ESS Tech Claims the Crown in Iron-Salt Chemistry

ESS Tech acquires VoltStorage assets to dominate the long-duration battery market and solidify its iron-flow patent portfolio

24 Feb 2026

The transition to renewable energy has a timing problem, and ESS Tech thinks it has the solution. By acquiring the intellectual property of VoltStorage, a German firm that shuttered last year, the Oregon-based manufacturer is doubling down on iron-salt chemistry. This deal brings a deep library of patents and a seasoned team under one roof to tackle the grid's biggest headache: keeping the lights on when the sun goes down.

Most batteries today rely on lithium-ion, which works well for smartphones but struggles to power a city for an entire day. ESS Tech specializes in iron flow technology, using simple ingredients like iron, salt, and water to store power for up to 22 hours. VoltStorage’s technology offers a similar endurance, boasting a lifespan of 10,000 cycles without the typical degradation that plagues modern electronics. This merger creates a powerhouse of endurance-focused engineering.

The move is as much about people as it is about chemistry. Randall Selesky, the former commercial lead at VoltStorage, has joined ESS Tech to sharpen the company's market strategy. CEO Drew Buckley views this as an acceleration of their mission to provide affordable, long-duration storage. The company is preparing for major deployment milestones throughout the next two years, aiming to satisfy a growing appetite among utility providers.

Consolidation is becoming the norm as the energy sector matures. While ESS Tech reported a significant net loss in 2025, it remains focused on a domestic manufacturing strategy that integrates international expertise. The grid needs more than a four-hour buffer to remain stable. By absorbing its rivals, ESS Tech is positioning itself as the primary alternative to lithium-heavy systems for the long haul.