US energy storage companies Syntropic Power and Unigrid have formed a partnership to commercialise sodium chromium oxide battery technology in North America, with plans to deploy 1 GWh of systems in 2027.
The companies will use Unigrid’s sodium chromium oxide, or NaCrO₂ (NCO), chemistry in Syntropic’s residential and grid-scale energy storage products. They will also investigate manufacturing NCO cells in the US.
Syntropic will design, manufacture and deploy the battery energy storage systems. The initial programme will include its wall-mounted Tenet system for residential, light-commercial and virtual power plant applications, and its modular GridSpan DC platform for larger stationary installations.
GridSpan is being developed in separate power and energy configurations for applications ranging from fast-response power and ride-through services to storage durations of approximately 20 minutes to 20 hours.
NCO is one of several cathode chemistries being developed for sodium-ion batteries. It differs from sodium nickel iron manganese oxide and sodium iron pyrophosphate chemistries being commercialised by a number of Chinese manufacturers.
Syntropic commissioned testing at Rochester Institute of Technology
Syntropic commissioned the Rochester Institute of Technology Battery Development Center, an ISO 17025-accredited laboratory, to test Unigrid’s 70 Ah and 210 Ah prismatic cells.
Initial testing of the larger cells measured discharge capacities of 216–218 Ah, compared with the nameplate rating of 210 Ah. Cell-level round-trip energy efficiency was reported to be at least 97.9%, while capacity declined by 2.3% when the discharge rate was increased from C/10 to 1C.
The cells also displayed endothermic behaviour while charging. Syntropic said the test results were being used to inform GridSpan’s electrical architecture, operating controls and passive thermal-management design, with the aim of operating the system without mechanical cooling.
Cycle-life testing conducted by Unigrid, rather than RIT, has recorded more than 1,000 full-depth-of-discharge cycles with more than 99% of capacity retained, according to the companies.
Matt Huber, chief technology officer of Syntropic Power, said: “The RIT program gives us independent data on the performance characteristics that matter for stationary energy storage. Unigrid’s NCO chemistry combines high round trip efficiency, high power capability, strong cycle life performance and distinctive thermal safety behavior, providing the foundation for a GridSpan platform designed to operate without active cooling.”
RIT also conducted abuse testing, during which the companies said the cells remained thermally stable under extreme test conditions. Unigrid’s cells have passed UN 38.3 transport testing, completed cell-level UL 9540A testing and received IEC 62619 certification.
The first shipment of NCO cells has been delivered to Syntropic for product development, testing and integration.
Darren HS Tan, chief executive officer of Unigrid, said: “As surging power demand from AI and electrification collides with extreme weather and rising energy costs, the modern grid requires unmatched reliability and thermal resilience. The inherent stability and high power capability of the NCO chemistry make it exceptionally well-suited for these demanding conditions. Partnering with Syntropic allows us to scale this robust technology to deliver the dependable power infrastructure North America urgently needs.”
Unigrid was spun out of the University of California, San Diego. The company has developed its sodium-ion cells with the intention of using existing lithium-ion battery manufacturing infrastructure.
Under the partnership, Syntropic will lead system development and certification, as well as US module assembly and system integration. The companies aim to establish a supply chain that does not involve organisations classified under US rules as Foreign Entities of Concern by the end of 2027.
Phillip Martin, chief executive officer of Syntropic Power, said: “Syntropic makes safe, accessible and sustainable energy practical at scale. By pairing independently validated chemistry with U.S. manufacturing and purpose-built system design, this partnership creates a credible path to produce and deploy sodium-ion storage in North America.”
Photo: Syntropic commissioned the Rochester Institute of Technology Battery Development Center to independently test sodium-chromium-oxide (NaCrO₂) cells supplied by Unigrid © Syntropic
