New Carbon Materials最新文献

Zeolite-templated carbons (ZTCs) have a unique three-dimensional (3D) ordered microporous structure and an extra-large surface area, and have excellent properties in adsorption and energy storage. Unfortunately, the lack of efficient synthesis strategies and the difficulty of doing this on a large-scale have seriously limited their development. We have developed a large-scale simple production route using a relatively low synthesis temperature and direct acetylene chemical vapor deposition (CVD) using Co ion-exchanged zeolite Y (CoY) as the template. The Co²⁺ confined in the zeolite acts as Lewis acid sites to catalyze the pyrolysis of acetylene through the d-π coordination effect, making carbon deposition occur selectively inside the zeolite at 400 °C rather than on the external surface. By systematically investigating the CVD temperature and time, the optimum conditions of 8 h deposition at 400 °C produces an excellent 3D ordered-microporous structure and outstanding structure parameters (3 000 m² g⁻¹, 1.33 cm³ g⁻¹). Its CO₂ adsorption capacity and selectivity are 2.78 mmol g⁻¹ (25 °C, 100 kPa) and 98, respectively. This simple CVD process allows the synthesis of high-quality ZTCs on a large scale at a low cost.

Phenolic resin was coated on the surface of nano-Si by a microencapsulation technique, and then carbonized under Ar protection to prepare a nano-Si/C composite. The composites were first prepared using 4 different mass ratios (1:2, 1:4, 1:6, 1:8) of phenolic resin to nano-Si. The obtained average thicknesses of amorphous carbon coating were 7, 4.5, 3.7, 2.8 nm, respectively. By comparing the cycling and rate capability, the best electrochemical performance was obtained when this ratio was 1:4, with a 4.5 nm amorphous carbon coating. The electrochemical properties of this material were then comprehensively evaluated, showing excellent electrochemical performance as an anode material for Li-ion batteries. At a current density of 100 mAg⁻¹, the material had a first specific discharge capacity of 2 382 mAhg⁻¹, a first charge specific capacity of 1667 mAhg⁻¹, and an initial coulombic efficiency of 70%. A discharge specific capacity of 835.6 mAhg⁻¹ was retained after 200 cycles with a high coulombic efficiency of 99.2%. In addition, the nano-Si/C composite demonstrated superior rate performance. Under current densities of 100, 200, 500, 1 000 and 2 000 mAg⁻¹, the average specific discharge capacities were 1 716.4, 1 231.6, 911.7, 676.1 and 339.8 mAh g⁻¹, respectively. When the current density returned to 100 mA g⁻¹, the specific capacity returned to 1 326.4 mAh g⁻¹.

This review provides an extensive analysis of the recycling and regeneration of battery-grade graphite obtained from used lithium-ion batteries. The main objectives are to address supply-demand challenges and minimize environmental pollution. The study focuses on the methods involved in obtaining, separating, purifying, and regenerating spent graphite to ensure its suitability for high-quality energy storage. To improve the graphite recovery efficiency and solve the problem of residual contaminants, techniques like heat treatment, solvent dissolution, and ultrasound treatment are explored. Wet and pyrometallurgical purification and regeneration methods are evaluated, considering their environmental impact and energy consumption. Sustainable and cost-effective approaches, including acid-free purification and low-temperature graphitization, are highlighted. Specific requirements for regenerated graphite in lithium-ion batteries and supercapacitors are discussed, emphasizing customized recycling processes involving acid leaching, high-temperature treatment, and surface coating. Valuable information for the development of efficient and sustainable energy storage systems is provided, addressing environmental issues, and how to meet the increasing demand for graphite anodes.

Despite recent interest in the low-temperature carbonization of coal to prepare disordered carbon materials for the anodes of lithium-ion (LIBs) and sodium-ion batteries (SIBs), the carbonization mechanism is still poorly understood. We selected bituminous coal as the raw material and investigated the chemical, microcrystal, and pore structure changes during the carbonization process from coal to the resulting disordered carbon. These structural changes with temperature below 1 000 °C show an increase in both interlayer spacing (3.69–3.82 Å) and defect concentration (1.26–1.90), accompanied by the generation of a large amount of nano-microporous materials. These changes are attributed to the migration of the local carbon layer and the release of small molecules. Furthermore, a decrease in interlayer spacing and defect concentration occurs between1 000 °C and 1 600 °C. In LIBs, samples carbonized at 1 000 °C showed the best electrochemical performance, with a reversible capacity of 384 mAh g⁻¹ at 0.1 C and excellent rate performance, maintaining 170 mAh g⁻¹ at 5 C. In SIBs, samples carbonized at 1 200 °C had a reversible capacity of 270.1 mAh g⁻¹ at 0.1 C and a high initial Coulombic efficiency of 86.8%. This study offers theoretical support for refining the preparation of carbon materials derived from coal.

Developing low-cost, highly-efficient and stable catalysts for the oxygen reduction reaction (ORR) of fuel cells is highly desirable yet challenging. We have developed a Co−N−C ORR catalyst with an intact hollow spherical structure and a large surface area which has been systematically characterized. It was produced by the uniform growth of zeolitic imidazolate frameworks (ZIF s) on the surface of nano-polystyrene (PS) spheres followed by their decomposition. Notably, the as-prepared catalyst Co-NHCP-2 (2 represents a mass ratio of 0.6 between Zn(NO₃)₂·6H₂O and 2-methylimidazole) has a porous structure, a super large specific surface area (1 817.24 m² g⁻¹), high contents of pyridinic-N, pyrrolic-N, and graphitic-N, and a uniform Co distribution. As an efficient electrocatalyst, it shows promise in terms of a high onset potential (E_onset) of 0.96 V, a high half-wave potential (E_1/2) of 0.84 V, and a limited current density of 5.50 mA cm⁻². The catalyst has a nearly 4e pathway for the ORR in an alkaline solution as well as stronger methanol tolerance and higher long-term durability than commercially available Pt/C catalysts. These results show that the obtained material may be a promising electrocatalyst for the ORR.

