Prussian white analogues as promising cathode for non-aqueous potassium-ion batteries

• We introduce Prussian white analogues, KxMy[Fe(CN)6]z (M = Fe, Co, Ni, Cu), as cathode materials for potassium-ion batteries.
• All these Prussian white materials exhibit high reaction potential, promising capacity and cycling performance.
• K1.68Fe1.09Fe(CN)6·2.1H2O delivers high discharge potentials, high capacity of 110 mAh g− 1, and excellent cycling life.

We prepared Prussian white analogues—KxMFe(CN)6·mH2O (M = Fe, Co, Ni, or Cu). These compounds are investigated as cathode materials for potassium-ion batteries with a non-aqueous electrolyte. Each of these materials exhibits different K-ion storage properties with reversible capacity values ranging from 35 to 110 mAh g− 1 at high potentials above 3.2 V vs. K+/K. Among them, FeFe-Prussian white, K1.68Fe1.09Fe(CN)6·2.1H2O, exhibits the highest reversible capacity of 110 mAh g− 1 and stable cycling performance in contrast to rapid capacity fading of other analogues. Our results demonstrate a remarkable potential of this family of cathode materials for the emerging potassium-ion batteries.

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