Carbon Nanofiber Composites Research Articles

Prussian blue analogue-derived Co-Ni5P4 porous nanosheet arrays composite coal-based carbon nanofibers as efficient self-supported electrocatalyst for overall water splitting

The development of economical, earth-rich, and high-performance transition metal phosphides electrocatalysts is crucial for water splitting. Herein, the NiCo PBA/Ni(OH)2 hierarchical nanostructure arrays are in situ grown on the coal-based carbon nanofibers (C-CNFs) using hydrothermal and co-precipitation methods. Subsequently, the Co-doped Ni5P4 porous nanosheet arrays composite coal-based carbon nanofibers electrocatalyst (Co-Ni5P4@C-CNFs) is obtained through low-temperature phosphorization process. Benefiting from cation-doped, porous nanosheet arrays structure and self-supported conductive substrates, the Co-Ni5P4@C-CNFs has excellent electrocatalytic performance for overall water splitting. It provides low overpotentials of 75 mV for hydrogen evolution reaction (HER) and 231 mV for oxygen evolution reaction (OER) to achieve the current density of 10 mA cm−2 in 1 M KOH electrolyte. Furthermore, the Co-Ni5P4@C-CNFs demonstrates a low overall water splitting cell voltage of 1.537 V at current density of 10 mA cm−2 and remarkable long-term stability for over 160 h. It outperforms the most transition metal phosphide bifunctional electrocatalysts reported to date. This research provides a novel strategy for synthesizing high-performance transition metal phosphides bifunctional electrocatalysts.

Facile design and permittivity regulation of porous carbon and magnetic particles based composite nanofibers towards highly efficient electromagnetic wave absorption

Two kinds of porous carbon and magnetic particles-based composite nanofibers (PCNTF-CoFe and PCNTF-NiFe) were synthesized for electromagnetic wave (EMW) absorption. Magnetic particles were used as the catalyst to increase the crystallinity of carbon and the corresponding dielectric loss ability, while porous structure was designed to improve the impedance matching. According to the results, the dielectric loss abilities of PCNTF-CoFe and PCNTF-NiFe are enhanced without significant degradation in their impedance matching condition. Therefore, through the polarization and conduction-induced dielectric loss together with the natural and exchange resonance-induced magnetic loss, the incident EMW can be attenuated rapidly inside PCNTF-CoFe and PCNTF-NiFe. PCNTF-CoFe shows a minimum reflection loss (RLmin) of −54.6 dB and effective band width (RL≤-10 dB, EABW) of 6.0 GHz at 2.0 mm, while PCNTF-NiFe shows RLmin of −33.4 dB and EABW of 5.7 GHz at 1.7 mm. Consequently, PCNTF-CoFe and PCNTF-NiFe can be promising candidates for application in EMW absorption.

Preparation and Electrochemical Performance of Activated Composite Carbon Nanofibers Using Extraction Residue from Direct Coal Liquefaction Residue

Organic carbon extracted from direct coal liquefaction residue (DLCR) is an ideal precursor for the preparation of carbon materials. However, investigations into the utilization of the extraction residue (ER) are rarely reported. In this work, ER from DCLR was pretreated with H2O2 to afford oxidized extraction residue (OER). Then, the OER was mixed with polyacrylonitrile (PAN) in N,N-dimethylformamide for the preparation of composite carbon nanofibers by electrospinning. With adding 80 wt.% OER, the composite carbon nanofibers still demonstrate a clear fiber profile and smooth surface under a scanning electron microscope, indicating that the OER has good solubility with PAN in N,N-dimethylformamide. The electrochemical performance characterization of the activated composite carbon nanofiber shows that the P-OER60-AC (activated composite carbon nanofibers prepared with 60 wt.% of OER and 40 wt.% of PAN) has a better electrochemical performance with a specific capacitance of 97 F/g at 0.5 A/g, as compared to the others. Additionally, the P-OER80-AC (activated composite carbon nanofibers prepared with 80 wt.% of OER and 20 wt.% of PAN) is also considerable for the perspective of coal-based solid waste treatment and utilization.

