State University of New York at Stony Brook, Stony Brook, New York 11794, United States.
³ Interdisciplinary Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States.
⁴ Department of Chemistry, Kennesaw State University, Kennesaw, Georgia 30144, United States.
⁵ Department of Materials Science and Chemical Engineering, State University of New York at Stony Brook, Stony Brook, New York 11794, United States.
⁶ Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, United States.

PMID: 34898172
DOI: 10.1021/acsami.1c18849

Abstract

Hollandite, α-MnO₂, is of interest as a prospective cathode material for hydrated zinc-ion batteries (ZIBs); however, the mechanistic understanding of the discharge process remains limited. Herein, a systematic study on the initial discharge of an α-MnO₂ cathode under a hydrated environment was reported using density functional theory (DFT) in combination with complementary experiments, where the DFT predictions well described the experimental measurements on discharge voltages and manganese oxidation states. According to the DFT calculations, both protons (H⁺) and zinc ions (Zn²⁺) contribute to the discharging potentials of α-MnO₂ observed experimentally, where the presence of water plays an essential role during the process. This study provides valuable insights into the mechanistic understanding of the discharge of α-MnO₂ in hydrated ZIBs, emphasizing the crucial interplay among the H₂O molecules, the intercalated Zn²⁺ or H⁺ ions, and the Mn⁴⁺ ions on the tunnel wall to enhance the stability of discharged states and, thus, the electrochemical performances in hydrated ZIBs.

Keywords: discharge of proton/zinc; hollandite α-MnO2; hydration; zinc-ion batteries.