Prismatic Sodium-ion Battery development is moving quickly at Remplir. The South Korean battery startup has expanded beyond prismatic lithium iron phosphate batteries and introduced the country’s first prismatic sodium-ion battery. As a result, Remplir now stands out as the only domestic company producing both prismatic LFP batteries and prismatic sodium-ion batteries.
Remplir developed a 170Ah prismatic sodium-ion battery in June 2026. The company has already started product qualification with customers. In addition, it is conducting performance evaluations with overseas buyers for energy storage system and uninterruptible power supply applications.
Prismatic Sodium-Ion Battery Marks a First for South Korea
Remplir built prototype cells at its production facility in Hwaseong, Gyeonggi Province. Notably, the new battery uses sodium instead of lithium. Because sodium is widely available, the chemistry supports stronger cost competitiveness. Moreover, the battery targets sectors that value long cycle life, safety, and stable performance in demanding conditions.
The company said the 170Ah format focuses first on ESS and UPS markets. These segments need reliable battery performance over many cycles. Therefore, prismatic sodium-ion battery technology could gain traction quickly in stationary storage applications.
Earlier in 2026, Remplir also received an Innovation Award at InterBattery 2026 in March. That recognition added credibility to the company’s technology as it moved from development to customer qualification.
How Remplir Designed Its Prismatic Sodium-Ion Battery
Remplir uses a sodium iron phosphate, or NFPP, cathode material in its prismatic sodium-ion battery. This chemistry relies on iron, phosphorus, and sodium. These raw materials are relatively abundant. Consequently, the battery can offer a favorable cost structure.
The chemistry also avoids nickel and cobalt. That design helps lower material costs. At the same time, it supports long cycle life and strong safety performance. Remplir said the battery sees minimal structural change during charging and discharging. As a result, the cell can maintain stable operation over repeated use.
Furthermore, the company improved battery performance through its own materials formulation. Remplir designed the battery to operate from minus 40 degrees Celsius to 60 degrees Celsius. This wide temperature range makes it especially relevant for stationary storage and backup power systems that must perform in varied environments.
Prismatic Sodium-Ion Battery Production Uses Existing LFP Lines
One of Remplir’s biggest advantages is manufacturing flexibility. The company can produce prismatic sodium-ion battery cells without building a completely separate production line. Instead, it uses its existing prismatic LFP battery facilities for most of the process.
Sodium-ion and Lithium-ion batteries share many manufacturing steps. According to Remplir, only the mixing stage needs adjustment because that process blends electrode materials. Therefore, the company can move faster toward commercialization while controlling capital spending.
This production approach also reflects Remplir’s strength in material composition and formulation. By combining battery design and process expertise, the company aims to scale efficiently as demand grows.
Remplir Expands Capacity for Prismatic Sodium-Ion Battery Growth
Remplir currently operates a 100MWh production line at its Hwaseong plant. The site can produce about 150,000 battery cells per year. Now, the company is seeking to raise 100 billion won in a Series B funding round. It plans to use the proceeds to expand production capacity to the gigawatt-hour level.
The new lines will mainly produce prismatic LFP batteries. However, part of the added capacity will also support drone batteries. Meanwhile, Remplir can continue advancing its prismatic sodium-ion battery program through customer qualification and future ESS commercialization.
Chief Executive Kim Su-jin said sodium-ion batteries remain at an early stage of commercialization. However, that timing also creates room to establish a new supply chain. After customer qualification with North American customers, the company plans to commercialize ESS products and broaden its portfolio.
Remplir’s Broader Battery Strategy in 2026
Alongside its sodium-ion work, Remplir continues to build its prismatic LFP battery business. The company supplies 340Ah cells for ESS applications and 230Ah cells for heavy equipment and agricultural machinery. It also develops customized battery cells based on customer needs, starting from electrode design.
That strategy fits broader electrification trends. Construction equipment, agricultural machinery, forklifts, and golf carts are shifting from diesel engines and lead-acid batteries to lithium battery systems. Accordingly, demand for prismatic battery cells is rising in industrial markets.
Kim said the domestic market for prismatic LFP batteries is growing rapidly as industrial equipment electrifies. He also said demand is increasing for locally produced alternatives. Remplir expects revenue to exceed 12 billion won in 2026. That figure would be more than ten times last year’s level.
Overall, Remplir’s new prismatic sodium-ion battery gives the company a notable first in South Korea. More importantly, it strengthens its position in energy storage and backup power markets. With a 170Ah cell, existing manufacturing infrastructure, and ongoing customer qualification, Remplir is building a clear path toward sodium-ion commercialization in 2026.
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