ESS Tech, a manufacturer of iron flow long-duration energy storage solutions (LDES), has announced the acquisition of the intellectual property and assets of iron-salt battery company VoltStorage.
VoltStorage filed for bankruptcy last year amid challenging market conditions, shifting investment cycles, and strategic headwinds.
As part of the transaction, VoltStorage’s key executive and engineering teams will join ESS, strengthening the company’s commercial and technical capabilities.
This acquisition is said to combine two complementary technologies to deliver the flexible, cost-effective LDES solution available on the market. The combined technology is expected to offer a wider range of applications, from grid-scale storage to industrial microgrids, and to deploy international development expertise at ESS’s American manufacturing facility.
“This acquisition accelerates our mission to provide clean, reliable, and affordable energy storage solutions worldwide,” said Drew Buckley, CEO of ESS. “By combining decades of iron flow battery expertise across two companies at ESS, we are accelerating innovation to create the most advanced iron-salt battery platform for long-duration storage.”
In mid-2025, ESS Tech closed $31 million in insider-led funding measures. The funding package primarily involves the execution of a standby equity purchase agreement with YA II PN, granting ESS the right, but not the obligation, to sell up to $25 million of common equity to YA II PN over a 3-year period.
According to Mercom’s Annual and Q4 2025 Funding and M&A for Energy Storage report, the corporate M&A activity decreased, with 22 companies acquired in 2025 compared to 25 in 2024.
In August 2025, FlexGen Power System, a provider of battery energy storage solutions and energy management software, announced the acquisition of a significant portion of Powin’s business. Through the acquisition, FlexGen owns all of Powin’s IP, including hardware and software IP, as well as information technology systems, along with a significant spare parts inventory.
