Findings shed light on the mechanisms of zinc passivation, a critical factor affecting the performance of zinc battery systems

Rechargeable alkaline zinc batteries are a promising technology for large-scale stationary energy storage due to their high energy density, as well as their use of abundant and inexpensive raw materials. New research has clarified an underlying mechanism affecting their performance, resolving a long-standing debate and providing the science for designs with improved performance and reliability.

Alkaline zinc batteries show great potential for low-cost energy storage, yet several technical challenges remain to unlock their full commercial potential. Of critical understanding is zinc passivation, where the active surface of the zinc electrode becomes covered by layer of zinc oxide. The layer acts a barrier to normal electrode operation, affecting how well the battery can store and release energy. Specifically, zinc passivation reduces batteries’ discharge rate, contributes to the shape change of the electrode and creates roughened surfaces that create ideal conditions for dendrite growth—all of which affect battery performance.

Establishing a fundamental understanding of the zinc passivation process can help scientists and manufacturers improve battery performance and benefit other industries, such as manufacturing, where zinc coatings and plating are used to protect metal parts from corrosion.

Funded by the DOE Office of Electricity Energy Storage Division, researchers from Sandia National Laboratories, Oak Ridge National Laboratory, and University of Tennessee have shown that the alkaline zinc passivation mechanism is controlled by the electrolyte’s hydroxide concentration. Using a method known as electrochemical quartz crystal microbalance, the team tracked how the mass of zinc electrodes changed when exposed to different concentrations of a potassium hydroxide solution (KOH), commonly used as an electrolyte in alkaline batteries.  Researchers then evaluated and measured the zinc’s electrodeposition, dissolution, and passivation during electrochemical testing where they directly identified and observed reactions’ occurrences, timing, and cause.  

The team observed that the way zinc becomes inactive changes depending on the levels of hydroxide ions (OH-) and zincate in the solution. As the concentration of OH- increases, the process of zinc passivation shifts from one where zinc sticks to the surface to one where it dissolves and forms new materials. They observed that a natural oxide layer forms in all fully saturated solutions, but not in all half-saturated ones. Additionally, the amount of OH- affects how these oxide layers are structured; they become denser as the concentration increases.

The results suggest that different configurations of the zinc alkaline solution require tailored approaches to effectively manage zinc corrosion, the oxide layers, and passivation. The research builds on the team’s prior work to understand how passivation of the zinc electrode occurs in alkaline solutions. 

The findings are relevant to the nascent zinc-alkaline U.S. battery industry, which has potential to support U.S. grid security and reliability. This work is also relevant to zinc-corrosion prevention applications where zinc coatings and plating are often used by industry to protect metal parts from corrosion. The insights gained could help improve the application of zinc for this purpose.

The research was published earlier this year in the Journal of the Electrochemical Societyin the article titled “Alkaline Zinc Passivation Mechanism is Controlled by Hydroxide Concentration” and featured in an invited talk at the annual Beyond Lithium Ion conference. The effort is part of the DOE Office of Electricity’s research and development to strengthen and modernize the national power grid to maintain a reliable, affordable, secure, and resilient electricity delivery  infrastructure.

More information is available in the published paper.

This work was supported by the U.S. Department of Energy, Office of Electricity (OE), Energy Storage Division.

Citation: R. M. Wittman, R. L. Sacci, and T. A. Zawodzinski, “Alkaline Zinc Passivation Mechanism is Controlled by Hydroxide Concentration,” J. Electrochem. Soc., vol. 172, no. 4, pp. 040514, Apr. 2025, doi: 10.1149/1945-7111/adc6c7.

Researchers shared insights from past deployments and R&D to help bridge fundamental research and fielded technologies for grid reliability and reduced consumer energy costs

In a recent presentation at the Electrochemical Society symposium, insights from a decade of vanadium flow battery development were shared, emphasizing the importance of testing at various scales, addressing safety and reliability issues early, and the challenges faced with the commercialization of mixed-acid electrolytes, particularly concerning chlorine gas generation during deployments.

