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Electrochemical method for impurity removal of graphite anode in spent ternary lithium-ion batteries
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doi: 10.1016/S1872-5805(24)60843-7
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2024, 39(2): 173-200.
doi: 10.1016/S1872-5805(24)60830-9
Abstract:
Graphdiyne (GDY), a new two-dimensional (2D) carbon molecule, is expected to have applications in the removal of contaminants from aqueous media. It has superior conjugation, unusual and varied electronic properties, and exceptional chemical and thermal stability because of its framework of sp and sp2 hybridized carbon bonds that are combined to produce benzene rings and diacetylenic bonds in a two-dimensional symmetrical network. Its molecular chemistry is the result of it having carbon-carbon triple bonds, with a regular distribution of triangular pores in its structure, which provide reaction sites and various reaction pathways. GDY is an adsorbent with an excellent efficiency for the removal of oil, organic pollutants, dyes, and metals from contaminated water, but there is limited evidence of it being used as an adsorbent in the literature. This review discusses its synthesis and its use as an adsorbent together with its prospects for pollutant removal.
Graphdiyne (GDY), a new two-dimensional (2D) carbon molecule, is expected to have applications in the removal of contaminants from aqueous media. It has superior conjugation, unusual and varied electronic properties, and exceptional chemical and thermal stability because of its framework of sp and sp2 hybridized carbon bonds that are combined to produce benzene rings and diacetylenic bonds in a two-dimensional symmetrical network. Its molecular chemistry is the result of it having carbon-carbon triple bonds, with a regular distribution of triangular pores in its structure, which provide reaction sites and various reaction pathways. GDY is an adsorbent with an excellent efficiency for the removal of oil, organic pollutants, dyes, and metals from contaminated water, but there is limited evidence of it being used as an adsorbent in the literature. This review discusses its synthesis and its use as an adsorbent together with its prospects for pollutant removal.
2024, 39(2): 201-222.
doi: 10.1016/S1872-5805(24)60838-3
Abstract:
Lithium-sulfur (Li-S) batteries are among the most promising next-generation electrochemical energy-storage systems due to their exceptional theoretical specific capacity, inexpensive production cost and environmental friendliness. However, the poor conductivity of S and Li2S, severe lithium polysulfide (LiPS) shuttling and the sluggish redox kinetics of the phase transformation greatly hinder their commercialization. Carbonaceous materials could be potentially useful in Li-S batteries to tackle these problems with their high specific surface area to host LiPSs and sulfur and excellent electrical conductivity to increase electron transfer rate. However, non-polar carbon materials are unable to interact closely with the highly polar polysulfides, resulting in a low sulfur utilization and a serious shuttle effect. Because of their advantages of strong polarity and a large number of adsorption sites, integrating transition metal oxides (TMOs) with carbon-based materials (CMs) increases the chemical adsorption of LiPSs and electrochemical reaction activity for LiPSs. The working principles and main challenges of Li-S batteries are discussed followed by a review of recent research on the ex-situ and in-situ synthesis of TMO/CM composites. The formation of TMO/CMs with the dimensionalities of CMs from 1D to 3D are then reviewed together with ways of changing their structure, including heterostructure design, vacancy engineering and facet manipulation. Finally, the outlook for using TMO/CMs in Li-S batteries is considered.
Lithium-sulfur (Li-S) batteries are among the most promising next-generation electrochemical energy-storage systems due to their exceptional theoretical specific capacity, inexpensive production cost and environmental friendliness. However, the poor conductivity of S and Li2S, severe lithium polysulfide (LiPS) shuttling and the sluggish redox kinetics of the phase transformation greatly hinder their commercialization. Carbonaceous materials could be potentially useful in Li-S batteries to tackle these problems with their high specific surface area to host LiPSs and sulfur and excellent electrical conductivity to increase electron transfer rate. However, non-polar carbon materials are unable to interact closely with the highly polar polysulfides, resulting in a low sulfur utilization and a serious shuttle effect. Because of their advantages of strong polarity and a large number of adsorption sites, integrating transition metal oxides (TMOs) with carbon-based materials (CMs) increases the chemical adsorption of LiPSs and electrochemical reaction activity for LiPSs. The working principles and main challenges of Li-S batteries are discussed followed by a review of recent research on the ex-situ and in-situ synthesis of TMO/CM composites. The formation of TMO/CMs with the dimensionalities of CMs from 1D to 3D are then reviewed together with ways of changing their structure, including heterostructure design, vacancy engineering and facet manipulation. Finally, the outlook for using TMO/CMs in Li-S batteries is considered.
