ESS Tech, Inc. has acquired the intellectual property and assets of VoltStorage to expand its long-duration energy storage portfolio. The transaction integrates iron flow and iron-salt battery technologies, adding patents, technical development assets and engineering personnel. ESS stated the combined platform is intended to support scalable manufacturing in the US and deliver extended-duration energy storage solutions for utilities, renewable energy projects and industrial applications.
PROJECT SNAPSHOT
U.S.-based long-duration energy storage solutions provider, ESS Tech, Inc. has acquired the intellectual property and selected assets of VoltStorage GmbH, a Germany-based developer of iron-salt battery technology. The transaction adds VoltStorage’s patent portfolio, technical documentation and research and development assets to ESS’s existing iron flow battery platform.
According to ESS, the acquisition integrates complementary iron-based chemistries intended for long-duration energy storage (LDES) applications. VoltStorage’s iron-salt battery development work will be combined with ESS’s established iron flow technology, which uses iron, salt and water as core materials. The company stated that the combined technology base is designed to support flexible discharge duration and competitive Levelized Cost of Energy (LCOE) for grid-scale and distributed storage projects.
As part of the agreement, selected VoltStorage executives and engineering personnel have joined ESS. ESS indicated that this technical integration is expected to support product development, testing and potential commercialization pathways across multiple market segments.
The expanded technology portfolio is intended to address utility-scale storage, renewable energy integration and industrial microgrid applications. Long-duration storage systems are typically deployed to store excess generation from intermittent renewable sources and discharge electricity over extended periods, supporting grid reliability and energy shifting requirements. ESS stated that combining its iron flow platform with VoltStorage’s iron-salt advancements may broaden the operational range and design flexibility of future product offerings.
The company also noted that international development expertise will be integrated into its U.S.-based manufacturing operations. ESS operates manufacturing facilities in the United States and focuses on scaling production of iron-based battery systems. The addition of VoltStorage’s intellectual property is expected to enhance internal research capabilities and support ongoing product optimization efforts.
Long-duration storage technologies are increasingly being evaluated for their ability to provide extended discharge capabilities beyond typical four-hour systems. ESS indicated that the combined platform will focus on delivering scalable systems designed to support grid reliability, renewable integration and cost performance over extended operational lifecycles.
Drew Buckley, CEO of ESS, said that the acquisition is intended to expand the company’s long-duration energy storage portfolio. He added that integrating iron flow and iron-salt battery expertise is aimed at advancing the development of an enhanced iron-based platform for multi-hour storage applications.