Optimization Of Prussian Blue Materials And Their Performance Studies For Sodium-ion Batteries

Prussian blue(PB)materials and Prussian blue analogs(PBAs)are ideal for sodium ion batteries because of their unique structure,high theoretical capacity,long cycle life and high rate performance.This work aims to reduce the defects of Prussian blue material and prepare materials with high crystallinity for sodium ion batteries.Firstly,a feasible route combining controllable electrodeposition and co-deposition is designed to prepare high performance Co-HCF@CFCs.Comparative analysis revealed that Co-HCF@CFCs has the best performance for sodium ion battery.At the current density of1.0 Ag^-1,it deliver a capacity of 92 m Ahg^-1.CV and GITT of Co-HCF@CFCs demonstrated the fast diffusion kinetics and high diffusion coefficient.Flexible aqueous battery based on Co-HCF@CFCs also exhibit excellent performance at high bending angles(180°).The advantages of Co HCF make it have good promising applications in large-scale energy storage systems.Secondly,since the sodium ion batteries have the advantage of high specific capacity,while zinc metal anode has the advantages of low cost and high stability.Dual-ion batteries can take advantage of both sodium and zinc ion batteries using the electrolyte of zinc sulfate(0.33 M)and sodium sulfate(0.33 M)solution.The dual-ion battery deliver a capacity of80 m Ah g^-1 at the current rate of 1.0 A g^-1,and the capacity remains 75 m Ah g^-1 after 400cycles with a capacity retention rate of 93%.Thirdly,the vacancy and coordination water in PBAs can be reduced via slow nucleation.Firstly,(Fe_xMn_3-x)Fe(CN)₆ was synthesized by simple modified co-precipitation method.Then Na₂(Fe_xMn_3-x)Fe(CN)₆ nanometer materials were prepared by the Na I chemical reduction method.The resulting high crystallinity Na₂(Fex Mn_3-x)Fe(CN)₆nanocrystals shows extremely high electrochemical activity because of the high crystallinity and low defect.The organic sodium ion battery shown a capacity of 88 m Ah g^-1 at the current density of 0.02 A g^-1.