The necessary energy shift towards the use of renewable energy resources in our society today requires the simultaneous and fast development of large scale and cost effective energy storage systems. This has become expedient due to the steadily growing need for mobile energy storage systems for information technology and electromobility, as well as the need for the discontinuation of power plants based on fossil fuels. A sodium-ion-based energy storage battery is one of the alternative energy storage systems that can be deployed to meet some of these targets. This is because sodium is naturally abundant and is less expensive in comparison to lithium, in addition to the similarity of the electrochemical properties of sodium-ion-based batteries to that of lithium-ion-based batteries. This chapter reviews the working principle of a sodium ion battery (SIB), the stability windows, and capacities of some of the cathode materials used in sodium-ion-based batteries.