A low-cost and environmentally benign aqueous rechargeable sodium-ion battery based on NaTi2(PO4)3–Na2NiFe(CN)6 intercalation chemistry

• An aqueous rechargable Na-ion battery is developed.
• Na2NiFe(CN)6 and NaTi2(PO4)3 serve as cathode and anode, respectively.
• A Na2SO4 aqueous solution serves as the electrolyte.
• An output of ∼1.27 V and 42.5 Wh kg− 1 is achieved.
• This battery is safe, low cost and environmentally friendly.

An aqueous rechargable Na-ion battery is developed by use of Na-deficient NaTi2(PO4)3 anode, Na-rich Na2NiFe(CN)6 cathode and aqueous Na2SO4 electrolyte. This battery system can give an average output voltage of 1.27 V, a energy density of 42.5 Wh kg− 1 and can retain 88% of initial capacity for 250 cycles cycled at the 5 C rate. Moreover, this aqueous Na-ion battery has the advantages of low cost, environmentally friendliness and inherent safety, particularly attractive for grid-scale energy storage applications.

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