Flexible self-supporting CoNi alloy-doped carbon nanofibers with uniformly dispersed nanoparticles: a 3D host for stable lithium metal anodes†

Abstract

Utilizing lithophilic sites to guide the uniform deposition of lithium is an effective strategy to inhibit the disordered growth of lithium. However, current strategies relying on monometallic doping (e.g., Fe, Sn, and Cu) often struggle to control lithium dendrite growth and maintain stable interfacial chemistry. In situ formation of alloy nanoparticles within carbon hosts has emerged as a promising approach. In this study, we present a facile electrospinning strategy to fabricate flexible carbon nanofibers doped with in situ formed uniformly dispersed CoNi alloy nanoparticles, which serve as 3D hosts for lithium metal anodes. The uniform dispersion of CoNi nanoparticles in the carbon matrix modulates the surface electron density and promotes the formation of lithophilic pyrrolic-N and Co/Ni–N_x bonds. DFT calculations and in situ characterization confirm their role in guiding the dense deposition of lithium. This allows its lifespan to reach over 1000 h at 10 mA cm⁻² with a tiny voltage hysteresis of 130 mV. When coupled with a LiFePO₄ cathode, the anode-less full cell maintains an excellent specific capacity of 131.3 mAh g⁻¹ and an impressive coulombic efficiency of 99.3% after 700 cycles at 1C. This work paves a new avenue for designing advanced bimetallic alloy-doped carbon frameworks with synergistic defect engineering and porosity.