Sodium probably won't replace lithium in mobile batteries: phones, laptops, ebikes, cars. Sodium is bulkier and less energy dense.

But, a world powered by environmentally friendly forms of energy will have peaks and troughs. Batteries could store grid power and work at night or when the wind isn't blowing. There are already times in Australia where electricity is absolutely free because the sun is shining and solar cells are generating more energy than the grid needs. With enough batteries, Australia could presumably go 100% renewable.