Stable colloid-in-acid electrolytes for long life proton batteries. (November 2022)

• Record Type: Journal Article
• Authors: Guo, Haocheng; Wan, Liyang; Tang, Jiaqi; Wu, Sicheng; Su, Zhen; Sharma, Neeraj; Fang, Yu; Liu, Zhaoping; Zhao, Chuan
• Is Part Of: Nano energy. Volume 102(2022)
• Publication Date: 2022-11
• Subjects: Aqueous batteries -- Colloid -- Electrolysis -- Proton -- MnO2; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2022.107642
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: The emerging proton electrochemistry offers opportunities for future energy storage of high capacity and rate. However, the development of proton batteries is hindered by low working-potentials of electrodes and poor cycle life of full-cells (e.g., tens-of-hours). The high-potential MnO2 /Mn 2+ redox couple presents a facile and competitive cathode choice, typically via electrodepositing solids on substrates for energy storage. Herein, we show the formation of homogeneous and stable MnO2 colloids from the Mn 2+ electrolysis in H2 SO4 (≥ 1.0 M), and their application to achieve long life proton batteries. Colloid electrolytes enable prolonged cycling of a MnO2 //MoO3 cell from 11.7 h to 33 days, and a MnO2 //pyrene-4, 5, 9, 10-tetraone cell for 489days, which is the longest duration ever reported for proton batteries. Comprehensive analysis shows the colloid particle is mainly a MnO2 nucleus coordinated by electrolyte ions of hydrated Mn 2+, Mn 3+, H + and SO4 2- . Through water dilution, solid components of colloids precipitate into hierarchical nanosheet spheres; Further characterizations of the precipitates and deposited substrates reveal ε-MnO2 as the major electrolytic product regardless of electrolytes used. Different colloids could reform from precipitates depending on presence/absence of Mn 2+ in acids, suggesting colloid balances include both physical and chemical interactions. Our findings of the new chemistry for the MnO2 /Mn 2+ electrolysis are also anticipated to underlie a range of novel aqueous energy storage. Graphical Abstract: Electrolysis of MnO2 /Mn 2+ redox couple is understood as simple solid electrodeposition on substrates, and attracts attentions in aqueous energy storage recently. Herein, a new chemistry is demonstrated to additionally form homogeneous and stable colloids in H2 SO4 (≥ 1.0 M). Application of colloid electrolytes in the emerging proton batteries results in significantly extended battery cycle life from tens-of-hours to months. ga1 Highlights: Mn 2+ electrolysis is demonstrated to form homogeneous and stable MnO2 colloids in acids. Colloid electrolytes significantly prolong proton battery cycle life from just tens-of-hours to months. Properties, components, and their interactions of the MnO2 colloids are disclosed via comprehensive analysis.