Marlborough, Massachusetts - Sep 17, 2025 (UTC) - XL Batteries, an energy storage company that is building the lowest-cost, safest and most efficient form of long-duration energy storage (LDES), today announced a $7.5 million investment from Merrin Investors, the mission-driven family office of entrepreneur and philanthropist Seth Merrin. This new funding accelerates XL Batteries’ ability to scale its operations, enhance grid resilience, and support energy independence by reducing reliance on foreign supply chains.
As grids face rapidly rising stress from data centers, mass electrification and manufacturing, scalable, safe, and flexible LDES solutions are critical to maintaining resilience. Flow batteries offer a proven solution, but reliance on scarce, expensive materials has historically made them prohibitively costly and risky for mass deployment. XL Batteries is addressing this challenge with its low-cost, safe, and efficient Organic Flow Battery. By utilizing proprietary, organic, low-cost electrolytes instead of scarce, corrosive and expensive vanadium, its technology reduces risk and costs and eliminates the need for specialized infrastructure or supply chains.
“This investment from Merrin Investors underscores that XL Batteries is built to thrive in today’s environment,” said Tom Sisto, Co-Founder and CEO of XL Batteries. “Over the past several months, XL has hit several key milestones that prove our technology is effective. Now, with Merrin’s support, we are bringing the next generation of safe, cost-effective, long-duration batteries to market at a pace to meet growing demand.”
XL’s capital-light approach and commercial readiness position the company for success in the LDES technology race. The company’s technology can meet virtually any power need, enabling utilities, data centers, and industrial users to maintain reliable access to power. XL Batteries recently announced several key deployment milestones, including a strategic partnership with Prometheus Hyperscale for large-scale deployments at data center campuses – a first for flow batteries in the United States – and a commercial-scale pilot project with Stolthaven Terminals in Houston, Texas.
“I’m thrilled to back XL Batteries because they are rewriting the rules of industrial-scale storage,” said Seth Merrin, Founder of Merrin Investors. “Its breakthrough, non-flammable technology delivers lower cost, longer life, and greater safety than anything else on the market. This investment will help accelerate the company’s ability to lead a trillion-dollar market while supporting the clean-energy transition — a perfect example of doing well by doing good.”
The funding comes at a time when XL Batteries is demonstrating strong momentum in the energy storage sector, with new capital fueling the company’s growth while other storage players face headwinds. This latest round brings the startup’s total funding to date to $28 million, according to industry reports.
About XL Batteries
Founded by Columbia University scientists, XL Batteries is pioneering the world’s lowest-cost, safest, and most efficient long-duration energy storage solution. By combining proven flow battery architecture with a patented organic chemistry, its revolutionary technology meets the unique needs of grid operators, independent power producers, data centers and heavy industry. To learn more, please visit www.xlbatteries.com.
About Merrin Investors
Merrin Investors is the family office of Seth Merrin, founder of multiple category-defining companies in Fintech, Biotech, and Infratech. The firm is mission-driven, working alongside portfolio companies to accelerate growth and maximize impact. Merrin Investors’ philosophy is simple: do well by doing good — building enduring businesses that deliver both strong returns and positive change.
Media Contact:
Shiyun Fu
Antenna Group
xlbatteries@antennagroup.com