Reed Wittman, a flow battery researcher from Sandia National Laboratories, presented an invited talk at the Spring 2025 Electrochemical Society Meeting titled “(Some) Lessons Learned from Vanadium Flow Batteries.” Drawing from the previous ten years of Vanadium flow battery development, Reed discussed the importance of testing at various scales prior to system deployment, investigating all potential safety and reliability issues at small scales directly, and how small issues in the lab can become large-scale issues for deployments.

Reed also highlighted lessons from the commercialization of batteries that use a mixed-acid electrolyte. Mixed-acid electrolytes were the focus of significant commercialization efforts from around 2015-2021. However, chlorine gas generation during deployments led to significant failure events. These events ended test deployments earlier than planned and inhibited additional deployments. The example illustrated the significance of testing at multiple scales prior to deployment and incorporating lab-scale findings into developing designs and deployments. The talk also covered the origins of the chlorine gas generation and additional findings relevant to future deployments that are the subject of a forthcoming publication.

These insights are crucial for emerging flow batteries, which promise to enhance grid reliability and security while lowering energy costs for consumers amid rising energy demand over the next decade. Flow batteries are designed for large-scale energy storage applications, but transitioning from lab-scale systems to practical deployments presents significant challenges. Sharing lessons learned from past deployments and R&D is essential for maximizing the success of new systems. This talk addressed key issues relevant to the entire flow battery community, from fundamental research to commercial entities developing deployable solutions.

The Electrochemical Society, the leading organization in battery research and development, convened top researchers from around the globe for this event. The invited talk launched a week-long symposium focused on non-Vanadium technologies, setting the stage for discussions on advancements beyond Vanadium in the field.

Learn more on the conference website or via the published research.

This material is based upon work supported by the U.S. Department of Energy, Office of Electricity (OE), Energy Storage Division

Citation: R. M. Wittman and S. Macchi, “Lessons from Vanadium Flow Batteries for Non-Vanadium Flow Batteries,” ECS Meeting Abstracts, vol. MA2025-01, no. I08, 2025, pp. 2367, doi: 10.1149/MA2025-01452367mtgabs.

On February 7, 2025, the IEEE Std 2686-2024 Recommended Practice for Battery Management Systems in Stationary Energy Storage Applications was published. This recommended practice describes battery management fundamentals, including best practices for its design and configuration. It outlines the hardware and software architectures commonly used in battery management and provides a list of battery management functions applicable to different batteries in various applications. Additionally, it offers recommended communication structures and data models that support interoperability and cybersecurity. The result is a comprehensive list of best practices for the design and integration of battery management systems that protect the safety and longevity of batteries in energy storage applications. This work enhances the reliability and security of battery systems while reducing integration costs for batteries on the grid, ultimately leading to lower energy prices and increased resilience of power systems.

IEEE is a standards development organization that publishes technology standards widely used around the world. Sandia researcher David Rosewater has led the standard’s IEEE working group since its formation in 2018 to build consensus across stakeholder groups, which comprised nearly two hundred stakeholders from various industry sectors.

For more information, visit IEEE Standard 2686-2024.

This work was supported by the U.S. Department of Energy, Office of Electricity (OE), Energy Storage Division.

Refined approach for battery arc flash modeling helps to inform appropriate safety controls for battery systems’ installation and maintenance

When battery systems are installed or serviced, workers must take precautions to work safely with the systems’ equipment and electricity. These safeguards, which include following specified procedures and wearing personal protective equipment, are typically outlined in standards derived from the system’s design and engineers’ assessment of electrical risk.

