Synergistic intercalation–conversion reaction mechanism in Prussian blue analogue materials toward enhanced Na-storage

Abstract

Sodium-ion batteries (SIBs) have emerged as promising candidates for large-scale energy storage systems owing to the abundant and low-cost sodium resources. Among various cathode materials, Prussian blue analogues (PBAs) show great promise due to their three-dimensional open framework and easy synthesis process. However, critical challenges including limited electron transfer, blocked electronic pathways between particles, excessive lattice water content, and structural instability during cycling significantly compromise their electrochemical performance. Herein, we have developed a lead hexacyanoferrate/carbon nanotube composite (PbHCF/CNTs) through rational interface design to improve the electrochemical performance. The PbHCF/CNTs electrode exhibits a four-electron transfer capacity based on the redox reaction of Pb^0/2+ through a reversible intercalation–conversion mechanism. This innovative configuration delivers a high initial reversible capacity of 161.8 mA h g⁻¹ at 20 mA g⁻¹ and good cycling stability with 95.8 mA h g⁻¹ retained after 250 cycles at 100 mA g⁻¹ (64% capacity retention), along with enhanced structural reversibility confirmed by operando XRD analysis. This innovative approach provides a new design concept for high-capacity Prussian blue analogue cathode materials in the realm of high-performance SIBs and beyond.