Three-dimensional network of nitrogen-doped carbon matrix-encapsulated Si nanoparticles/carbon nanofibers hybrids for lithium-ion battery anodes with excellent capability

Abstract

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.

Si@C Core–Shell Nanostructure-Based Anode for Li-Ion Transport

“…This leads to the graphitization of the carbon shell, resulting in improved conductivity. , The active groups (highly electronegative group) also attract lithium ions, reducing the energy barrier for lithium ion intercalation. Furthermore, the introduction of vacancies and defects into the original carbon structure increases the diffusion rate of lithium ions. , …”

“…Furthermore, the introduction of vacancies and defects into the original carbon structure increases the diffusion rate of lithium ions. 21,22 In order to understand the electrochemical performance of the anode material, the cyclability of the Si anode and the p-Si@C anode were tested under the terminating condition of 0.01 to 3 V relative to Li/Li + at a current density of 60 mA g −1 . As shown in Figure 5a, the initial Coulombic efficiency of the Si anode is 62%, while the reversible capacity is 63 mAh g −1 , which is due to the large volume change during cycling, which causes particle collapse and leads to low capacity.…”

“…According to their results, a higher doped nitrogen ratio improved the rate performance and increased the maximum specific capacity. Therefore, in this work, we used p -phenylenediamine (PPD) containing nitrogen (see Figure ) as the carbon source to form the shell around the nanosized silicon particles, including the possible mechanism of nitrogen in affecting the lithium ion diffusion, which was also further analyzed. , The p-Si@C nanocomposite exhibited a uniform and ultrathin amorphous carbon shell (about 5 nm). From the presented results, it is clear that the ICE can be pushed up to 84%.…”

Constructing a Stable Integrated Silicon Electrode with Efficient Lithium Storage Performance through Multidimensional Structural Design

“…Carbon nanotubes (CNT) are also employed due to their high aspect ratio, excellent conductivity, and high mechanical strength. Encapsulation of CNT on the outer surface of Si through electrostatic self-assembly, , electrostatic adsorption, or in situ growth − methods achieves a comparable effect to that of an elastic carbon layer. Researchers have also adopted a skin-like covalent encapsulation strategy to create two-dimensional covalent Si/C materials, which exhibit high stability, capacity, and rate capability.…”

Carbon Nanofiber Cages and Interface Engineering Stabilizing Silicon-Based Anode for High-Performance Lithium-Ion Batteries

“…The Si-CNF@C composites showed excellent electrochemical properties. Cong et al 19 prepared NG/C@Si/CNF composites by a multistep thermal treatment process. After 100 cycles at 0.1 A g −1 , the NG/C@Si/CNF composite demonstrated a reversible capacity of 1371.4 mA h g −1 .…”