At the 2025 IEEE IAS Electrical Safety Workshop, Sandia researcher David Rosewater presented a new model to more accurately model arc flash, an infrequent but severe hazard faced by electrical workers. The paper, titled “Practical Battery Arc Flash Models,” provides a physics-informed, empirical model that accounts for the primary reason traditional modeling methods are so inaccurate: the arc’s duration. By incorporating the critical factor of arc duration, the resulting model can more precisely and practically estimate the likelihood and severity of an arc flash. The resulting estimates can then be used to help assess the risk of arc flash with better accuracy than existing methods.

Accurate risk assessments help establish which safety controls and safeguards are necessary and advisable without becoming overly prescriptive or burdensome. By refining the calculations used for battery arc flash modeling, the research informs safety standards applied to battery work, such as NFPA 70E, supporting systems’ safety and cost-effective deployment in the United States and around the globe.

Released as an open-source tool for ease of use, the new method combines cutting-edge research conducted at the national labs with industry expertise. It uses advanced physics, reapplies mathematical models originally developed for stockbrokers to estimate ‘value-at-risk’, and leverages recently published battery arc flash data. Feedback from workshop attendees praised the approach for its focus on data and applicability.

Since 1991, the IEEE IAS Electrical Safety Workshop has provided a forum to enable and accelerate change in the electrical safety culture to prevent workplace injuries from electrical hazards. Because of the Society’s presentation-first policy for contributing authors, the Electrical Safety Workshop is considered a premier forum for electrical safety research.

To learn more, read the paper “Practical Battery Arc Flash Models,” accessible in the workshop’s proceedings.

This material is based upon work supported by the U.S. Department of Energy, Office of Electricity (OE), Energy Storage Division.

On March 26-27, 2025, Sandia technical systems analyst Will McNamara was featured as a keynote speaker at the 2025 USA Energy Storage Summit held in Dallas, TX. The presentation, entitled “A New Era for Long-Duration Technologies,” provided an overview of existing policies and regulations for long-duration technologies and their commercial use cases. McNamara also participated as a panelist in a session titled “Assessing the Market Use-Case for Long Duration Energy Storage,” moderated by Julie Thompson, Vice President of Origination, Commercial & Industrial at Hydrostor, which included fellow panelists from Energy Dome, Echogen, Invinity, and e-zinc.

The Energy Storage Summit includes sessions covering market projections, innovative business models, regulatory impacts, and the integration of renewable energy sources. The annual event focuses on enhancing grid reliability and security through advanced storage solutions. The summit consistently attracts C-Level executives, senior management, project managers, consultants, and key industry stakeholders from across the entire energy storage ecosystem.

The keynote presentation and panel discussion provided an opportunity for McNamara to discuss the progress that the LDES National Consortium has made over the last year contributing to the development of commercialization pathways for emerging energy storage technologies. Additionally, the discussion articulated focused areas of work required to reach DOE goals associated with energy storage and support DOE research and innovation priorities.

For more information, please contact Will McNamara or visit Energy Storage Summit USA.

This work was supported by the U.S. Department of Energy, Office of Electricity (OE), Energy Storage Division.

On March 7, 2025, Sandia researcher David Rosewater was awarded the IEEE IAS Electrical Safety Committee’s Young Professional Achievement Award at the 2025 IEEE Electrical Safety Workshop in Jacksonville, FL, USA. At this conference, Rosewater presented his latest research on practical battery arc flash models, which has the potential to greatly impact battery electrical safety by addressing a long-standing problem.

The Young Professional Achievement Award recognizes individuals who demonstrate outstanding service, dedication, implementation, or promotion of electrical safety within their organizations or through contributions to the IEEE IAS Electrical Safety Committee objectives. Rosewater’s research to advance battery worker safety, his contributions to electrical safety standards, and his work to develop a battery safety training class at Sandia National Laboratories were all highlighted during the awards ceremony. This award acknowledges the tremendous impact of Rosewater’s efforts to advance electrical safety.