2024, 39(2): 223-239.
doi: 10.1016/S1872-5805(24)60840-1
Abstract:
The development of communication technology has had great benefits but the detrimental effects of electromagnetic radiation have also become important. There has therefore been growing research on electromagnetic shielding materials that have a wide shielding range, high absorption efficiency and stability. Graphene, a lightweight material with an exceptional electrical conductivity and a large specific surface area, has remarkable potential in this application. We first elucidate the fundamental principles of electromagnetic shielding and the structural characteristics of graphene-based materials while highlighting their unique electromagnetic shielding properties. We also provide an overview of common strategies for changing graphene-based materials including structural modification, heteroatom doping, and their incorporation in composite materials to improve this property. Structural modification can increase the losses of electromagnetic waves by absorption and multiple reflection, and heteroatom doping and incorporation in composite materials can increase the losses by interface polarization and magnetic effects. We also summarize various ways of modifying the materials so that they are lightweight and have a high shielding bandwidth.
2024, 39(2): 240-253.
doi: 10.1016/S1872-5805(24)60827-9
Abstract:
In recent years, photothermal-driven desalination has been regarded as one of the most promising methods to solve the global crisis of freshwater scarcity. The solar generation of water vapor (SGWV) is a key process in seawater desalination which uses simple equipment and has a high cost-benefit. Among alternative photothermal conversion materials for a SGWV system, three-dimensional (3D) monolithic carbon-based materials have many advantages, including low cost, good structure control, and high light-harvesting efficiency which gives a high evaporation rate. 3D monolithic carbon-based materials with a high photothermal conversion efficiency are reviewed together with their use in interface SGWV. The working mechanism of SGWV and the classification of SGWV materials are first considered, followed by detailed consideration of 3D monolithic carbon materials, including their design, preparation and working mechanism in SGWV. Finally, both the advantages and disadvantages of 3D monolithic carbon materials with a high photothermal conversion efficiency are examined.
2024, 39(2): 254-270.
doi: 10.1016/S1872-5805(24)60846-2
Abstract:
Electrocatalytic oxygen reduction by a 2e− pathway enables the instantaneous synthesis of H2O2, a process that is far superior to the conventional anthraquinone process. In recent years, the electrocatalytic synthesis of H2O2 using carbon electrodes has attracted more and more attention because of its excellent catalytic performance and superior stability. The relationship between material modification, wettability and the rate of H2O2 synthesis and service life is considered together with the three-phase interface. The structure of the carbon electrodes and the principles of electrocatalytic H2O2 synthesis are first introduced, and four major catalysts are reviewed, namely, monolithic carbon materials, metal-free catalysts, noble metal catalysts and non-precious metal catalysts. The effects of the metal anode and the electrolyte on the three-phase interface are described. The relationship between carbon electrode wettability and the three-phase interface is described, pointing out that modification focusing on improving the selectivity of the 2e− pathway can also impact electrode wettability. In addition, the relationship between the design of the components in the electrochemical system and their effect on the efficiency of H2O2 synthesis is discussed for carbon electrodes. Finally, we present our analysis of the current problems in the electrocatalytic synthesis of H2O2 for carbon electrodes and future research directions.
Electrocatalytic oxygen reduction by a 2e− pathway enables the instantaneous synthesis of H2O2, a process that is far superior to the conventional anthraquinone process. In recent years, the electrocatalytic synthesis of H2O2 using carbon electrodes has attracted more and more attention because of its excellent catalytic performance and superior stability. The relationship between material modification, wettability and the rate of H2O2 synthesis and service life is considered together with the three-phase interface. The structure of the carbon electrodes and the principles of electrocatalytic H2O2 synthesis are first introduced, and four major catalysts are reviewed, namely, monolithic carbon materials, metal-free catalysts, noble metal catalysts and non-precious metal catalysts. The effects of the metal anode and the electrolyte on the three-phase interface are described. The relationship between carbon electrode wettability and the three-phase interface is described, pointing out that modification focusing on improving the selectivity of the 2e− pathway can also impact electrode wettability. In addition, the relationship between the design of the components in the electrochemical system and their effect on the efficiency of H2O2 synthesis is discussed for carbon electrodes. Finally, we present our analysis of the current problems in the electrocatalytic synthesis of H2O2 for carbon electrodes and future research directions.
