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DOE OSTI · 2997748

Dynamics of disordered intermediates during the two-electron alkaline MnO 2 conversion reaction for grid-scale batteries

Zimmerer, Eric K. [Northeastern Univ., Boston, MA (United States)]·Liang, Wentao [Northeastern Univ., Burlington, MA (United States)]·Somaskandan, Rachana [Northeastern Univ., Boston, MA (United States)]·DeToma, Elizabeth [Northeastern Univ., Boston, MA (United States)]·Fawcett, Connor [Northeastern Univ., Boston, MA (United States)]·Bruck, Andrea M. [Northeastern Univ., Boston, MA (United States)]·Ma, Lu [Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)] (ORCID:0000000196460738)·Ehrlich, Steven N. [Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)]·Zhao, Qing [Northeastern Univ., Boston, MA (United States)]·Gallaway, Joshua W. [Northeastern Univ., Boston, MA (United States)] (ORCID:0000000267987781)
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Abstract

Battery technologies beyond Li-ion are likely needed for extensive integration of grid-scale storage. The rechargeable Zn-MnO 2 chemistry has the potential for high sustainability, high safety, and low cost, using Earth-abundant basis materials. In an alkaline electrolyte, the MnO 2 cathode can cycle reversibly if modified by including a Bi-containing additive, although the cycling mechanism remains mostly unknown. This work presents an account of the intermediate species involved in the electrochemical transformation from layered δ-MnO 2 to Mn(OH) 2 and back. During charge, a disordered intermediate with a structure resembling layered β-MnOOH exists stably for an extended period, corresponding to a regime known to have unexpected electrochemical activity of Bi. During discharge, β-MnOOH exists only briefly and is never the majority material, revealing that the cycling mechanism is asymmetric. In conclusion, these findings represent a significant advance in mechanistic knowledge and can enable engineering to develop the system for commercial use.

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36 MATERIALS SCIENCEEXAFSMnO 2alkaline batteryelectrochemistryextended X-ray absorption fine structureoperando

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Zimmerer, Eric K. [Northeastern Univ., Boston, MA (United States)], Liang, Wentao [Northeastern Univ., Burlington, MA (United States)], Somaskandan, Rachana [Northeastern Univ., Boston, MA (United States)], DeToma, Elizabeth [Northeastern Univ., Boston, MA (United States)], Fawcett, Connor [Northeastern Univ., Boston, MA (United States)], Bruck, Andrea M. [Northeastern Univ., Boston, MA (United States)], Ma, Lu [Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)] (ORCID:0000000196460738), Ehrlich, Steven N. [Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)], Zhao, Qing [Northeastern Univ., Boston, MA (United States)], Gallaway, Joshua W. [Northeastern Univ., Boston, MA (United States)] (ORCID:0000000267987781). 2025-08-08. Dynamics of disordered intermediates during the two-electron alkaline MnO 2 conversion reaction for grid-scale batteries. https://doi.org/10.1016/j.joule.2025.102090

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DOE OSTI2026

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The transition to a flexible and reliable energy infrastructure, using electro-thermal energy generation technologies such as geothermal, concentrated solar power, and nuclear, usually demands simultaneous advancement of thermal energy storage (TES) to support on-demand electricity generation and industrial applications while mitigating the inherent intermittency of renewable energy sources and power outages from direct energy generation. Among TES technologies, thermochemical energy storage (TCES) based on calcium looping emerges as a compelling high-power energy storage candidate due to its high reaction enthalpy, compatibility with elevated operating temperatures, and abundance of low-cost materials. However, the long-term durability of calcium-based sorbents for TCES is hindered by surface sintering and particle aggregation, leading to performance degradation over repeated thermal cycles. This study explores a moisture hydration-based strategy to regenerate a degraded calcium sorbent and mitigate performance degradation for long duration TCES. The addition of moisture transforms calcium oxide into calcium hydroxide and produces intercalation water layers, associated with a regenerated surface area and reduced calcium oxide crystallite size. Both these effects are beneficial in restoring the sorbents' reactivity for carbonization. Additionally, an optimized hydration-assisted reactivation protocol balances the recovered energy storage capacity with heating penalty required for moisture removal from hydrated samples, resulting in an enhanced energy storage capacity up to 176% compared to benchmark sorbents that undergo cycling without reactivation after 60 cycles. In conclusion, these results highlight the potential of hydration-assisted reactivation to enhance the long-term performance of TCES, providing an effective pathway to advancing electro-thermal storage technologies.

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