SOLID-STATE SODIUM BATTERY

The invention refers to a solid-state sodium battery comprising a positive electrode compartment comprising a positive electrode, said positive electrode comprising a compound of formula NaFexMnyNizO2, wherein x is more than 0 and equal or less than 1, y is more than 0 and equal or less than 1, and z is more than 0 and less or equal than 1, and wherein said compound is a neutral oxide; and a catholyte, said catholyte comprising a salt of formula NaX, wherein Na is a sodium cation and X is an anion selected from the group consisting of trifluoromethanesulfonyl imide; fluorosulfonyl trifluoromethanesulfonyl imide; and a polymer; a negative electrode compartment comprising a negative electrode, said negative electrode comprising solid metallic sodium or an alloy comprising solid metallic sodium; and an electrolyte composition; wherein the mass loading of the compound of formula NaFexMnyNizO2 is equal or higher than 1.0 mAh·cm-2. Moreover, the invention refers a module system which comprises at least two stacked batteries as defined above and to the use of said solid-state sodium battery as an energy storage device.