Characteristics and electrochemical performances of silicon/carbon nanofiber/graphene composite films as anode materials for binder-free lithium-ion batteries

Abstract

We report the interfacial study of a silicon/carbon nanofiber/graphene composite as a potentially high-performance anode for rechargeable lithium-ion batteries (LIBs). Silicon nanoparticle (Si)/carbon nanofiber (CNF)/reduced graphene oxide (rGO) composite films were prepared by simple physical filtration and an environmentally-friendly thermal reduction treatment. The films were used as high-performance anode materials for self-supporting, binder-free LIBs. Reducing graphene oxide improves the electron conductivity and adjusts to the volume change during repeated charge/discharge processes. CNFs can help maintain the structural stability and prevent the peeling off of silicon nanoparticles from the electrodes. When the fabricated Si/CNF/rGO composites were used as anodes of LIBs, the initial specific capacity was measured to be 1894.54 mAh/g at a current density of 0.1 A/g. After 100 cycles, the reversible specific capacity was maintained at 964.68 mAh/g, and the coulombic efficiency could reach 93.8% at the same current density. The Si/CNF/rGO composite electrode exhibited a higher specific capacity and cycle stability than an Si/rGO composite electrode. The Si/CNF/rGO composite films can effectively accommodate and buffer changes in the volume of silicon nanoparticles, form a stable solid–electrolyte interface, improve the conductivity of the electrode, and provide a fast and efficient channel for electron and ion transport.

Synthesis and Electrochemical Performance of Electrostatic Self-Assembled Nano-Silicon@N-Doped Reduced Graphene Oxide/Carbon Nanofibers Composite as Anode Material for Lithium-Ion Batteries

“…However, the weight of pure nano-Si and composite materials significantly increased after 580 ℃. This is due to the difficulty of oxidation of the inside of Si nanoparticles and the formation of a small amount of SiO2 on the surface [40,41,49,50]. This is consistent with the results of XPS and FTIR.…”

“…The slanted line corresponds to the diffusion resistance of lithium ions within the electrode active material. The diffusion resistance is correspondingly expressed as Warburg impedance (ZW) [24,47,49]. As shown in the figure 8(d), the RCT of Si@N-doped rGO/CNF composite material is only 195.0 Ω, which is much lower than Si@Ndoped rGO composite material (295.6 Ω) and Si/rGO/CNF composite material (683.5 Ω).…”

“…The strong reduction peak around 0.01-1.2 V corresponds to the amorphous LixSi alloy formed by amorphous silicon during the reversible lithium-ion intercalation/deintercalation process. During the delithiation process, the two oxidation peaks at 0.35-0.37V and 0.52-0.55 V are attributed to the extraction of Li + from the lithium-silicon alloy, and the LixSi alloy decomposes into amorphous silicon [34,49]. In addition, as the number of scans increases, the intensity of the anode peak also gradually increases.…”

Synthesis and Electrochemical Performance of Electrostatic Self-Assembled Nano-Silicon@N-Doped Reduced Graphene Oxide/Carbon Nanofibers Composite as Anode Material for Lithium-Ion Batteries

“…However, the weight of pure nano-Si and composite materials significantly increased after 580 °C. This is due to the difficulty of oxidizing the inside of Si nanoparticles as well as the formation of a small amount of SiO 2 on the surface [ 34 , 41 , 49 ]. This is consistent with the XPS and FTIR results.…”

“…The strong reduction peak around 0.01–1.2 V corresponds to the amorphous LixSi alloy formed by amorphous silicon during the reversible lithium-ion intercalation/deintercalation process. During the delithiation process, the two oxidation peaks that can be seen at 0.35–0.37 V and 0.52–0.55 V are attributed to the extraction of Li + from the lithium-silicon alloy, while the LixSi alloy decomposes into amorphous silicon [ 19 , 49 ]. Further, as the number of scans increases, the intensity of the anode peak gradually increases as well.…”