The potassium energy storage behavior of Nickel-Znic co-doped Prussian blue analogs formed by a chelating agent assisted route and its application in a K+-proton hybrid ions aqueous alkaline Battery

A serials of nickel-zinc hexacyanoferrate (NixZnyHCF) are synthesized through a conventional co-precipitation method and the potassium ion storage performances are tested in 30% KOH solution. Among those samples, the Ni3Zn1HCF obtained the highest capacity. (96.7mAh g-1) After introducing the chelating agent into the synthesis procedure, the obtained Ni3Zn1HCF-10 displayed the high crystallinity with reduced crystal water and demonstrated the improved cyclic stability (99.0 % capacity retention after 350 cycles) over the sample without chelating agent involving. (56.2% capacity retention after 250 cycles) Finally, a K+/H+ hybrid ion aqueous alkaline battery was built by Ni3Zn1HCF-10 cathode and active carbon anode. The constructed full cell delivered a capacity of 44.8 mAh g-1 with 1.6 V operational voltage. Further, it had excellent rate capability and low self-discharge along with good stability (99.6% capacity retention after 500 cycles). This work expands a great strategy for aqueous rechargeable alkaline batteries.