2024, 39(2): 271-282.
doi: 10.1016/S1872-5805(24)60835-8
Abstract:
Graphene and its derivatives are often preferentially oriented horizontally during processing because of their two-dimensional (2D) layer structure. As a result, thermal interface materials (TIMs) composed of a polymer matrix and graphene-derived fillers often have a high in-plane (IP) thermal conductivity (K), however, the low through-plane (TP) K makes them unsuitable for practical use. We report the development of high-quality polyimide/graphite nanosheets (PG) perpendicular to the plane using a directional freezing technique that increase the TP K of polymer-based composites. Graphene-derived nanosheets (GNs) were obtained by the crushing of scraps of highly thermally conductive graphene films. A water-soluble polyamic acid salt solution was used to disperse the hydrophobic GNs filler to achieve directional freezing. The polyimide, which facilitated the directional alignment of the GNs, was then graphitized. The introduction of the GNs increases the order and density of the PG, thus improving the strength and heat transfer performance of its polydimethylsiloxane (PDMS) composite. The obtained PG/PDMS composite (21.1% PG, mass fraction) has an impressive TP K of14.56 W·m−1·K−1, 81 times that of pure PDMS. This simple polyimide-assisted 2D hydrophobic fillers alignment method provides ideas for the widespread fabrication of anisotropic TIMs and enables the reuse of scraps of graphene films.
Graphene and its derivatives are often preferentially oriented horizontally during processing because of their two-dimensional (2D) layer structure. As a result, thermal interface materials (TIMs) composed of a polymer matrix and graphene-derived fillers often have a high in-plane (IP) thermal conductivity (K), however, the low through-plane (TP) K makes them unsuitable for practical use. We report the development of high-quality polyimide/graphite nanosheets (PG) perpendicular to the plane using a directional freezing technique that increase the TP K of polymer-based composites. Graphene-derived nanosheets (GNs) were obtained by the crushing of scraps of highly thermally conductive graphene films. A water-soluble polyamic acid salt solution was used to disperse the hydrophobic GNs filler to achieve directional freezing. The polyimide, which facilitated the directional alignment of the GNs, was then graphitized. The introduction of the GNs increases the order and density of the PG, thus improving the strength and heat transfer performance of its polydimethylsiloxane (PDMS) composite. The obtained PG/PDMS composite (21.1% PG, mass fraction) has an impressive TP K of14.56 W·m−1·K−1, 81 times that of pure PDMS. This simple polyimide-assisted 2D hydrophobic fillers alignment method provides ideas for the widespread fabrication of anisotropic TIMs and enables the reuse of scraps of graphene films.
2024, 39(2): 283-296.
doi: 10.1016/S1872-5805(24)60823-1
Abstract:
Micro-supercapacitors (MSCs) are of interest because of their high power density and excellent cycling performance, offering a broad array of potential applications. However, preparing electrodes for the MSCs with an extremely high areal capacitance and energy density remains a challenge. We constructed MSC electrodes with an ultra-high area capacitance and a high energy density, using reduced graphene oxide aerogel (GA) and MoS2 as the active materials, combined with 3D printing and surface modification. Using 3D printing, we obtained electrodes with a stable macrostructure and a GA-crosslinked micropore structure. We also used a solution method to load the surface of the printed electrode with molybdenum disulfide nanosheets, further improving the electrochemical performance. The surface capacitance of the electrode reached 3.99 F cm−2, the power density was 194 W cm−2, and the energy density was 1997 mWh cm−2, confirming its excellent electrochemical performance and cycling stability. This work provides a simple and efficient method for preparing MSC electrodes with a high areal capacitance and energy density, making them ideal for portable electronic devices.
Micro-supercapacitors (MSCs) are of interest because of their high power density and excellent cycling performance, offering a broad array of potential applications. However, preparing electrodes for the MSCs with an extremely high areal capacitance and energy density remains a challenge. We constructed MSC electrodes with an ultra-high area capacitance and a high energy density, using reduced graphene oxide aerogel (GA) and MoS2 as the active materials, combined with 3D printing and surface modification. Using 3D printing, we obtained electrodes with a stable macrostructure and a GA-crosslinked micropore structure. We also used a solution method to load the surface of the printed electrode with molybdenum disulfide nanosheets, further improving the electrochemical performance. The surface capacitance of the electrode reached 3.99 F cm−2, the power density was 194 W cm−2, and the energy density was 1997 mWh cm−2, confirming its excellent electrochemical performance and cycling stability. This work provides a simple and efficient method for preparing MSC electrodes with a high areal capacitance and energy density, making them ideal for portable electronic devices.
