Dual-active CoFe@NCNT nanohybrids: synergistic encapsulation via nitrogen-rich precursors for high-capacity freestanding lithium-ion anodes

Abstract

Addressing the capacity degradation challenge in carbon nanotube-based anode materials, this study 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 capability to produce nitrogen-rich products 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 a full-cell configuration, the system achieves 84.8% capacity retention over 550 cycles at a 1C rate, demonstrating its potential for practical applications. This work provides novel insights into interface engineering for designing highly stable metal–carbon composite electrodes.