Three-dimensionally structured silicon (Si)–carbon (C) nanocomposites have great potential as anodes in lithium-ion batteries (LIBs). Here, we report a Nitrogen-doped graphene/carbon-encapsulated Si nanoparticle/carbon nanofiber composite (NG/C@Si/CNF) prepared by methods of surface modification, electrostatic self-assembly, cross-linking with heat treatment, and further carbonization as a potential high-performance anode for LIBs. The N-doped C matrix wrapped around Si nanoparticles improved the electrical conductivity of the composites and buffered the volume change of Si nanoparticles during lithiation/delithiation. Uniformly dispersed CNF in composites acted as conductive networks for the fast transport of ions and electrons. The entire tightly connected organic material of NG/C@Si and CNF prevented the crushing and shedding of particles and maintained the integrity of the electrode structure. The NG/C@Si/CNF composite exhibited better rate capability and cycling performance compared with the other electrode materials. After 100 cycles, the electrode maintained a high reversible specific capacity of 1371.4 mAh/g.

By powering sophisticated lithium-ion batteries (LIBs), silicon/carbon (Si/C) composites have the potential to accelerate the sustainable energy transition. This is a first-of-its-kind Si/C hybrid with hydroxyl-functionalized graphene quantum dots (OH-GQD) electrostatically assembled within interconnected reduced graphene oxide networks (OH-GQD@Si/rGO) prepared through solution-phase ultrasonication and subsequent one-step, low-temperature annealing and thermal reduction. The OH-GQD@Si/rGO hybrid utilized as the LIB anode delivered a high initial specific capacity of 2,229.16, 1,303.21, and 1,090.13 mAh g−1 reversible capacities at 100 mA g−1 after 50 and 100 cycles, and recovered 1,473.28 mAh g−1 at rates as high as 5 A g−1. The synergistic benefits of the OH-GQD/rGO interface give dual, conductive carbon protection to silicon nanoparticles. Consecutive Si surface modifications improved Si–rGO contact modes. The initial OH-GQD carbon coating increased storage capacity through vacancy defects changing the electron density in the lattice, whereas hydroxyl functionality at the edges acted as active storage sites. Secondary protection through rGO encapsulation improved Si conductivity and usage by providing continuous electron/ion routes while minimizing Si volume variations. The proposed OH-GQD/rGO hybridization as a dual-carbon protection strategy to Si stabilized the solid electrolyte interface leading to electrode stability. This work is expected to advance the development of next-generation Si-based LIB anodes.

Si is a next‐generation ideal anode material for Li‐ion batteries (LIBs) because of its high‐theoretical capacity (4200 mAh/g) and natural abundance. However, severe volume expansion and unstable solid electrolyte interface (SEI) film formation during lithiation/delithiation, and poor electron conductivity have significantly restricted the commercial application of Si. In this study, transition metal‐coated Si was synthesized and used as the anode material of LIBs. The transition metal salt of Ni was dissolved in an aqueous solution and used to coat the metal surface of Si nanoparticles. The coating was achieved by dropwise addition of metal solutions into Si dispersions. Thereafter, carbon nanofibers (CNFs) were grown on the transition metal‐coated Si nanoparticles via chemical vapor deposition method. The morphologies, compositions, and crystal quality of transition metal@Si/CNFs composites were characterized by transmission electron microscopy, scanning electron microscopy, x‐ray diffraction, Raman spectroscopy, and thermogravimetric analysis. The electrochemical characteristics of the hybrid anodes were investigated using a coin cell and battery tester. Voltage profile measurements at 0.1 A/g of 0.02 M‐Ni@Si/CNFs composite showed satisfactory initial Coulombic efficiency of 85.6%; 0.01 M‐Ni@Si/CNFs composite exhibited high initial capacity of 1300.9 mAh/g retained to 828.4 mAh/g after 100 cycles, corresponding to 63.7% capacity retention. Even at high current densities, the 0.02 M‐Ni@Si/CNFs composite delivered 342.78 mAh/g of capacity at 5 A/g. This work realizes a Si‐based hybrid anode from Ni‐coated Si catalyst used for direct CNFs synthesis with a stable SEI layer, superior initial Coulombic efficiency with satisfactory cycle and rate performance suitable for commercialized advanced battery applications.

Three-dimensionally structured silicon (Si)-carbon (C) nanocomposites have great potential as anodes in lithium-ion batteries (LIBs). Here, we report a Nitrogen-doped graphene/carbon-encapsulated Si nanoparticle/carbon nanofiber composite (NG/C@Si/CNF) prepared by methods of surface modification, electrostatic self-assembly, cross-linking with heat treatment, and further carbonization as a potential high-performance anode for LIBs. The N-doped C matrix wrapped around Si nanoparticles improved the electrical conductivity of the composites and buffered the volume change of Si nanoparticles during lithiation/delithiation. Uniformly dispersed CNF in composites acted as conductive networks for the fast transport of ions and electrons. The entire tightly connected organic material of NG/C@Si and CNF prevented the crushing and shedding of particles and maintained the integrity of the electrode structure. The NG/C@Si/CNF composite exhibited better rate capability and cycling performance compared with the other electrode materials. After 100 cycles, the electrode maintained a high reversible specific capacity of 1,371.4 mAh/g.