Study On Prussian Blue Analogues Cathode Materials And Its Aqueous Zinc Ion Batteries

In recent years,rechargeable lithium-ion batteries have been widely used in many fields,such as electric vehicle,portable electronic products and energy storage devices.However,the security issues,high-cost and relative scarcity of lithium restrict the its application in certain aspects.Therefore,searching for a lower cost and safer alternatives is concerned.Because of low-cost and large reserves of Zn element and metallic zinc is regarded as an ideal anode material for aqueous batteries due to its high theoretical capacity(820 m A h g^–1)with two charge transfer,low electrochemical potential(-0.762 V versus the standard hydrogen electrode(SHE))and a non-toxicity,intrinsic safety aqueous electrolyte in nature,so Zn-ion batteries(ZIBs)are regarded as promising candidates for low-cost and large-scale energy storage.In this paper,we focus on the cathode of aqueous zinc-ion battery,research on Prussian blue analouges(PBA).The main research work is as follows:(1)Prussian blue analogues are considered ideal cationic matrix materials due to their unique open frame structure.In this paper,a series of different types of Prussian blue analogues were synthesized by various methods,and their differences in morphology,structure,and electrochemical properties were compared respectively.Ni HCF(Ni HCF-n)was selected as the main research object to test the electrochemical performance of Ni HCF in different electrolytes.The electrochemical performance of Ni HCF varies greatly in different electrolyte systems.In 1 M Zn(TFSI)₂ and 1 M Zn SO₄ low concentration aqueous electrolytes,the cycle performance is poor and the capacity decay is fast,while in 1 M Zn(TFSI)₂+21 M Li TFSI high concentration aqueous electrolyte and organic electrolyte(0.5 M Zn(Cl O₄)₂ dissolved in acetonitrile)have completely different performances,especially in high concentration aqueous electrolytes,not only stable cycling performance,high capacity retention rate,The number of cycles is more than 1600 times,and the capacity is up to 60.2 m Ah/g.(2)Employing XPS and XRD to study the evolution of Ni HCF electrode after cycling in different electrolytes in details.Ni HCF decomposes seriously in the low-concentration electrolyte,producing a new phase Zn₂Fe(CN)₆,and the substance is electrochemically inert,and the high water content of the dilute aqueous solution causes the dissolution of Ni.The capacity in the low concentration aqueous electrolyte decays rapidly,on the contrary,the Ni HCF phase remains relatively intact after cycling in the high-concentration electrolyte,so Ni HCF can exhibit excellent electrochemical performance in the high-concentration electrolyte.