Prismatic Sodium-ion Battery development is moving ahead at Remplir, a South Korean battery startup that now makes both prismatic lithium iron phosphate batteries and prismatic sodium-ion batteries. Moreover, the company says it has completed a 170Ah prismatic sodium-ion battery and started customer qualification. This step expands Remplir beyond its established prismatic LFP business and strengthens its position in energy storage and backup power applications.
Prismatic sodium-ion battery marks a first for South Korea
Remplir says it developed South Korea’s first prismatic sodium-ion battery in June 2026. The company built the product as a 170Ah cell. In addition, it began qualification work with customers soon after development. This gives Remplir an early position in a battery segment that is attracting attention for energy storage systems, or ESS, and uninterruptible power supply, or UPS, uses.
The company is currently the only South Korean manufacturer producing both prismatic LFP batteries and prismatic sodium-ion batteries. Notably, even the country’s three largest battery makers do not produce prismatic sodium-ion batteries domestically. As a result, Remplir has carved out a distinct niche in the local battery industry.
Why Remplir’s prismatic sodium-ion battery matters
Sodium-ion batteries use sodium instead of lithium. Therefore, they rely on raw materials that are more widely available. Remplir’s battery uses a sodium iron phosphate, or NFPP, cathode. This chemistry uses iron, phosphorus, and sodium. Consequently, the battery offers strong cost competitiveness while avoiding nickel and cobalt.
The company also says the chemistry supports long cycle life and strong safety. During charging and discharging, the material structure changes only minimally. As a result, the battery maintains stable performance over time. Remplir also applied its own materials formulation to improve battery performance.
In addition, the battery is designed to operate in harsh temperatures. Remplir says the operating range runs from minus 40 degrees Celsius to 60 degrees Celsius. That wide range supports use in demanding environments, especially for stationary storage and backup systems.
Prismatic sodium-ion battery targets ESS and UPS markets
Remplir manufactured prototype cells at its facility in Hwaseong, Gyeonggi Province. Then, the company started performance evaluations with overseas customers. Right now, Remplir is targeting ESS and UPS applications first. These markets value long cycle life, dependable operation, and safe battery chemistry.
ESS remains a logical first market for sodium-ion batteries. Likewise, UPS systems need reliable power during outages and grid disruptions. Because of that, Remplir’s 170Ah prismatic sodium-ion battery fits well with stationary power needs.
Remplir uses existing lines to produce its prismatic sodium-ion battery
One of Remplir’s biggest advantages is manufacturing flexibility. The company says it can produce sodium-ion batteries on its existing LFP production lines. Most manufacturing steps stay the same as Lithium-ion battery production. Only the mixing stage requires changes, because electrode materials differ.
Therefore, Remplir does not need to build a fully separate line for early sodium-ion production. This approach can reduce capital demands and speed up commercialization. At the same time, the company points to its material composition and formulation know-how as a key competitive strength.
Recognition and expansion plans for the prismatic sodium-ion battery business
Earlier in 2026, Remplir received an Innovation Award at InterBattery 2026 in March. That recognition added visibility to the company’s battery technology. Since then, Remplir has continued qualification work with overseas customers, including North American partners.
Chief Executive Kim Su-jin said the company plans to complete customer qualification and then commercialize ESS products. After that, Remplir aims to broaden its product portfolio. This roadmap shows that the company sees sodium-ion batteries as a practical addition to its battery lineup, not just a research effort.
How Remplir’s broader battery business supports growth
Remplir currently operates a 100MWh production line at its Hwaseong plant. The line has annual capacity of about 150,000 battery cells. In addition, the company is seeking to raise 100 billion won in a Series B round. It plans to use the funds to expand capacity to the gigawatt-hour level, grow manufacturing facilities, and support research and development.
The new lines will mainly produce prismatic LFP batteries. However, part of the capacity will support drone batteries. This broader manufacturing base supports Remplir’s expansion strategy and gives it room to scale products for several industrial markets.
Beyond sodium-ion, Remplir also supplies 340Ah cells for ESS applications and 230Ah cells for heavy equipment and agricultural machinery. These products serve sectors that are moving from diesel engines and lead-acid batteries to lithium batteries. As electrification spreads, demand for prismatic cells continues to rise.
Prismatic sodium-ion battery strengthens Remplir’s market position
Remplir’s new prismatic sodium-ion battery adds another layer to its battery portfolio. The company combines local production, flexible manufacturing, and application-focused design. Furthermore, it backs that approach with clear production targets and customer qualification work.
With a 170Ah cell, an operating range of minus 40 degrees Celsius to 60 degrees Celsius, and compatibility with existing production lines, Remplir is building a practical path for sodium-ion commercialization in 2026. For South Korea’s battery sector, that makes Remplir an important company to watch in ESS and UPS battery development.
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