Improved performance of lithium–sulfur battery with a free-standing cobalt-doped vanadium nitride carbon nanofiber interlayer

Lithium–sulfur batteries (LSBs) are considered promising devices for next-generation secondary battery owing to their low cost and high energy density. However, the practical application of LSB is hindered by the sluggish redox kinetics of sulfur and the shuttling effect of polysulfide. To address the above problems, cobalt-doped vanadium nitride/three-dimensional carbon nanofiber (Co-VN/3DNC) composites were synthesized based on non-woven fabrics. The Co-VN/3DNC interlayer can serve as a physical barrier directly for the shuttle effect alleviating in LSBs. The introduction of the Co atom can enrich the d-electron number of VN, improving the catalysis of LSBs redox reaction. The growth of curved carbon nanotubes (CNTs) on the surface of the intermediate layer can expose active adsorption-catalytic sites, accelerating polysulfide redox kinetics for LSBs. The electrochemical performance of the LSB is greatly enhanced by the synergistic effect of Co, VN, and 3DNC. The LSB with Co-VN/3DNC interlayer demonstrate a capacity of 1207.7 mAh g−1 at a current density of 0.1C, and retain a specific capacity of 918.2 mAh g−1 even after 250 cycles. This work provides an effective strategy for the intermediate layers design to improve the electrochemical performance of LSBs.

Boosting energy harvesting of fully flexible magnetoelectric composites of PVDF-AlN and NiO-decorated carbon nanofibers

The increasing popularity of wearable electronics has sparked interest in flexible energy harvesters as alternatives to conventional batteries. Flexible magnetoelectric (ME) composites, known for converting ambient magnetic field energy into useable power, are emerging as promising autonomous energy sources for integration into wearable devices. In this study, we prepared flexible (PVDF-AlN)–(NiO–CNF) based ME composites using two different methods: solution-casting and electrospinning techniques. The ME coupling was confirmed by measuring the ferroelectric and magnetic properties of the composite, and it was qualitatively characterized through the ME coupling coefficient. The electrospinning fibers-based ME composite exhibited an optimal value of 10.6 V/cm.Oe, significantly higher than the solution-casting films-based ME composite (1.3 V/cm.Oe) under a 1 kHz AC magnetic field (off-resonance condition). Subsequently, a flexible magneto-mechano-electric (MME) generator was designed using electrospun-derived material, harvesting a sinusoidal wave with a maximum output peak-to-peak voltage of 9.02 V. The generator displayed an optimal DC power density of 97 μW/m2 when exposed to a weak AC magnetic field of 6 Oe at a frequency of 50 Hz. Consequently, it holds great promise as an efficient autonomous power supply for medical sensing and various miniature electronic applications.

Enhancing metronidazole photodegradation through the application of dysprosium vanadate/oxidized carbon nanofiber composite

The widespread usage of nitroimidazole antibiotics, including metronidazole (MD), and the improper disposal of pharmaceutical residues in groundwater samples pose a significant health risk due to the potential carcinogenic and mutagenic toxicity. Our research engineered a nanocomposite by combining dysprosium vanadate with oxidized carbon nanofibers (DyVO4/O-CNF) through coprecipitation, acid treatment, and ultrasonication methods. We meticulously examined these prepared nanocomposites using various spectroscopic and microscopic techniques, revealing enhanced characteristics in crystallinity, active vibrational bands, valence states, band gap, and structural morphology. To assess the photocatalytic efficacy of DyVO4/O-CNF nanocomposite for degrading MD, we performed a series of photocatalytic experiments. These included optimizing the dosage, analyzing MD concentration, studying the influence of radical scavengers, and examining the mineralization process along with the potential photodegradation mechanism. Our findings demonstrated that the DyVO4/O-CNF nanocomposite (98.7 % within 40 min) surpassed other catalysts such as TiO2 (26.1 %), pristine CNF (40.3 %), and DyVO4 (59.6 %). Furthermore, we evaluated the nanocomposite's stability and reusability, revealing a consistent photodegradation efficiency of 94.7 % even after five consecutive cycles. These findings highlight the efficacy of the DyVO4/O-CNF nanocomposite as a highly effective catalyst for the photodegradation of MD.

