ESS Tech, Inc (NYSE: GWH), a manufacturer of long-duration energy storage systems, has signed a letter of intent with Alsym Energy to form a strategic partnership aimed at deploying 8.5 GWh of sodium-ion battery capacity. The agreement will see Alsym supply advanced sodium-ion cells and modules to expand ESS’ portfolio with non-lithium energy storage solutions.
The collaboration marks ESS’ entry into the short- and medium-duration battery energy storage system (BESS) segment, which has largely been dominated by lithium-ion technologies. By adding sodium-ion batteries to its offerings, the company is widening its market reach beyond long-duration storage and addressing a broader range of customer requirements.
Alsym’s sodium-ion technology is designed to offer a safer alternative to conventional lithium-based systems by eliminating risks linked to thermal runaway. The batteries are non-flammable and operate without the need for complex cooling infrastructure, helping reduce system costs and simplify deployment. The technology also delivers high efficiency along with rapid charge and discharge capabilities, making it suitable for a wide range of stationary storage applications.
Drew Buckley, Chief Executive Officer of ESS, said the partnership brings together complementary technologies. He noted that sodium-ion solutions are well suited for applications requiring high power and fast cycling, while ESS’ iron flow systems cater to long-duration needs with extended asset life and consistent performance. Together, the combined platform enables customers to address varying storage requirements through a single provider.
Randall Selesky, Chief Commercial Officer at ESS, said the agreement represents a key step in the company’s strategy to offer a full spectrum of non-lithium storage solutions. He added that integrating Alsym’s sodium-ion technology with ESS’ expertise in system design and deployment creates a pathway for customers seeking alternatives to lithium-ion batteries without compromising on performance or cost.
Alsym’s Na-Series batteries are built using abundant raw materials and a proprietary platform that accelerates battery development. The technology supports safe operations across a wide temperature range and reduces reliance on extensive safety systems, contributing to lower overall ownership costs.
Mukesh Chatter, Chief Executive Officer of Alsym Energy, said the partnership combines ESS’ experience in grid-scale storage with Alsym’s focus on advanced battery chemistry. He highlighted the growing need for scalable and secure energy storage solutions as demand continues to rise.
ESS Inc (NYSE: GWH) is a leading manufacturer of long-duration energy storage systems based on iron flow technology. Founded in 2011, the company is focused on advancing decarbonisation through safe, sustainable, and durable storage solutions. Its technology uses widely available materials such as iron, salt, and water to deliver reliable and resilient energy storage. Designed for flexibility, ESS systems help utilities and businesses manage rising power demand, improve grid stability, and optimise the use of surplus renewable energy without disruption.
Alsym Energy is driving the next generation of battery innovation by reimagining chemistry for safer and more scalable energy storage. Its flagship Na-Series batteries are sodium-ion based, non-flammable, and built using abundant raw materials, making them a cost-effective alternative for a wide range of applications. The company leverages a proprietary, physics-informed artificial intelligence platform to accelerate material discovery and battery development, significantly reducing the time required to move from concept to commercial deployment.
By integrating advanced battery science with AI-led design, Alsym Energy has developed a closed-loop system that streamlines the entire development cycle—from research and prototyping to manufacturing. The Na-Series technology eliminates the risk of thermal runaway, enabling safe deployment across diverse environments, including data centres, industrial operations, residential and commercial buildings, mining sites, defence installations, and utility-scale grids.
Engineered for performance, these batteries operate efficiently across a broad temperature range, removing the need for complex cooling or heating systems. Their capability for rapid charging and discharging supports multiple cycles per day, enhancing operational efficiency and economic returns.
