Prussian blue analogue derived bimetallic phosphide for high areal capacity and binder-free sodium-ion battery anode

Prussian blue analogues (PBAs) derived materials are widely concerned due to their diversity, porous structures, multiple active sites of metal-organic frameworks, as well as the facile synthesis process. In this work, the Cu–PBAs grow in-situ on Titanium (Ti) net, and then the Cu₃P and Fe₂P materials (Cu–Fe–P/TiN) is prepared with subsequent phosphorization, which can be used as binder-free and conductive agent-free anode for sodium-ion batteries. And the Cu–Fe–P is closely linked with Ti net to form a conductive network by regular rod-like particles, which contributes to the excellent electrochemical performance. The Cu–Fe–P/TiN can deliver a high reversible capacity of more than 180 mAh g⁻¹ at 50 mA g⁻¹, and achieve a capacity retention rate of 70% after 100 cycles. At areal current density of 1 mA cm⁻², the reversible capacity of the Cu–Fe–P/TiN electrode is 1.6 mAh cm⁻². The reversible transformation and sodium storage mechanism are further revealed by in-situ characterizations.