Preparation of Zeolitic Imidazolate Framework and Carbon Nanofiber Composites for Nitrofurazone Detection

Metal–organic frame (MOF) materials may have the advantages of a regular pore structure, large porosity, and large specific surface area, which could provide better catalytic activity, but they have some disadvantages in electrocatalysis. In contrast, carbon nanofibers (CNFs) prepared by electrospinning methods have good conductivity and stability. Therefore, this research aimed to generate MOF/CNFs composite materials to improve the electrochemical properties of MOF materials and apply them to the field of electrochemical sensing. This experiment was based on the preparation of straight unidirectional CNFs by an electrospinning method at 2000 RPM. The original method of preparing zeolitic imidazolate frameworks (ZIF-8) was improved and ZIF-8 was uniformly dispersed on the surface of CNFs to form a ZIF-8/CNF composite with a fiber diameter of about 0.10 to 0.35 µm. The specific surface area of the CNFs was about 42.28 m2/g, while that of the ZIF-8/CNF composite was about 999.82 m2/g. The specific surface area of the ZIF-8/CNF composite was significantly larger than that of CNFs. The GCE/ZIF-8/CNF electrode had an excellent electrochemical reaction, with an oxidation peak at about 216 μA, which proved that the ZIF-8/CNF composite material would have good catalytic activity and excellent electrochemical properties for the detection of nitrofurazone compared to other modified electrodes.

SAXS unveils porous anodes for potassium-ion batteries: dynamic evolution of pore structures in Fe@Fe2O3/PCNFs composite nanofibers.

The porous structure of composite nanofibers plays a key role in improving their electrochemical performance. However, the dynamic evolution of pore structures and their action during ion intercalation/extraction processes for negative electrodes are not clear. Herein, porous carbon composite nanofibers (Fe@Fe2O3/PCNFs) were prepared as negative electrode materials for potassium-ion batteries. Electrochemical test findings revealed that the composites had good electrochemical characteristics, and the porous structure endowed composite electrodes with pseudo-capacitive behaviors. After 1500 discharge/charge cycles at a current density of 1000 mA g-1, the specific capacity of the potassium-ion batteries was 144.8 mAh g-1. We innovatively used synchrotron small-angle X-ray scattering (SAXS) technique to systematically investigate the kinetic process of potassium formation in composites and showed that the kinetic process of potassium reaction in composites can be divided into four stages, and the pores with smaller average diameter distribution are more sensitive to changes in the reaction process. This work paves a new way to study the deposition kinetics of potassium in porous materials, which facilitates the design of porous structures and realizes the development of alkali metal ion-anode materials with high energies.

Enhancing photocatalytic efficiency with Mn-doped ZnO composite carbon nanofibers for organic dye degradation

<abstract> <p>In this study, Mn-doped ZnO composite carbon nanofibers (Mn-ZnO/CNFs) were prepared via a simple blending and electrospinning (ES) method, followed by a thermal treatment. These fibers were used to investigate the photocatalytic degradation of an organic dye under UV and visible light irradiation. The results showed that Mn-ZnO/CNFs were successfully prepared under the same conditions used for CNFs preparation conditions, which induced a morphological change from a smooth to a rough surface compared to the CNFs. Energy dispersive X-ray (EDX), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) analyses confirmed the formation of Mn-doped ZnO on the CNFs' surface. Furthermore, the addition of the catalyst significantly increased in the specific surface area, and a N<sub>2</sub> adsorption-desorption isotherm analysis revealed that all samples had mesoporous characteristics with a type IV isotherm index. The photocatalytic activity of the Mn-ZnO/CNFs carbonized at 650 ℃ using methylene blue (MB) dye as a model pollutant was investigated. All prepared samples effectively removed the MB with a degradation rate of 70-90%. The kinetic reaction rate was described using the simplified Langmuir-Hinshelwood equation. Overall, the CNFs and composites nanofibers developed through moderate thermal treatment processes possessed a high specific surface area and oxygen vacancy, enabling their potential use as adsorbents and as a catalyst support for reactions at room-to-elevated temperatures, as well as photocatalysts for the removal of organic contaminants.</p> </abstract>

Highly flexible multilayer MXene hollow carbon nanofibers confined with Fe3C particles for high-performance lithium-ion batteries

Designing electrode structures with excellent mechanical properties, fast electrochemical kinetics and stability is important for the development of flexible wearable electrodes. In this paper, a hollow carbon nanofiber composite of Ti3C2Tx MXene and Fe3C nanoparticles is designed. The synergistic effect of Ti3C2Tx MXene and Fe3C nanoparticles forms a strong conductive channel with the hollow channel to form a dual conductive channel, which plays an important role in the preparation of high-performance lithium-ion batteries. Benefiting from the advantages of the above structure, the Fe3C@MXene/hollow multichannel carbon fibers (Fe3C@MXene/HMCFs) electrodes at a current density of 0.2 A/g achieve an initial capacity of 1294 mA h g−1 and a high reversible capacity of 831 mA h g−1 after 200 turns of charge/discharge cycles.