2024, 39(2): 297-307.
doi: 10.1016/S1872-5805(24)60842-5
Abstract:
Hard carbon, known for its abundant resources, stable structure and high safety, has emerged as the most popular anode material for sodium-ion batteries (SIBs). Among various sources, coal-derived hard carbon has attracted extensive attention. In this work, N and S co-doped coal-based carbon material (NSPC1200) was synthesized through a combination of two-step carbonization process and heteroatom doping using long-flame coal as a carbon source, thiourea as a nitrogen and sulfur source, and NaCl as a template. The two-step carbonization process played a crucial role in adjusting the structure of carbon microcrystals and expanding the interlayer spacing. The N and S co-doping regulated the electronic structure of carbon materials, endowing more active sites. Additionally, the introduction of NaCl as a template contributed to the construction of pore structure, which facilitates better contact between electrodes and electrolytes, enabling more efficient transport of Na+ and electrons. Under the synergistic effect, NSPC1200 exhibited exceptional sodium storage capacity, reaching 314.2 mAh g−1 at 20 mA g−1. Furthermore, NSPC1200 demonstrated commendable cycling stability, maintaining a capacity of 224.4 mAh g−1 even after 200 cycles. This work successfully achieves the strategic tuning of the microstructure of coal-based carbon materials, ultimately obtaining hard carbon anode with excellent electrochemical performance.
Hard carbon, known for its abundant resources, stable structure and high safety, has emerged as the most popular anode material for sodium-ion batteries (SIBs). Among various sources, coal-derived hard carbon has attracted extensive attention. In this work, N and S co-doped coal-based carbon material (NSPC1200) was synthesized through a combination of two-step carbonization process and heteroatom doping using long-flame coal as a carbon source, thiourea as a nitrogen and sulfur source, and NaCl as a template. The two-step carbonization process played a crucial role in adjusting the structure of carbon microcrystals and expanding the interlayer spacing. The N and S co-doping regulated the electronic structure of carbon materials, endowing more active sites. Additionally, the introduction of NaCl as a template contributed to the construction of pore structure, which facilitates better contact between electrodes and electrolytes, enabling more efficient transport of Na+ and electrons. Under the synergistic effect, NSPC1200 exhibited exceptional sodium storage capacity, reaching 314.2 mAh g−1 at 20 mA g−1. Furthermore, NSPC1200 demonstrated commendable cycling stability, maintaining a capacity of 224.4 mAh g−1 even after 200 cycles. This work successfully achieves the strategic tuning of the microstructure of coal-based carbon materials, ultimately obtaining hard carbon anode with excellent electrochemical performance.
2024, 39(2): 308-320.
doi: 10.1016/S1872-5805(24)60845-0
Abstract:
It is imperative to design suitable anode materials for both lithium-ion (LIBs) and sodium-ion batteries (SIBs) with a high-rate performance and ultralong cycling life. We fabricated a MoO2/MoS2 heterostructure that was then homogeneously distributed in N,S-doped carbon nanofibers (MoO2/MoS2@NSC) by electrospinning and sulfurization. The one-dimensional carbon fiber skeleton serves as a conductive frame to decrease the diffusion pathway of Li+/Na+, while the N/S doping creates abundant active sites and significantly improves the ion diffusion kinetics. Moreover, the deposition of MoS2 nanosheets on the MoO2 bulk phase produces an interface that enables fast Li+/Na+ transport, which is crucial for achieving high efficiency energy storage. Consequently, as the anode for LIBs, MoO2/MoS2@NSC gives an excellent cycling stability of 640 mAh g−1 for 2000 cycles under 5.0 A g−1 with an ultralow average capacity drop of 0.002% per cycle and an exceptional rate capability of 614 mAh g−1 at 10.0 A g−1. In SIBs, it also produces a significantly better electrochemical performance (reversible capacity of 242 mAh g−1 under 2.0 A g−1 for 2000 cycles and 261 mAh g−1 under 5.0 A g−1). This work shows how introducing a novel interface in the anode can produce rapid Li+/Na+ storage kinetics and a long cycling performance.
It is imperative to design suitable anode materials for both lithium-ion (LIBs) and sodium-ion batteries (SIBs) with a high-rate performance and ultralong cycling life. We fabricated a MoO2/MoS2 heterostructure that was then homogeneously distributed in N,S-doped carbon nanofibers (MoO2/MoS2@NSC) by electrospinning and sulfurization. The one-dimensional carbon fiber skeleton serves as a conductive frame to decrease the diffusion pathway of Li+/Na+, while the N/S doping creates abundant active sites and significantly improves the ion diffusion kinetics. Moreover, the deposition of MoS2 nanosheets on the MoO2 bulk phase produces an interface that enables fast Li+/Na+ transport, which is crucial for achieving high efficiency energy storage. Consequently, as the anode for LIBs, MoO2/MoS2@NSC gives an excellent cycling stability of 640 mAh g−1 for 2000 cycles under 5.0 A g−1 with an ultralow average capacity drop of 0.002% per cycle and an exceptional rate capability of 614 mAh g−1 at 10.0 A g−1. In SIBs, it also produces a significantly better electrochemical performance (reversible capacity of 242 mAh g−1 under 2.0 A g−1 for 2000 cycles and 261 mAh g−1 under 5.0 A g−1). This work shows how introducing a novel interface in the anode can produce rapid Li+/Na+ storage kinetics and a long cycling performance.
