Prometheus Hypescale-backed long-duration battery developer XL Batteries has secured a $7.5 million investment from Merrin Investors.

The organic flow battery developer said that the new funding will help it accelerate the scaling of its operations, enhance grid resilience, and support energy independence by reducing reliance on foreign 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.”

Earlier this year, XL became one of the first long-duration energy storage (LDES) companies to partner with a data center company. In May, it signed an agreement with Prometheus to deploy on-site LDES across the company’s data center portfolio.

The deployment will occur over several phases. In the initial phase, XL will supply and install a 333kW demonstration-scale, standalone Organic Flow Battery at an undisclosed Prometheus site in 2027. Following this, Prometheus plans to acquire a 12.5MW/125MWh commercial-scale system in 2028, with another identical system to follow in 2029.

XL’s battery technology utilizes organic molecules designed to remain stable in both charged and discharged states. Unlike metal or element-based chemistries, the organic compounds can be engineered at the molecular level. XL sources the materials from widely available feedstocks rather than rare minerals, reducing exposure to supply chain disruptions and geopolitical risks.

According to the company, this approach yields batteries with lifespans exceeding 20 years, eliminating the need for rare earth materials and making the system significantly more sustainable.

Since then, several other data centers have partnered with LDES firms to explore the technology. Most notably, in July, Google signed its first partnership with an LDES firm, inking a long-term agreement with Energy Dome, an Italian company specializing in CO2 battery development.

Following this, earlier this month, Google signed a partnership with Arizona-based public power utility, Salt River Project, to improve the understanding of non-lithium-ion LDES performance at a grid level.

DCD took a closer look at the potential of flow batteries within the data center sector in our latest Critical Power Supplement. Available here.