In 2022, the energy density of sodium-ion batteries was right around where some lower-end lithium-ion batteries were a decade ago—when early commercial EVs like the Tesla Roadster had already hit the road. Projections from BNEF suggest that sodium-ion batteries could reach pack densities of nearly 150 watt-hours per kilogram by 2025.
A typical sodium-ion battery has an energy density of about 150 watt-hours per kilogram at the cell level, he said. Lithium-ion batteries can range from about 180 to nearly 300 watt-hours per kilogram. I asked Srinivasan what he makes of CATL’s claim of a sodium-ion battery with 200 watt-hours per kilogram.
Sodium-metal batteries (SMBs) are emerging as a high-energy-density system toward stationary energy storage and even electric vehicles.
Sodium-ion batteries have several advantages over competing battery technologies. Compared to lithium-ion batteries, sodium-ion batteries have somewhat lower cost, better safety characteristics (for the aqueous versions), and similar power delivery characteristics, but also a lower energy density (especially the aqueous versions).
“From a physics perspective, sodium batteries inherently have lower energy density than lithium batteries.” A typical sodium-ion battery has an energy density of about 150 watt-hours per kilogram at the cell level, he said. Lithium-ion batteries can range from about 180 to nearly 300 watt-hours per kilogram.
The process of manufacturing sodium-ion batteries is similar to that of lithium-ion batteries, or at least similar enough that companies can shift existing assembly lines without having to spend heavily on retooling. But sodium-ion batteries have some disadvantages. The big one is low energy density compared to lithium-ion.