While the sodium-ion battery technology is very versatile and can essentially be tailored to suit any application, it is widely believed that the first usage of sodium-ion batteries would be for all applications which are currently being served by lead-acid batteries. For such lower energy density applications, sodium-ion batteries would essentially be delivering much higher energy densities than current lead-acid batteries (1 – 5 times higher) at similar costs with enhanced performance (efficiency, safety, faster charging/discharging capabilities and cycling stabilities). These applications could be for smart grids, grid-storage for renewable power plants, the car SLI battery, UPS, telecoms, home storage and for any other stationary energy storage applications. The higher energy density sodium-ion batteries (typically those using non-aqueous electrolytes) would be well suited for those applications currently dominated by lithium-ion batteries. Among the lower energy density spectrum of such high energy density batteries, applications such as power tools, drones, low speed electric vehicles, e-bikes, e-scooters and e-buses would benefit from the lower costs of sodium-ion batteries with respect to those of lithium-ion batteries at similar performance levels (safety being in favour of sodium-ion batteries). It is expected that with the current rate of rapid progress in the field of sodium-ion batteries, such batteries would be eventually used in applications requiring very high energy density batteries (such as long-range electric vehicles and consumer electronics such as mobile phones and laptops) which are currently served by high cost and high energy density lithium-ion batteries.