Improvement in cycling stability of Prussian blue analog-based aqueous sodium-ion batteries by ligand substitution and electrolyte optimization

• Published in: Electrochimica acta Vol. 427; p. 140778
• Main Authors: Pan, Tsung-You, Ruqia, Wu, Cheng-Yen, Ni, Chung-Sheng, Gull, Sanna, Haider, Ali, Chen, Han-Yi
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20.09.2022
• Subjects: Aqueous sodium-ion batteries; In situ synchrotron X-ray diffraction; Ligand-modified; Prussian blue analog; X-ray absorption spectroscopy; Aqueous sodium-ion batteries; X-ray absorption spectroscopy; Prussian blue analog; In situ synchrotron X-ray diffraction; Ligand-modified
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2022.140778

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, NaxCu[Fe(CN)5(C6H4N2)] (NaxCuCNPFe), and NaxCu[Fe(CN)5(CH3C6H4NH2)] (NaxCuTolFe) were tested in different electrolytes. The NaxCuCNPFe and NaxCuTolFe cathodes exhibited the best capacity retention of ∼50% after 2000 cycles in 1 M Na2SO4, 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 NaxCuCNPFe//NTP@C@RGO and NaxCuTolFe//NTP@C@RGO full cells in 17 m NaClO4 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.