Issue 29, 2022

Electrochemistry of rechargeable aqueous zinc/zinc-sulphate/manganese-oxide batteries and methods for preparation of high-performance cathodes

Abstract

Rechargeable aqueous Zn/ZnSO4/MnO2 batteries, due to their high performance and safety, have attracted much attention as promising candidates for grid-scale energy storage. Despite intensive efforts in previous studies, the cathode electrochemistry remains largely unidentified. We observed new insights into the cathode electrochemistry in Zn/ZnSO4/MnO2 batteries and found that, regardless of the physicochemical states of manganese in the pristine, as-prepared cathode, birnessite is the fated compound. The birnessite consisted of both Mn(III) and Mn(IV) with Zn2+ as the foreign cation. Birnessite stores energy via chemical redox reactions. Mn(III) has the highest priority for discharge. Mn(IV) discharges stepwise, first to MnO–OH, and then MnO–OH continuously discharges to Mn2+. During recharge, birnessite is produced stepwise via Mn2+ → MnO–OH and MnO–OH → birnessite. Zinc sulphate hydroxide plays essential roles in driving discharge and recharge via its formation with hydroxyl ions (by-products of discharge) and via neutralization of proton ions (by-products of recharge). We inserted birnessite into three-dimensional networks of single-walled carbon nanotubes (3D-SWCNT-networks) via electrochemical deposition and the superior conductive properties of the birnessite/3D-SWCNT-networks have extended the cycling numbers of the rechargeable aqueous Zn/ZnSO4/MnO2 batteries over 11 000 with a capacity retention > 82.5% at a high discharge/recharge rate of 1.5 A g−1. The rechargeable aqueous Zn/ZnSO4/MnO2 batteries with birnessite/3D-SWCNT-networks as cathodes are the promising devices for applications in long-term energy storage.

Graphical abstract: Electrochemistry of rechargeable aqueous zinc/zinc-sulphate/manganese-oxide batteries and methods for preparation of high-performance cathodes

Supplementary files

Article information

Article type
Paper
Submitted
09 May 2022
Accepted
30 Jun 2022
First published
30 Jun 2022

J. Mater. Chem. A, 2022,10, 15415-15426

Electrochemistry of rechargeable aqueous zinc/zinc-sulphate/manganese-oxide batteries and methods for preparation of high-performance cathodes

W. Gong, B. Fugetsu, W. Mao, A. K. Vipin, I. Sakata, L. Su, X. Zhang and M. Endo, J. Mater. Chem. A, 2022, 10, 15415 DOI: 10.1039/D2TA03729G

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