High sodium content Prussian White (PW) powder is a cathode material for the next generation of environmentally friendly sodium ion batteries. Composition is NaxFe[Fe(CN)6] with x>1.9. This material is ideal as performance positive electrode in sodium-ion batteries and can be paired against anode materials which do not contain sodium. Ideal storage is under inert conditions in order to maintain quality over the longer term. Nominal voltage 3.25 V on average, capacity ~160 mAh g-1.