Optimizing the electrolyte and binder composition for Sodium Prussian Blue, Na1-xFex+(1/3)(CN)6·yH2O, as cathode in sodium ion batteries

• Sodium Prussian Blue (Na-PB) is used as cathode in sodium ion batteries (NIB).
• Several electrolytes and binders are electrochemically tested for Na-PB.
• 1 M NaPF6 in EC: PC: FEC can be established as standard electrolyte for Na-PB.
• PVDF is the advisable binder for Prussian Blue cathode materials in NIB.

Na-ion batteries (NIB) are now attracting researchers’ attention as possible substitutes of Li-ion batteries. Promising cathode materials, which have demonstrated to work well for NIB are those based on the sodiated Prussian Blue, NaFeFe(CN)6, Prussian White, Na2FeFe(CN)6, and their analogues. Herein, the effect of different electrolytes and binder composition, on the electrochemical performance of sodium Prussian Blue, Na0.75Fe2.08(CN)6·3.4H2O, as cathode material for NIB is studied. Several electrolytes containing NaClO4 or NaPF6 salts in carbonated mixtures, with and without fluoroethylene carbonate (FEC) as additive, have been tested for Na0.75Fe2.08(CN)6·3.4H2O. The effect of different binders, polyvinylidene fluoride (PvdF), sodium carboxymethyl cellulose (CMC), polytetrafluoroethylene (PTFE) and ethylene propylene diene monomer ruber (EPDM), is also investigated.

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