Rosewater’s latest research on practical battery arc flash models represents a significant milestone in battery worker safety. Arc flash occurs when a battery is short-circuited, causing an arc of electricity to pass through the air near a worker, potentially resulting in severe burns and other injuries. The most widely used method to calculate the energy in the arc has been found to overestimate the hazard faced by battery workers by an average of 12 calories per square centimeter (cal/cm²) across over 200 published battery arc flash experiments. This discrepancy can mean the difference between simply wearing non-flammable clothing and safety glasses versus donning a full-body protective suit with a hood that reduces visibility, manual dexterity, and accelerates heat exhaustion. The proposed model reduces the average estimation error by 90%, bringing it down to only 1.2 cal/cm². This more accurate model for battery arc flash hazard will prevent the overprescription of protective equipment while ensuring worker safety and reducing labor costs associated with battery installation, maintenance, and removal.

The IEEE Electrical Safety Workshop is the primary technical conference for electrical safety worldwide. Research presented at the workshop has commonly led to changes in international electrical safety standards such as NFPA 70E and CSA Z462.

This work was supported by the U.S. Department of Energy, Office of Electricity (OE), Energy Storage Division.

On April 15-17, 2025, Sandia technical systems analyst Will McNamara moderated a panel session on the last day of the first IEEE PES Energy & Policy Forum held in Washington, D.C. The Forum was a week-long event filled with engaging and informative sessions, aimed at exploring the challenges and opportunities facing the energy sector.The panel session that McNamara moderated was entitled “Market Dynamics: Policy and Technology Landscape for LDES” and included panelists Huiyi Zhang Jackson, Senior Director of Clean Energy Technologies and Policy at the Edison Electric Institute; Todd Olinsky-Paul, Senior Project Director at Clean Energy States Alliance and Clean Energy Group; and Farnaz Farzan, Principal Advisor/Team Lead at Quanta Technology LLC. This session provided an opportunity for in-depth discussion and sharing of unique perspectives on the evolving use cases and value propositions for long-duration energy storage (LDES), current technology developments, and market reforms specific to LDES that are taking place across regional transmission organizations, independent system operators, and at the state level.Earlier in the week, McNamara also conducted a two-hour tutorial entitled “Policy and Regulation Supporting Energy Storage,” alongside Jeremy Twitchell of Pacific Northwest National Laboratory.The inaugural Energy & Policy Forum was well attended, bringing together government experts, policymakers, industry leaders, researchers, and other key stakeholders to explore strategic solutions that enhance the reliability, resilience, security, and affordability of U.S. power systems.

For more information, please visit the IEEE PES Energy & Policy Forum website.

Sandia staff members Chaired and participated in the 2025 IEEE Electrical Energy Storage Applications and Technologies (EESAT) conference, held January 20-25 in Charlotte, NC. This year’s technical program centered around the theme of ‘Energy Storage Driving Grid Transformation’.  Since 2000, EESAT has been the premier technical forum for presenting advances in energy storage technologies and applications. EESAT benefits attendees through up-to-date idea exchange with top technologists from across the global energy storage industry.

Since EESAT shifted from U.S. Department of Energy to IEEE oversight in 2024, Sandia staff have facilitated the conference’s transition from an R&D focus to adoption and application of energy storage. This has been supported primarily through the leadership of Sandia senior technical staff member David Rosewater who Chaired both the 2024 and 2025 EESAT conferences. Additional Sandia staff moderated or presented in several panels this year on topics including Long Duration Energy Storage, Energy Storage Economics and Energy Storage Applications.

The EESAT conference’s shift in focus from R&D to application has resonated with industry, with over 50% of this year’s participants coming from broader industry (non-battery companies), including 10% of the attendees coming from electric utilities.  Another indicator of broader industry relevance and interest is the 25% increase in attendance from last year. 

Learn more about EESAT and review the 2025 technical agenda at 2025 EESAT Agenda – IEEE EESAT 2025

Information on next year’s 2026 EESAT conference will be available soon at https://cmte.ieee.org/pes-eesat/