Dual-Active CoFe@N-CNTs Nanohybrids: Synergistic Encapsulation via Nitrogen-Rich Precursors for High-Capacity Freestanding Lithium-Ion Anodes

Addressing the capacity degradation challenge in carbon nanotube-based anode materials, this study novel proposes a synergistic strategy integrating 3D conductive network construction with robust metal-carbon coupling interfaces. By selecting dicyandiamide (DCDA) as an optimal carbon/nitrogen precursor and combining solvothermal synthesis with chemical vapor deposition (CVD), we achieved in-situ growth of nitrogen-doped carbon nanotubes and uniform anchoring of Co-Fe nanoparticles. Pyrolysis characterization reveals that the DCDA system exhibits superior thermal stability and nitrogen-rich capability compared to cyanamide (CA) and melamine (MA) counterparts. Benefiting from the synergistic effects between the 3D conductive network and metal active sites, the CoFe@NCNTs/CC(DCDA) anode demonstrates exceptional lithium storage performance: delivering a high specific capacity of 1717.6 mAh·g⁻¹ at 1 A·g⁻¹ with 93.6% capacity retention after 250 cycles, while maintaining 1413.1 mAh·g⁻¹ at an elevated current density of 2 A·g⁻¹. When paired with NCM811 cathodes in full-cell configuration, the system achieves 84.8% capacity retention over 550 cycles at 1C rate, demonstrating its potential for practical applications. This work provides novel insights into interface engineering for designing highly stable metal-carbon composite electrodes.