Effect of B2O3 on the structure, morphology, and electrochemical properties of hierarchical multilayer carbon nanofiber/MnO2/carbon nanofiber composites

One major challenge in capacitor development is achieving high capacitance and large energy density with rapid charge and discharge rates of minutes to seconds. This paper reports boron-containing trilayer structured MnO2/carbon nanofiber composites(PPMnB) as promising supercapacitor electrodes with high electrochemical properties under rapid charge and discharge conditions. Multilayer carbon nanofiber(CNF) composites are designed to maximize the advantages of CNF, MnO2, and boron functional groups when applying functionalized porous CNF containing transition metal composites to supercapacitor electrodes. The PPMnB electrode exhibits a high specific capacitance (215 Fg−1 at 1 mAcm−2), good rate capability (83 % capacity retention at 20 mAcm−2), high energy density (23.5 Whkg−1 at 400 Wkg−1), and good cycling stability (only 6.0 % loss after 10,000 cycles at 1 mAcm−2). In addition, the asymmetric capacitor of the PPMnB(25) and PPB(0) used as the positive and negative electrode shows excellent electrochemical performance, including an excellent energy density of 46.3 Whkg−1 at a maximum voltage of 1.4 V. High electrochemical performance is achieved through the combined effects of the hierarchical porosity of CNF, high electrochemical activity of MnO2, and increased electrical conductivity by boron functional groups in each layer.

Electrospun Carbon/MXenes Nanofiber Composites for Electrochemical Capacitors

Herein, carbon nanofiber composites derived from polyacrylonitrile/MXene (PAN) using electrospinning technique are proposed as electrode for supercapacitors. Carbon/MXene composite nanofibers were successfully prepared at different MXene contents of 0, 4, 8, and 12 wt. %. Raman spectra displayed rising IG/ID ratio with increase MXene content. XRD results confirmed the embed MXene merged with carbon amorphous. The thermal stability of composite fibers was decreased with adding MXene. Carbon/MXene at 8 wt. % revealed the highest electrochemical supercapacitor of 155.25 F g-1 at 1.0 A g-1 with 100% capacitance retention after 10,000 cycles. Thus, PANMX8 has great potential for supercapacitor application with long-life cycles and fast-charging ability.

Hexagonal crystalline nanofillers reinforced composite carbon nanofibers with optimized crystal structure and improved mechanical properties

The mechanical properties of carbon nanofibers (CNFs) are always restricted by their disorganized crystal structures. Herein, this paper utilizes two typical hexagonal crystalline flake materials, nanoscale flake graphite (NG) and hexagonal nitride boron (BN), as nanofillers to optimize the crystal domains of CNFs and achieves enhancement in fiber strength, modulus and toughness. For this purpose, in situ polymerization technique is developed for the rapid and uniform mixing of nanofillers with polyacrylonitrile (PAN) precursors of CNFs. The nanofillers are exfoliated in this process and wrapped with PAN to prevent potential agglomeration. The obtained core-shell nanocomposites can be produced into composite CNFs via electrospinning, stabilization and carbonization. Based on the attraction effect, the dispersed nanofillers can organize PAN molecular chains into oriented crystalline fibrils in as-spun nanofibers and accelerate their transformation to more ladder structures in stabilized nanofibers. On this basis, NG is shown to act as the templating and nucleating agent to promote the formation, growth and compact stacking of graphitic planes in CNFs. BN also improves fiber crystallinity, while its limited templating effect leads to looser and finer crystal domains. As a result, NG-doped CNFs have significantly improved strength and modulus, and BN-doped CNFs possess simultaneously enhanced strength and toughness.

Strontium phosphate/functionalized carbon nanofiber composite: A promising electrode material for amperometric detection of flufenamic acid

Anti-inflammatory drug pollution and its potentially disastrous consequences have recently emerged as a major health issue worldwide because of its widespread use in inadequate environments. Among, Flufenamic acid (FFA) is a class of anti-inflammatory drugs widely used for therapeutic treatments, and its over usage causes severe issues in the biological systems. In this work, a particle–like strontium phosphate (Sr2P2O7) was prepared. The efficiency was increased by making a composite with functionalized carbon nanofiber (F-CNF) and used to detect FFA. The prepared individual materials (Sr2P2O7 and F-CNF) and the composite (Sr2P2O7@F-CNF) were confirmed by various spectroscopy techniques. The electrochemical studies of Sr2P2O7@F-CNF were done by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). A sensitive i-t amperometry technique was used for the determination of FFA. The attained results show that Sr2P2O7@F-CNF shows a higher active surface area (A= 0.197 cm2), a wide linear range of 0.001–80.8 µM, a low detection limit of 0.9 nM, and higher selectivity. Finally, the Sr2P2O7@F-CNF was taken to the real-time analysis with the water and urine samples. The result shows an acceptable recovery range of ± 97.50–99.66 % for the water and urine samples.

