XL Batteries, a long-duration grid-scale energy storage solution provider, raised $7.5 million from Merrin Investors, the family office of entrepreneur and philanthropist Seth Merrin. With this funding, the company plans to scale its operations, enhance grid resilience, and support energy independence by reducing reliance on foreign supply chains.
The company is developing an Organic Flow Battery, which is stated to be more cost-effective, safe, and efficient, utilizing proprietary, organic, low-cost electrolytes instead of vanadium, which is mentioned to be scarce, corrosive, and more expensive.
“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.”
Earlier this year, the company partnered with Prometheus Hyperscale, a developer of sustainable hyperscale data centers, on a multi-year agreement to deploy on-site long-duration energy storage systems at data centers. In the first phase of the partnership, XL Batteries will deliver and commission a 333 kW demonstration-scale standalone Organic Flow Battery at Prometheus’ facility in 2027. After that, Prometheus intends to purchase one 12.5 MW/125 MWh commercial-scale system in 2028 and an additional 12.5 MW/125 MWh system in 2029.
In 2023, the company raised $10 million in a Seed-2 round, which was led by Catalus Capital, with additional investments from SIP Global, Xerox Ventures, and existing investors Jeffrey Schwarz, Joel Greenblatt, and Robert Goldstein.
According to Mercom’s 1H and Q2 2025 Funding and M&A for Energy Storage report, VC funding in the sector totaled $1.7 billion across 36 deals, down 29% compared to the previous year. Energy Storage Downstream companies received the most VC funding in 1H 2025. Other top-funded categories included Materials and Components, Energy Storage Systems, Sodium-based batteries, and Thermal Energy Storage companies.
In May, VFlowTech, a manufacturer of vanadium-based redox flow batteries, raised $20.5 million in a funding round led by Granite Asia, a venture capital firm. The funding raised will help the company scale up the manufacturing and deployment of its VRFBs.
