Lithium-ion batteries dominate modern society due to their high energy density, light weight and rechargeability, powering smartphones, electric vehicles and large energy storage systems. However, they come at a high cost because of their rare earth mineral components and the environmental damages associated with mining them.

To offer a sustainable and ethical alternative, scientists are developing sodium-ion batteries, which are less expensive and use abundant sodium instead of scarce lithium. Although they function similarly, with charged sodium particles moving between two electrodes, they store less energy and degrade faster than lithium-ion models.

Researchers at the University of Surrey,  in England, discovered that sodium vanadium oxide performs significantly better when its naturally occurring water is left inside the battery instead of being removed during manufacturing. This simple modification nearly doubled the battery’s charge capacity, quickened charging and maintained stability over 400 charge-discharge cycles.

An additional bonus to leaving natural water inside sodium vanadium oxide is that the battery continues to function effectively within saltwater environments and is able to desalinate the seawater. Future systems might be able to provide cost-effective, dual-function units that provide sustainable energy storage and clean drinking water.