Products
NAS Batteries (Sales Discontinued)
Notice Regarding Discontinuation of Manufacturing and Sales Activities of NAS Batteries
NGK INSULATORS, LTD. hereby announces that, at the Board of Directors meeting held on October 31, 2025, it has resolved to discontinue the manufacturing and sales activities of NAS batteries under its Energy Storage Business.
NAS batteries are manufactured by NGK. The batteries feature high capacity, high energy density, long life, and compact dimensions one-third those of lead batteries, enabling stable power supply for extended periods. NAS batteries make it possible to implement peak load shaving and load balancing and help stabilize renewable energy output , thereby contributing to power-saving measures, cutting energy costs, and reducing environmental impact.
NAS batteries have obtained the certification based on UL 1973 standard* (cell and module level) and a test report based on UL 9540A standard* (container type including cells and modules on mounted) .
NAS batteries are rechargeable storage batteries that incorporate anodes (negative electrode) comprised of sodium (Na) and cathodes (positive electrode) comprised of sulfur (S), separated by a fine ceramic solid electrolyte. They can be repeatedly charged and discharged through sulfur-sodium chemical reactions.
NGK has pursued joint research and development with Tokyo Electric Power Company Holdings, Inc., based on the idea of using sodium sulfur batteries to address fluctuating demand for electricity—for example, between the day and night.
* UL 1973 and UL 9540A standard is safety standard for stationary storage batteries issued by UL Solutions, a global independent safety science company.
Operation principle
During discharge
- Molten sodium donates electrons to the external circuit at the anode
- The resulting ions Na+ migrate to the cathode through the beta-alumina solid electrolyte that
separates the two liquid electrodes and that acts as a superionic conductors - The volume of liquid at the anode therefore decreases
- Arriving at the cathode, Na+ ions combines with molten sulfur which reacts with the electrons
coming from the external circuit, forming sodium polysulfide Na2Sx - The volume of liquid at the cathode therefore increases
2 Na + x S → Na2Sx with 3.3 ≤ x ≤ 5
During charge
- The reverse process takes place
System
Container type unit
The battery unit and control equipment are housed in a 20-foot (approximately 6-meter) container.
| Rated Output | 800kW |
|---|---|
| Rated Capacity | 4,800kWh |
| Configuration | Container (33 kW module × 6 units) × 4 sets |
| Dimension | 6.5W × 5.6D × 5.5H（m） |
Package type unit
The package is assembled on site and the battery modules are housed inside.
| Rated Output | 1,200kW |
|---|---|
| Rated Capacity | 8,640kWh |
| Configuration | 30 kW module × 40 units |
| Dimension | 10.2W × 4.6D × 4.8H（m） |
* NAS and the NAS logo are trademarks of NGK INSULATORS, LTD., registered in the U.S. and other countries.
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