关键词: 过渡金属磷化物, 普鲁士蓝类似物, 碳限域, 异质界面, 锂离子电池负极

Transition metal phosphides (TMPs) are considered promising anode materials for lithium-ion batteries because of their high theoretical capacities and suitable operating potentials. Nevertheless, their practical application is still severely restricted by large volume fluctuation, particle pulverization, and sluggish charge-transfer/ion-diffusion kinetics during repeated lithiation and delithiation. In this work, a hierarchical carbon-confined bimetallic Fe-Ni-P heterostructure (Fe-Ni-P@C) was rationally constructed by using a Prussian blue analogue (Fe-Ni-PBA) as the precursor, followed by a dopamine-assisted coating strategy, carbonization, and phosphorization. Density functional theory calculations indicate that the introduction of Ni into the phosphide system increases the electronic states near the Fermi level, which is favorable for electronic transport. Structural characterization demonstrates that the obtained Fe-Ni-P@C composite preserves a uniform cubic morphology with an average particle size of about 120 nm, possesses a conductive carbon shell with a thickness of about 15 nm, and contains abundant internal voids and FeP/NiP₂ heterointerfaces. In addition, the material exhibits a high specific surface area of 798.24 m²•g⁻¹ with rich mesoporous features, which can effectively facilitate electrolyte penetration and provide sufficient electroactive sites. Benefiting from the synergistic effects of hierarchical porous architecture, conductive carbon confinement, and heterointerface engineering, the Fe-Ni-P@C electrode delivers a high specific capacity of 1025.4 mAh•g⁻¹ at 0.1 A•g⁻¹ and maintains 291.4 mAh•g⁻¹ after 1000 cycles at 2 A•g⁻¹. Electrochemical kinetic analyses further reveal that Fe-Ni-P@C possesses the lowest charge-transfer resistance, a Li⁺ diffusion coefficient of 5.58×10⁻¹⁰ cm²•s⁻¹, and a high pseudocapacitive contribution of 77.99% at 1.0 mV•s⁻¹, confirming its fast reaction kinetics and efficient charge-storage behavior. Furthermore, the assembled LiFePO₄//Fe-Ni-P@C full cell retains a discharge capacity of 113.2 mAh•g⁻¹ after 100 cycles and can successfully power a small blue LED. This study demonstrates that combining PBA-derived heterostructure design with dopamine-derived carbon confinement is an effective strategy for developing high-performance TMP-based anodes for advanced lithium-ion storage.

Key words: transition metal phosphides, Prussian blue analogues, carbon confinement, heterointerfaces, lithium-ion battery anodes