Unfortunately, sodium ions are three times heavier and a third larger than lithium ions seen in other battery chemistries. Because electrodes in sodium-ion batteries must be thicker and heavier to hold the same amount of energy, isn’t practical solution and are most useful in low-cost small city cars, like the BYD Seagul or two-wheelers that don’t need the higher energy density. Sodium ion bateries would be useful where cheap large storage facilities are required and the size of the battery pack wouldn’t matter, such as Wind Farms for example.