The surface of carbon fibers (CFs) was modified by a surfactant (ferrocenemethyl)dodecyldimethylammonium bromide (FDDA) to enhance the interfacial ashesion between the CFs and surrounding matrix. Results showed that it could be electrochemically desorbed by a potentiostatic electro-oxidation method. The FDDA adsorption isotherm was attributed to the formation of multi-molecular layers mainly by non-electrostatic interactions. The adsorption and desorption of FDDA on the CFs have little effect on their tensile strength. The effects of FDDA modification on the interfacial properties of CF/epoxy composites were evaluated by a single-filament fragmentation test. Compared with the un-modified CFs, the FDDA-modified ones had significantly improved interfacial adhesion properties in the composites. This method provides a potential approach for preparing recyclable CF/resin composites.

A variety of industrial preparation methods to obtain graphene from graphite have been developed, the most prominent of which are the chemical reduction of graphene oxide and intercalation-exfoliation methods. However, the low-cost, thin-layer, large-scale production of graphene with a radial dimension smaller than 1 μm (SG) remains a great challenge, which has limited the industrial development and application of small-scale graphene in areas such as textile fibers, engine oil additives, and graphene-polymer composites. We have developed a novel way to solve this problem by improved ball milling methods which form molecular-scale grinding aids between the graphite layers. This method can produce uniform, small-size (less than 1 μm) and thin-layer graphene nanosheets at a low cost, while ensuring minimal damage to the internal graphene structure. We also show that using this SG as an additive in lubricating oil not only solves the current dispersion stability of graphene, but also reduces the friction coefficient by more than 27% and wear by more than 38.8%. The SG preparation method reported is simple, low-cost, and has a significant effect in lubricating applications, which is of great commercial value.

The rapid development of flexible supercapacitors has been impeded by the difficulty of preparing flexible electrodes. We report the fabrication of a highly flexible and conductive microporous graphene-based substrate obtained by direct laser writing combined with KOH activation, which we call activated laser-produced graphene (a-LPG), which is then decorated with electrochemically deposited MnO₂ to form a flexible a-LIG/MnO₂ thin-film electrode. This hybrid electrode has a high areal capacitance of 304.61 mF/cm² at a current density of 1 mA/cm² in a 1 mol/L Na₂SO₄ aqueous electrolyte. A flexible asymmetric supercapacitor with a-LIG/MnO₂ as the anode, a-LIG as the cathode and PVA/ H₃PO₄ as a gel electrolyte was assembled, giving an areal energy density of 2.61 μWh/cm² at a power density of 260.28 μW/cm² and an ultra-high areal capacitance of 18.82 mF/cm² at 0.2 mA/cm² with 90.28% capacitance retained after 5 000 cycles. It also has an excellent electrochemical performance even in the bent state. This work provides an easy and scalable method to design high-performance flexible supercapacitor electrodes and may open a new way for their large-scale fabrication.

Severe dendritic growth and volume expansion are easily induced during the cycling process when lithium metal is used as an anode electrode directly. These problems cause the solid electrolyte interface (SEI) layer to break and re-form, which consumes the active lithium metal and electrolyte, thereby reducing the Coulomb efficiency and rapid capacity. Designing a host matrix with rapid mass transfer and enough storage space to promote lithium homogeneous deposition, hence reducing the repeated SEI growth and the formation of dead lithium, is an effective method to address the concerns mentioned above issues. MXenes with two-dimensional layered structures have been regarded as feasible hosts for stabilizing lithium due to their superior electrical conductivity, sizeable interlayer space, abundant lithiophilic surface functional groups, and excellent mechanical properties. In this review, we first summarized the multiple synthesis methods of MXenes, including etching the precursor MAX phase, chemical vapor deposition, UV-induced etching, and mechanochemical et al. Various synthesis methods would induce different surface termination and lamellar structures, affecting lithium metal nucleation and growth behavior. Subsequently, pure MXene, MXene-carbon and MXene-non carbon hybrid compounds applied for lithium metal anode hosts were introduced, focusing on alleviating noticeable volume changes and inhibiting lithium dendrite growth. Finally, some modification strategies and potential research prospects were summarized and prospected.

We report the fabrication of a lithiophilic Ti₃C₂T_x MXene-modified carbon foam (Ti₃C₂T_x-MX@CF) for the production of highly-stable LMBs that regulates Li nucleation behavior and reduces the volume change of a lithium metal anode (LMA). The 3D CF skeleton with a high specific surface area not only reduces the local current density to avoiding concentrated polarization, but also provides enough space to absorb the volume expansion during cycling. The excellent lithiophilicity of Ti₃C₂T_x-MX produced by its abundant functional groups reduces the Li nucleation overpotential, guides uniform Li deposition without the formation of Li dendrites, and maintains a stable SEI on the anode surface. Consequently, a Li infiltrated Ti₃C₂T_x-MX@CF symmetrical cell has an excellent cycling stability for more than 2 400 h with a low overpotential of 9 mV at a current density of 4 mA cm^-2 and has a capacity of 1 mA h cm^-2. Furthermore, a Li- Ti₃C₂T_x-MX@C||NCM111 full cell has a capacity of 129.6 mA h g^-1 even after 330 cycles at 1 C, demonstrating the advantage of this method in constructing stable LMAs.