2024, 39(2): 321-333.
doi: 10.1016/S1872-5805(24)60844-9
Abstract:
Efficient electrocatalysts with a low cost, high activity and good durability play a crucial role in the use of direct formic acid fuel cells. Pd nanoparticles supported on N-doped hollow carbon nanospheres (NHCNs) embedded in an assembly of N-doped graphene (NG) with a three-dimensional (3D) porous structure by a simple and economical method were investigated as direct formic acid fuel cell catalysts. Because of the unique porous configuration of interconnected layers doped with nitrogen atoms, the Pd/NHCN@NG catalyst with Pd nanoparticles has a large catalytic active surface area, superior electrocatalytic activity, a high steady-state current density, and a strong resistance to CO poisoning, far surpassing those of conventional Pd/C, Pd/NG, and Pd/NHCN catalysts for formic acid electrooxidation. When the HCN/GO mass ratio was 1∶1, the Pd/NHCN@NG catalyst had an outstanding performance in the catalytic oxidation of formic acid, with an activity 4.21 times that of Pd/C. This work indicates a way to produce superior carbon-based support materials for electrocatalysts, which will be beneficial for the development of fuel cells.
Efficient electrocatalysts with a low cost, high activity and good durability play a crucial role in the use of direct formic acid fuel cells. Pd nanoparticles supported on N-doped hollow carbon nanospheres (NHCNs) embedded in an assembly of N-doped graphene (NG) with a three-dimensional (3D) porous structure by a simple and economical method were investigated as direct formic acid fuel cell catalysts. Because of the unique porous configuration of interconnected layers doped with nitrogen atoms, the Pd/NHCN@NG catalyst with Pd nanoparticles has a large catalytic active surface area, superior electrocatalytic activity, a high steady-state current density, and a strong resistance to CO poisoning, far surpassing those of conventional Pd/C, Pd/NG, and Pd/NHCN catalysts for formic acid electrooxidation. When the HCN/GO mass ratio was 1∶1, the Pd/NHCN@NG catalyst had an outstanding performance in the catalytic oxidation of formic acid, with an activity 4.21 times that of Pd/C. This work indicates a way to produce superior carbon-based support materials for electrocatalysts, which will be beneficial for the development of fuel cells.
2024, 39(2): 334-344.
doi: 10.1016/S1872-5805(24)60826-7
Abstract:
Mesophase-pitch-based carbon fibers (MPCFs) were prepared using industrial equipment with a constant extrusion rate of pitch while controlling the spinning temperature. The influence of spinning temperature on their microstructures, mechanical properties and thermal conductivities was investigated. SEM images of the fractured surface of MPCFs show that the graphite layers have a radiating structure at all spinning temperatures, but change from the fine-and-folded to the large-and-flat morphology when increasing the spinning temperature from 309 to 320 oC . At the same time the thermal conductivity and tensile strength of the MPCFs respectively increase from 704 W·m−1·K−1 and 2.16 GPa at 309 oC to 1 078 W·m−1·K−1 and 3.23 GPa at 320 oC. The lower viscosity and the weaker die-swell effect of mesophase pitch at the outlets of the spinnerets at the higher spinning temperature contribute to the improved orientation of mesophase pitch molecules in the pitch fibers, which improves the crystallite size and orientation of the MPCFs.
Mesophase-pitch-based carbon fibers (MPCFs) were prepared using industrial equipment with a constant extrusion rate of pitch while controlling the spinning temperature. The influence of spinning temperature on their microstructures, mechanical properties and thermal conductivities was investigated. SEM images of the fractured surface of MPCFs show that the graphite layers have a radiating structure at all spinning temperatures, but change from the fine-and-folded to the large-and-flat morphology when increasing the spinning temperature from 309 to 320 oC . At the same time the thermal conductivity and tensile strength of the MPCFs respectively increase from 704 W·m−1·K−1 and 2.16 GPa at 309 oC to 1 078 W·m−1·K−1 and 3.23 GPa at 320 oC. The lower viscosity and the weaker die-swell effect of mesophase pitch at the outlets of the spinnerets at the higher spinning temperature contribute to the improved orientation of mesophase pitch molecules in the pitch fibers, which improves the crystallite size and orientation of the MPCFs.
