摘要
In this study, we investigated the effects of ligand substitution in Prussian blue analog (PBA) cathode materials on the performance of aqueous sodium-ion batteries. NaCu[Fe(CN) 6 ] (NaCuHCF) and ligand-modified PBAs, Na x Cu[Fe(CN) 5 (C 6 H 4 N 2 )] (Na x CuCNPFe), and Na x Cu[Fe(CN) 5 (CH 3 C 6 H 4 NH 2 )] (Na x CuTolFe) were tested in different electrolytes. The Na x CuCNPFe and Na x CuTolFe cathodes exhibited the best capacity retention of ∼50% after 2000 cycles in 1 M Na 2 SO 4 , which is much higher than that of the NaCuHCF cathode (0% capacity remained after 2000 cycles). To understand the charge–discharge mechanism of PBA cathodes, in situ synchrotron X-ray absorption spectroscopy and X-ray diffraction were performed. To demonstrate practical energy storage applications, PBAs were tested in full-cell configurations with an anode made of sodium titanium phosphate (NTP) coated with reduced graphene oxide and carbon (NTP@C@RGO). The Na x CuCNPFe//NTP@C@RGO and Na x CuTolFe//NTP@C@RGO full cells in 17 m NaClO 4 aqueous electrolyte exhibited high power densities of up to 4338 W kg −1 (with an energy density of 18.11 Wh kg −1 ) and 4742 W kg −1 (with an energy density of 11.87 Wh kg −1 ), respectively. Our study demonstrates the potential of optimizing organic ligands in PBAs and electrolytes for the improvement of the cycling stability of high-power aqueous sodium-ion batteries.