摘要: 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.
摘要: As the temperature of electronic devices continues to rise, the quest for high-efficiency heat dissipation has emerged as a critical concern, particularly when it comes to ensuring device performance and longevity. A high thermal conductivity is usually dependent on the ability of fillers to provide thermal conduction channels within composites. In recent years, the development of three-dimensional (3D) interconnected structures using high thermal conductivity fillers in composites has emerged as a promising approach. Compared to the traditional isotropic distribution and directional arrangements, 3D interconnected filler structures improve the thermal conductivity. We review research progress on metal matrix composites with a 3D interconnected carbon filler that have a high thermal conductivity. The thermal conductivity mechanisms and models of composites are elaborated, and important factors relevant to improving the thermal conductivity are considered. Ways of constructing 3D interconnected carbon networks and their effects on the thermal conductivity of their composites should serve as a reference for the advancement of high-performance metal matrix thermal conductivity composites.
摘要: Single-wall carbon nanotubes (SWCNTs) have been used to fabricate hydrogen gas (H2) detectors for several decades. It has been proven that they barely interact with H2 so that numerous modifications are used to assist this function. Additives include metals, metal oxides, polymers etc. Previous research suggests that the presence of functional groups on the SWCNTs may improve the response by several orders of magnitude. Recently, many different novel structures have been exploited, and structural parameters of the SWCNTs, such as diameter and chirality, also influence the performance of the detectors. Modifications of the SWCNTs are classified and other factors that influence the performance are also discussed, with the aim of accelerating the manufacture of detectors with a high responsivity and low limit of detection.
摘要: Capacitive deionization (CDI) is a potential cost-efficient desalination technology. Its performance is intrinsically limited by the structure and properties of the electrode materials. Biomass materials have become a research hotspot for CDI electrode materials because of their abundance, low cost, and unique structure. The preparation, desalination performance, and regeneration status of biochar electrodes are summarized and clarified. Their preparation and use in CDI in recent years are presented and compared, and the effects of biochar electrode materials and CDI operating parameters on the desalination performance are emphasized. It is found that the salt adsorption capacity is positively correlated with the percent mesoporous material they contain. The selective adsorption of ions mainly depends on ion properties like ionic radius and charge as well as voltage, charging time and feed water characteristics. The current status and methods of electrode regeneration are discussed and future developments are suggested.
摘要: 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.
摘要: Vertically aligned carbon nanotube (VACNT) arrays with good mechanical properties and high thermal conductivity can be used as effective thermal interface materials in thermal management. In order to take advantage of the high thermal conductivity along the axis of nanotubes, the quality and height of the arrays need to be optimized. However, the immense synthesis parameter space for VACNT arrays and the interdependence of structural features make it challenging to improve both their height and quality. We have developed a literature mining approach combined with machine learning and high-throughput design to efficiently optimize the height and quality of the arrays. To reveal the underlying relationship between VACNT structures and their key growth parameters, we used random forest regression (RFR) and SHapley Additive exPlanation (SHAP) methods to model a set of published sample data (864 samples). High-throughput experiments were designed to change 4 key parameters: growth temperature, growth time, catalyst composition, and concentration of the carbon source. It was found that a screened Fe/Gd/Al2O3 catalyst was able to grow VACNT arrays with millimeter-scale height and improved quality. Our results demonstrate that this approach can effectively deal with multi-parameter processes such as nanotube growth and improve control over their structures.
摘要: Two-dimensional (2D) carbon materials have attracted enormous attention, but the complicated synthesis methods, inhomogeneous structure and uncontrollable properties still limit their use. Here we report a universal protocol for fabricating a series of heteroatom-doped 2D porous polymers, including pyrrole and indole as nitrogen-dopant sources, and 3,4-ethoxylene dioxy thiophene as a sulfur-dopant source by a simple chemical crosslinking reaction. This bottom-up strategy allows for the large-scale synthesis of functionalized ultrathin carbon nanosheets with a high heteroatom doping content and abundant porosity. Consequently, the obtained N-doped carbon-rich nanosheets (NCNs) sample has a specific capacity of 573.4 mAh g−1 at 5 A g−1 as an anode for lithium-ion capacitors (LICs), and the optimized sample has a specific capacitance of 100.0 F g−1 at 5 A g−1 when used as a cathode for a LIC. A dual-carbon LIC device was also developed that had an energy density of 168.4 Wh kg−1 at 400 W kg−1, while maintaining outstanding cycling stability with a retention rate of 86.3% after 10 000 cycles. This approach has the potential to establish a way for the precise synthesis of substantial amounts of 2D functionalized carbon nanosheets with the desired structure and properties.
摘要: 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.
摘要: Recently, solar-driven interfacial water evaporation (SDIWE) has attracted worldwide attention owing to its potential use in seawater desalination and wastewater purification. Nevertheless, how to effectively use the inevitable conduction heat loss and eliminate organic pollutants are still challenging. We report the SDIWE- assisted adsorption of organic pollutants by using the conduction heat loss to improve the total energy efficiency of the SDIWE system. Porous carbon (PC) and activated PC were prepared by a simple recrystallizing salt template-assisted carbonization and KOH activation method. After activation, the activated PC sample with a PC:KOH mass ratio of 1:4 (PC-A4) has a hierarchical porous structure, a better absorption capacity in the spectral region of 200-2500 nm, a high specific surface area of 1867.71 m2 g−1 and a large pore volume of 1.04 cm3 g−1. Based on this, PC-A4 has a high evaporation rate and energy efficiency, which can be further increased by regulating the mass of the water body. Subsequently, the conduction heat generated by the SDIWE system was used for SDIWE-assisted adsorption. Notably, the maximum amount of rhodamine B adsorbed by PC-A4 is 1610 mg g−1 at a conduction temperature of 309 K, which is higher than that of the same sample at 298 K. Consequently, this work offers a promising approach for effectively using the conduction heat loss of the SDIWE system and developing it for water purification.
摘要: 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 between 1 000 °C and 1 600 °C. In LIBs, samples carbonized at 1000 °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.
摘要: 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.
摘要: 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 1 667 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.
摘要: 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 (1817.24 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 (Eonset) of 0.96 V, a high half-wave potential (E1/2) 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.
摘要: 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.