2024, 39(2): 345-353.
doi: 10.1016/S1872-5805(24)60825-5
Abstract:
The lithium−sulfur (Li-S) battery is a promising energy storage system because of its high energy density and low cost. However, the shuttling of lithium polysulfides (LiPSs) and low conductivity of the S cathode are barriers to its practical application. Fe2O3 nanorods were grown on a carbon cloth (Fe2O3/CC) by a solvothermal reaction and calcination to obtain a cathode for the battery. The mesoporous structure of the Fe2O3 and the CC conducting network facilitates lithium-ion and electron transport. Meanwhile, the nanorod arrangement results in the exposure of more Fe2O3 active sites, which improves the adsorption and rapid conversion of LiPSs. As a result, a Li–S cell using a Fe2O3/CC cathode has a high capacity of 1250 mAh g−1 at 0.1 C with an excellent life of over 100 cycles with a capacity retention of 67%. It also has a 70% capacity retention after 1000 cycles at 0.2 C. The excellent electrochemical performance of the Fe2O3/CC cathode indicates its potential applications in Li-S batteries.
2024, 39(2): 354-366.
doi: 10.1016/S1872-5805(22)60597-3
Abstract:
The oxidation reaction mechanism and its kinetics for ethylene tar were investigated in order to obtain a suitable anode material for Li-ion batteries. The oxidation of ethylene tar was divided into 3 stages (350–550, 550–700 and 700–900 K) according to the thermogravimetric curve. To reveal the oxidation reaction mechanism, the components of the gases evolved at different stages were analyzed by mass spectrometry and infrared technology. Based on these results the reaction was divided into 4 stages (323–400, 400–605, 605–750 and 750–860 K) to perform simulation calculations of the kinetics. Using the iso-conversion method (Coats-Redfern) to analyze the linear regression rates (R2) between 17 common reaction kinetics models and experimental data, an optimum reaction kinetics model for expressing the oxidation of ethylene tar was determined and the results were as follows. (1) During oxidation, the side chains of aromatic compounds first react with oxygen to form alcohols and aldehydes, leaving peroxy-radicals on aromatic rings. Subsequently, the aromatic compounds with peroxy-radicals undergo polymerization/condensation reactions to form larger molecules. (2) A fourth-order reaction model was used to describe the first 3 stages in the oxidation process, and the activation energies are 47.33, 18.69 and 9.00 kJ·mol−1 at 323–400, 400–605, 605–750 K, respectively. A three-dimensional diffusion model was applied to the fourth stage of the oxidation process, and the activation energy is 88.37 kJ·mol−1 at 750–860 K. A high softening point pitch was also produced for use as a coating of the graphite anode, and after it had been applied the capacity retention after 300 cycles increased from 51.54% to 79.07%.
The oxidation reaction mechanism and its kinetics for ethylene tar were investigated in order to obtain a suitable anode material for Li-ion batteries. The oxidation of ethylene tar was divided into 3 stages (350–550, 550–700 and 700–900 K) according to the thermogravimetric curve. To reveal the oxidation reaction mechanism, the components of the gases evolved at different stages were analyzed by mass spectrometry and infrared technology. Based on these results the reaction was divided into 4 stages (323–400, 400–605, 605–750 and 750–860 K) to perform simulation calculations of the kinetics. Using the iso-conversion method (Coats-Redfern) to analyze the linear regression rates (R2) between 17 common reaction kinetics models and experimental data, an optimum reaction kinetics model for expressing the oxidation of ethylene tar was determined and the results were as follows. (1) During oxidation, the side chains of aromatic compounds first react with oxygen to form alcohols and aldehydes, leaving peroxy-radicals on aromatic rings. Subsequently, the aromatic compounds with peroxy-radicals undergo polymerization/condensation reactions to form larger molecules. (2) A fourth-order reaction model was used to describe the first 3 stages in the oxidation process, and the activation energies are 47.33, 18.69 and 9.00 kJ·mol−1 at 323–400, 400–605, 605–750 K, respectively. A three-dimensional diffusion model was applied to the fourth stage of the oxidation process, and the activation energy is 88.37 kJ·mol−1 at 750–860 K. A high softening point pitch was also produced for use as a coating of the graphite anode, and after it had been applied the capacity retention after 300 cycles increased from 51.54% to 79.07%.
