Achieving Long-Cycle-Life Zinc-Ion Batteries through a Zincophilic Prussian Blue Analogue Interphase

Abstract

The practical application of rechargeable aqueous zinc-ion batteries (ZIBs) has been severely hindered by detrimental dendrite growth, uncontrollable hydrogen evolution, and unfavorable side reactions occurring at the Zn metal anode. Here, we applied a Prussian blue analogue (PBA) material K₂Zn₃(Fe(CN)₆)₂ as an artificial solid electrolyte interphase (SEI), by which the plentiful -C≡N- ligands at the surface and the large channels in the open framework structure can operate as a highly zincophilic moderator and ion sieve, inducing fast and uniform nucleation and deposition of Zn. Additionally, the dense interface effectively prevents water molecules from approaching the Zn surface, thereby inhibiting the hydrogen-evolution-resultant side reactions and corrosion. The highly reversible Zn plating/stripping is evidenced by an elevated Coulombic efficiency of 99.87% over 600 cycles in a Zn/Cu cell and a prolonged lifetime of 860 h at 5 mA cm^-2, 2 mAh cm^-2 in a Zn/Zn symmetric cell. Furthermore, the PBA-coated Zn anode ensures the excellent rate and cycling performance of an α-MnO₂/Zn full cell. This work provides a simple and effective solution for the improvement of the Zn anode, advancing the commercialization of aqueous ZIBs.

Keywords: Prussian blue analogues; Zn anode; aqueous zinc-ion batteries; artificial SEI layer.

Figure 1

(a) The synthesis path and on-site deposition of PBA on the Zn foil, (b) The optical image of bare Zn, (c) The optical image of the Zn covered with a PBA layer, (d) The top and (e) cross-sectional SEM images of the PBA@Zn, (f) XRD patterns of bare Zn, PBA@Zn, and PBA, (g) FT-IR spectrum of PBA layer.

Figure 2

(a) Cycling performance of bare Zn and PBA@Zn at 5 mA cm⁻², 2 mAh cm⁻² in symmetric cells, (b) Coulombic efficiencies of Zn/Cu with or without coating at 5 mA cm⁻² and 2 mAh cm⁻², (c,d) Voltage profiles of Zn/Cu cells with or without coating at 5 mA cm⁻², 2 mAh cm⁻², (e,f) Rate performance at 1, 2, 5, and 10 mA cm⁻², 2 mAh cm⁻² in symmetric cells.

Figure 3

(a) The SEM image of bare Zn soaked in 2M ZnSO₄ for 72 h, (b) The SEM images of PBA@Zn soaked in 2M ZnSO₄ for 72 h, (c) XRD patterns of bare Zn foil and PBA@Zn after corrosion in 2M ZnSO₄ for 72 h, (d) LSV characterization of Zn/Ti cells, (e) CA characterization of Zn/Zn cells, (f) The initial nucleation overpotential of Zn/stainless steel cells.

Figure 4

(a–d) The optimized H₂O and Zn²⁺ adsorbed configurations, (e) Binding energies of Zn²⁺ and H₂O on the Zn-(002) and PBA-(002) plane, (f) Schematic Zn²⁺ deposition on PBA@Zn electrode.

Figure 5

(a) CV profiles of the Zn/α-MnO₂ cells and PBA@Zn/α-MnO₂ cells, (b) Electrochemical impedance spectroscopy (EIS) data of Zn/α-MnO₂ cells and PBA@Zn/α-MnO₂ cells, (c) Charge−discharge curves of the Zn/α-MnO₂ cells and PBA@Zn/α-MnO₂ cells, (d) Rate performance of the Zn/α-MnO₂ cells and PBA@Zn/α-MnO₂ cells, (e) Charge-discharge profile of the PBA@Zn/α-MnO₂ cells at different current densities, (f) Cycling performance of Zn/α-MnO₂ and PBA@Zn/α-MnO₂ cells at 1 A g⁻¹.