Many MindedSodium-ion cells edge toward lithium iron phosphate for grid storage
Commercial sodium-ion cells now reach an energy density of about 175 Wh/kg, according to Silvia Bodoardo, a professor at the Polytechnic University of Turin and scientific representative of the Batteries European Partnership Association. Advanced lithium iron phosphate cells reach roughly 205 Wh/kg. She told pv magazine the difference matters little for stationary storage, where weight is far less critical than in electric vehicles.
She also says commercial-grade sodium-ion cells keep over 95% of their capacity after 5,000 full-depth cycles. CATL's second-generation sodium-ion technology reportedly works from -40 C to 70 C and holds about 90% of capacity at -40 C. CATL launched its sodium-ion energy storage system in June 2026 and expects cumulative shipments of about 1 GWh by year-end, with international deliveries beginning in 2027. In September 2026, Altris, Clarios and InoBat reported that their European sodium-ion platform had completed customer validation.
The significance is supply. Grid batteries compete with vehicles for lithium, and a chemistry that needs none removes one constraint on building storage at scale. If sodium-ion matches lithium on cycle life and cost where weight is irrelevant, clean power becomes easier to store and cheaper to firm up. Bodoardo sees the market splitting between batteries of roughly two to six hours and true long-duration storage. Vanadium flow, zinc-based and iron-air technologies are aiming at the latter, and gigawatt-hour-scale flow projects have been proposed.
Keep the scale in view. Sodium-ion was under 1% of global lithium-ion production in 2025. The cycle-life and density figures rest largely on one expert's statements rather than independent testing, the CATL low-temperature numbers are reported rather than verified, and the 1 GWh shipment figure is an expectation. Watch for real deliveries and independent test data.
Source: pv magazine