2021, 36(1): 49-68.
doi: 10.1016/S1872-5805(21)60004-5
摘要：
Porous carbon-based electrode materials have been widely used in supercapacitors (SCs) because of their good physicochemical stability, high specific surface area, adjustable pore structure, and excellent electrical conductivity. The factors influencing their SC performance are analyzed, which include specific surface area, pore structure, surface heteroatoms, structural defects and electrode structure. The high surface area accessible to ions provides abundant active sites for their storage, while a suitable pore structure is important for the accommodation and diffusion of ions, thereby influencing the specific capacitance and rate performance of the electrodes. An appropriate pore size with a narrow distribution is required to increase the volumetric energy density while mesopores are favorable for ion transport, so a good balance between micro and mesopore volumes is important to improve both the energy and power densities of the SCs. Structural defects, surface heteroatoms and a rational electrode structural design all play significant roles in the capacitance performance.
Porous carbon-based electrode materials have been widely used in supercapacitors (SCs) because of their good physicochemical stability, high specific surface area, adjustable pore structure, and excellent electrical conductivity. The factors influencing their SC performance are analyzed, which include specific surface area, pore structure, surface heteroatoms, structural defects and electrode structure. The high surface area accessible to ions provides abundant active sites for their storage, while a suitable pore structure is important for the accommodation and diffusion of ions, thereby influencing the specific capacitance and rate performance of the electrodes. An appropriate pore size with a narrow distribution is required to increase the volumetric energy density while mesopores are favorable for ion transport, so a good balance between micro and mesopore volumes is important to improve both the energy and power densities of the SCs. Structural defects, surface heteroatoms and a rational electrode structural design all play significant roles in the capacitance performance.
2021, 36(1): 69-81.
doi: 10.1016/S1872-5805(21)60005-7
摘要：
Porous carbons are widely used in the energy storage and conversion field because of their excellent electrical conductivity, high specific surface area and superb electrochemical stability. The template method is one of the most advanced approaches to prepare porous carbons with well-defined pore structures and suitable pore size distributions. The pore formation mechanism and structure-property relationships of porous carbons obtained by template methods for supercapacitor electrodes are summarized. They include hard templates (magnesium-based, silica-based, zinc-based, calcium-based templates), soft templates (conventional soft template, ionic liquids, deep eutectic solvent) and self-templates (biomass, MOFs). Furthermore, the problems in tailoring the pore texture of porous carbons are clarified, and proposals are made for future research.
Porous carbons are widely used in the energy storage and conversion field because of their excellent electrical conductivity, high specific surface area and superb electrochemical stability. The template method is one of the most advanced approaches to prepare porous carbons with well-defined pore structures and suitable pore size distributions. The pore formation mechanism and structure-property relationships of porous carbons obtained by template methods for supercapacitor electrodes are summarized. They include hard templates (magnesium-based, silica-based, zinc-based, calcium-based templates), soft templates (conventional soft template, ionic liquids, deep eutectic solvent) and self-templates (biomass, MOFs). Furthermore, the problems in tailoring the pore texture of porous carbons are clarified, and proposals are made for future research.
2021, 36(3): 546-572.
doi: 10.1016/S1872-5805(21)60038-0
摘要：
Electrochemical capacitors, also called supercapacitors (SCs), have been gaining a more significant position as electrochemical energy storage devices in recent years. They are energy storage devices with a considerable power density, a satisfactory energy density and a long-life cycle, suitable for a large number of applications. The further development of these devices relies on providing suitable, low-cost, environmentally friendly, and abundant materials for use as the active materials in the electrodes. Among the current materials used, activated carbons have a superior performance. Their excellent electrochemical performance, high specific surface area, high adsorption, tunable surface chemistry, fast ion/electron transport, abundant functional moieties, low cost, and abundance have made them promising candidates as SC electrodes. These advantages can be enhanced if the activated carbons are prepared from biomass precursors. Recently, scientists have focused on biomass because it is abundant and renewable, low cost, simply processed, and environmentally friendly. The fundamentals of SCs as an electrochemical energy storage device are discussed and biomass from various sources is categorized and introduced. Finally, the activation techniques for these biomass precursors and their use as electrode materials for SCs are discussed.
