Sodium-ion BESS: CATL in 2GWh Eastern Europe collaboration, ESS Inc signs LOI for 500MWh of US deployments

In April, ESS signed an LOI for a strategic partnership with US Na-ion battery startup Alsym Energy, seeing ESS add 8.5GWh of Alsym’s cells and modules to its portfolio.

Alsym uses a proprietary version of sodium iron phosphate pyrophosphate (NFPP) cathode material that it has dubbed NFPP+, with an added “best-in-class energy density and no possibility of entering thermal runaway.”

Contingent on successful execution and future development, Juniper Energy intends to procure at least 500MWh of ESS BESS by 2032.

ESS Inc was founded in 2011 and has been primarily known as the technology developer and holder of IP for a proprietary flow battery based on an iron and saltwater electrolyte, designed for long-duration energy storage (LDES) applications. The company got its listing on the New York Stock Exchange (NYSE) in 2021 and has struggled to reach profitability. This has led to recent strategic changes, such as pivoting first toward a larger form factor iron flow battery solution.

Although it appears to remain active in that space, ESS Inc has added sodium-ion BESS integration to its offerings. The company is due to release its Q2 2026 financial results on 13 August.

Last month, ESS joined several Na-ion and alternative battery companies to launch the American Battery Leadership Coalition (ABLC). Members include Na-ion startups Peak, Alsym, Batri, and Mana Battery; separator manufacturer Microporous; chemical company Ingevity; domestic manufacturer Re:Build Manufacturing; and NAION, which is building North America’s first Na-ion gigafactory.

At the time of announcement, Graeme Grant, COO of Alsym Energy said, “Importantly, Na-ion is built on abundant global resources, for some of which the US has a structural competitive advantage, and none of which are rare earth minerals. This means we can create a competitive and sustainable domestic, non-Foreign Entity of Concern (FEOC) supply chain. As raw material and manufacturing costs continue to decline, sodium-ion batteries are positioned to become the low-cost leader for stationary storage applications.”

ABLC said it will need favourable policy support to advance Na-ion at pace and compete with China, which has made significant progress in the scaling of Na-ion cells.

In May, Juniper announced a 500MWh strategic partnership with Alsym. Alsym will deploy 500MWh of its Na-ion BESS solution across California, although it is not clear if the latest announcement refers to the same deal framework given ESS Inc’s relationship with Alsym.

As was the case in May, Juniper Energy’s website remains a single page with limited company information, built on Wix. Founder and managing partner Keith McDaniels is the only employee listed on LinkedIn, with a background as an attorney at bankruptcy and restructuring firm Keller Benevenutti LLP.

When dialing the number on Juniper’s website, a message plays informing callers that it is out of service. Energy-Storage.news asked Juniper for further information on the company via email but did not receive a response prior to publication.

CATL and Solarpro deploying Na-ion BESS in Eastern Europe

In related news from Europe, battery manufacturer CATL and EPC firm Solarpro Technology AD have signed a strategic cooperation agreement for 2GWh Na-ion systems.

Announced 21 July, CATL and Solarpro will explore Na-ion solutions “tailored to diverse application scenarios across Central and Eastern Europe.”

CATL stated that the collaboration will allow it to gain insight into the local market, address real-world operational challenges, and identify new applications for Na-ion technology in the region.

The new agreement also builds on the long-standing partnership between CATL and Solarpro. In May 2026, through joint efforts, the companies successfully connected a 602MWh large-scale BESS project to the national power grid in Bulgaria, increasing the country’s total energy storage capacity by 10%.

CATL has not specified which material is being used for its latest Na-ion roll-outs, but the company has previously used a Prussian blue analogue (PBA) for its cathode material, specifically Prussian white (PW). Vickrant V. Gharat and Manishkumar D. Yadav wrote in The Journal of Alloys and Compounds in 2025 that PW has “strong ionic conductivity, quick Na⁺ diffusion, and advantageous redox potential.”

The authors further stated, “Prussian white is commonly synthesised through the co-precipitation method, which might introduce defects and vacancies into the crystal lattice or [Fe(CN)6]4- vacancies. These vacancies can enhance ionic conductivity to some extent, but they lead to structural collapse and hinder ion migration during cycling due to occupation by water molecules.”

Columbia University’s Consilience: The Journal of Sustainable Development wrote in a 2022-2023 issue, that CATL “have achieved up to 160 Wh/kg, nearing the energy density of lithium-ion batteries, and the ability to charge to 80% within 15 minutes,” with PW.

Clean technology news site CleanTechnica reported earlier this year on a CATL patent describing antimony’s role in reducing moisture effects. The patent characterises antimony as “reinforcing” the cathode matrix, facilitating cheaper water-based production methods..

CATL launched its Na-ion BESS for the European market at the Smarter E Europe trade show in Germany in June.

Earlier this month, system integrator Alfen and CATL agreed to deploy 5GWh of CATL’s Na-ion BESS across Europe.

Solarpro is a subsidiary of Austrian clean energy investor Renalfa Solarpro Group and previously made an agreement with Chinese vertically integrated lithium-ion battery manufacturer Hithium to use its 6.25MWh DC block solution in Eastern European projects.

Battery Asset Management Summit USA 2026 will be held 15-16 September in Garden Grove, California, hosted by Energy-Storage.news publisher Solar Media (part of the Informa Group). The agenda emphasises addressing the roles of AI, cybersecurity, and second-life applications, broken down into two tracks: Technical Asset Management and Commercial Asset Management. This year, the conference is also co-located with Solar & Storage Finance Summit USA. Visit the official site for more details.