Bacteria immobilized onto carbon nanofiber as a composite for effective removal of arsenic from wastewater

Drinking arsenic-contaminated water is one of the major fears for the health of mankind due to its being of highly toxic and carcinogenic substance. In this perspective, the present work is aimed to prepare Enterococcus faecalis (E. faecalis) immobilized onto carbon nanofiber (CNF) as novel composite sorbent and evaluate it adsorption ability for removal of arsenic ions As(III) from aquatic medium. The Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM)/Energy Dispersive X-Ray (EDX) analysis results displayed that the modification of CNF particles with E. faecalis makes more sorptive sites and the surface functional groups for binding arsenic ions. The designing of the experiment (DOE) methodology was applied to assess the effects of experimental factors on the sorption yield and their significance levels. The designing of factorials was utilized to estimate responses and statistical correlation among experimental parameters. The response surface plots exhibited that the response was higher at an optimum level of variables used in the extraction of arsenic. The equilibrium data under optimized sorption conditions (temperature 24 °C, contact time 30 min, biosorbent amount 500 mg/L and pH 5) were studied for Langmuir and Freundlich isotherms and the data were well fitted to the Langmuir isotherm with obtained maximum removal capacity of 255.2 mg g−1 for monolayer As(III) sorption onto E. faecalis/CNF composite. The sorption mechanism for kinetic studies followed the pseudo-second order model with obtained correlation coefficient (R2 = 0.998). Based on characterization and surface functionalities the proposed adsorption mechanism, the hydrogen bonding, π–π and electrostatic attractions were efficient for bisorption of As(III) onto E. faecalis /CNF composite.

Synthesis of Free-Standing Tin Phosphide/Phosphate Carbon Composite Nanofibers as Anodes for Lithium-Ion Batteries with Improved Low-Temperature Performance.

Free-standing tin phosphide/phosphate carbon composite nanofiber mats of unique nanostructure have been successfully synthesized by electrospinning and partially reducing the phosphate-containing precursors. An unusual effect of the Sn:P molar ratio in the precursor solution on the structure and physical-electrochemical properties of the material is observed. Physical characterizations, including X-Ray diffraction (XRD), Raman spectroscopy, X-Ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), confirm the formation of tin phosphide/phosphate nanoparticles of P-rich inner Snx P layer and Sn-rich outer layer uniformly distributed within carbon nanofiber matrix when the Sn:P=1:1. The prepared material is tested as an anode material for lithium-ion batteries and it retains 1141 mAh g-1 charge capacity after 300 cycles at a current density of 250mA g-1 with almost 100% Coulombic efficiency at room temperature. Furthermore, it demonstrates six times higher capacity (846 mAh g-1 ) at 0°C compared to a commercial graphite anode and stable cyclability at -20 °C and 50mA g-1 . Post-mortem ex situ XRD and SEM analyses confirm the structural stability of the designed material and the formation of a uniform stable solid electrolyte interphase layer even after 100 cycles at 50mA g- 1 .

Preparation and characterization of bifunctional wolfsbane-like magnetic Fe3O4 nanoparticles-decorated lignin-based carbon nanofibers composites for electromagnetic wave absorption and electrochemical energy storage

Recently, with the pursuit of high-efficiency electromagnetic wave absorption (EMWA) and electrochemical energy storage (EES) materials, multifunctional lignin-based composites have attracted significant interest due to their low cost, vast availability, and sustainability. In this work, lignin-based carbon nanofibers (LCNFs) was first prepared by electrospinning, pre-oxidation and carbonization processes. Then, different content of magnetic Fe3O4 nanoparticles were deposited on the surface of LCNFs via the facile hydrothermal way to produce a series of bifunctional wolfsbane-like LCNFs/Fe3O4 composites. Among them, the synthesized optimal sample (using 12 mmol of FeCl3·6H2O named as LCNFs/Fe3O4–2) displayed excellent EMWA ability. When the minimum reflection loss (RL) value achieved −44.98 dB at 6.01 GHz with an thickness of 1.5 mm, and the effective absorption bandwidth (EAB) was up to 4.19 GHz ranging from 5.10 to 7.21 GHz. For supercapacitor electrode, the highest specific capacitance of LCNFs/Fe3O4–2 reached 538.7 F/g at the current density of 1 A/g, and the capacitance retention remained at 80.3 %. Moreover, an electric double layer capacitor of LCNFs/Fe3O4–2//LCNFs/Fe3O4–2 also showed a remarkable power density of 7755.29 W/kg, outstanding energy density of 36.62 Wh/kg and high cycle stability (96.89 % after 5000 cycles). In short, the construction of this multifunctional lignin-based composites has potential applications in electromagnetic wave (EMW) absorbers and supercapacitor electrodes.

Fe2O3 Nanorod/Bacterial Cellulose Carbon Nanofiber Composites for Enhanced Acetone Sensing

Structures and performances from nature provide ideas for humans to deal with energy and environmental crisis. Inspired from natural structures, bacterial cellulose nanofibers with a fine-meshed network were selected as the raw materials to design acetone gas sensors. Here, Fe2O3 nanorods were successfully introduced on the surface of carbon nanofibers by a feasible hydrothermal catalytic carbonization at 120 °C. Lots of heterojunctions between the bacterial cellulose carbon nanofiber and the Fe2O3 nanorod were constructed, resulting in high gas-sensing properties to acetone vapor. At room temperature, the response of Fe2O3/bacterial cellulose carbon nanofiber composite (BCCF–Fe2O3) to 5 ppm of acetone reached 2060% within 10 s. BCCF–Fe2O3 showed high sensitivity and selectivity, ppb-level detection limit (100.7 ppb), nice long-term stability (30 days), low energy consumption (1.4 μW), and good anti-humidity performance in acetone detection. To our surprise, BCCF–Fe2O3 had realized ultrasensitive exhaled acetone detection within 16 s, proving an effective and inexpensive strategy for diabetic noninvasive diagnosis.

Facile synthesis of nickel-decorated multidimensional carbon nanofibers via oxygen plasma activation for non-enzymatic acetaminophen sensing

Acetaminophen (AMP), the most commonly used drug for pain and fever, has very low side effects. However, due to its widespread use, emissions from manufacturing plants and daily life adversely affect various animals and plants, so it is necessary to precisely monitor the concentration. This research suggests the manufacture of composite carbon nanofibers with carbon nanotubes containing nickel particles (Ni–CNT@CNF), and applying the material as an electrochemical sensor electrode material that is capable of measuring AMP. In detail, an oxygen functional group is introduced into the PVP layer by using an O2 vacuum plasma process in a polymer fiber formed by electrospinning a mixed solution of PAN and a PVP including a nickel precursor. The carbon nanotubes are then induced to grow by the catalytic reaction of nickel and decomposed PVP during the carbonization. The Ni–CNT@CNF-based sensor electrode has a low detection limit (0.5 nM), and a wide detection range of (1 nM–70 μM) for AMP molecules. In addition, comparison of sensitivity with other biologically active metabolites demonstrated the excellent selectivity of the sensor electrode.

Graphene-Wrapped Composites of Si Nanoparticles, Carbon Nanofibers, and Pyrolytic Carbon as Anode Materials for Lithium-Ion Batteries

Silicon (Si) anode materials have received much attention on account of their unparalleled theoretical specific capacity, but they suffer from huge volumetric expansion and particle pulverization, which leads to rapid capacity fading and poor electrical conductivity as well. In this work, a quaternary silicon/carbon (Si/C) composite anode material is proposed which combines the advantages of both graphene and the three-dimensional carbon framework through rational structural design and simple synthesis methods. Nanosilicon/carbon nanofibers/pyrolytic carbon (SCC) composite particles are first synthesized by spray drying and pyrolysis, which are then wrapped by graphene nanosheets through a second spray drying and pyrolysis process to obtain the final product (SGCC). In this composite, a 3D carbon skeleton composed of carbon nanofibers and pyrolytic carbon serves as an electric conductive matrix that supports and stabilizes Si nanoparticles, while graphene nanosheets wrapped on the surface further improve the conductivity and structure stability of the composite particles, and isolate the particles from direct contact with electrolytes. Meanwhile, the rich pores of the composite particles can effectively provide space for the volume expansion of Si during lithiation. As a consequence, the as-prepared SGCC composite shows a high initial Coulomb efficiency of 84.7%, a high reversible capacity of 2150.8 mA h g–1, and a good capacity retention rate of 83.75% after 100 cycles.