Electrochemical capacitors, also called supercapacitors (SCs), have been gaining a more significant position as electrochemical energy storage devices in recent years. They are energy storage devices with a considerable power density, a satisfactory energy density and a long-life cycle, suitable for a large number of applications. The further development of these devices relies on providing suitable, low-cost, environmentally friendly, and abundant materials for use as the active materials in the electrodes. Among the current materials used, activated carbons have a superior performance. Their excellent electrochemical performance, high specific surface area, high adsorption, tunable surface chemistry, fast ion/electron transport, abundant functional moieties, low cost, and abundance have made them promising candidates as SC electrodes. These advantages can be enhanced if the activated carbons are prepared from biomass precursors. Recently, scientists have focused on biomass because it is abundant and renewable, low cost, simply processed, and environmentally friendly. The fundamentals of SCs as an electrochemical energy storage device are discussed and biomass from various sources is categorized and introduced. Finally, the activation techniques for these biomass precursors and their use as electrode materials for SCs are discussed.
2021, 36(6): 1016-1033.
doi: 10.1016/S1872-5805(21)60095-1
摘要：
With the development of electronic information technology, the use of microwaves in military and civilian fields is becoming more and more widespread. The corresponding electromagnetic radiation pollution has become a global concern. Numerous efforts have been made to synthesize thin electromagnetic wave absorbing materials with a low density, wide absorption bandwidth and high absorption. Carbon-based materials have great potential in electromagnetic wave absorption because of their lightweight, high attenuation ability, large specific surface area and excellent physicochemical stability. The attenuation theory of absorption materials and the factors that influence their absorption performance are provided first. Next, we summarize the research status of carbon materials with different morphologies (such as 0D carbon spheres, 1D carbon nanotubes, 2D carbon platelets, and 3D porous carbons) and their composites with various materials such as magnetic substances, ceramics, metal sulfides, MXene and conductive polymers. The synthesis methods, properties and attenuation mechanisms of these absorbers are highlighted, and prospects and challenges are considered.
With the development of electronic information technology, the use of microwaves in military and civilian fields is becoming more and more widespread. The corresponding electromagnetic radiation pollution has become a global concern. Numerous efforts have been made to synthesize thin electromagnetic wave absorbing materials with a low density, wide absorption bandwidth and high absorption. Carbon-based materials have great potential in electromagnetic wave absorption because of their lightweight, high attenuation ability, large specific surface area and excellent physicochemical stability. The attenuation theory of absorption materials and the factors that influence their absorption performance are provided first. Next, we summarize the research status of carbon materials with different morphologies (such as 0D carbon spheres, 1D carbon nanotubes, 2D carbon platelets, and 3D porous carbons) and their composites with various materials such as magnetic substances, ceramics, metal sulfides, MXene and conductive polymers. The synthesis methods, properties and attenuation mechanisms of these absorbers are highlighted, and prospects and challenges are considered.
2021, 36(3): 606-615.
doi: 10.1016/S1872-5805(21)60032-X
摘要：
A 3D assembly of nitrogen-doped carbon nanofibers (NCFs) derived from polyacrylonitrile was synthesized by a combined electrospinning/carbonization technique and was used as the positive current collector in lithium sulfur (Li-S) batteries containing a Li2S6 catholyte solution. The physical and electrochemical behavior of the NCFs were investigated and it was found that their electrochemical performances depended on the pyrolysis temperature. Of the samples carbonized at 800, 900 and 1 000 °C, those carbonized at 900 °C performed best, and delivered a reversible capacity of 875 mAh•g−1 at a high sulfur loading of 4.19 mg•cm2 and retained at 707 mAh•g−1 after 250 cycles at 0.2 C. The coulombic efficiency of the NCF-900@Li2S6 electrode was almost 98.55% over the entire cycle life. In addition, the capacity retention of the electrode reached 81.53% even at a high current density of 1 C for over 150 cycles. It was found that the NCFs carbonized at 900 °C had the highest electrical conductivity, which might be the dominant factor that determined its performance for use as a positive current collector.
A 3D assembly of nitrogen-doped carbon nanofibers (NCFs) derived from polyacrylonitrile was synthesized by a combined electrospinning/carbonization technique and was used as the positive current collector in lithium sulfur (Li-S) batteries containing a Li2S6 catholyte solution. The physical and electrochemical behavior of the NCFs were investigated and it was found that their electrochemical performances depended on the pyrolysis temperature. Of the samples carbonized at 800, 900 and 1 000 °C, those carbonized at 900 °C performed best, and delivered a reversible capacity of 875 mAh•g−1 at a high sulfur loading of 4.19 mg•cm2 and retained at 707 mAh•g−1 after 250 cycles at 0.2 C. The coulombic efficiency of the NCF-900@Li2S6 electrode was almost 98.55% over the entire cycle life. In addition, the capacity retention of the electrode reached 81.53% even at a high current density of 1 C for over 150 cycles. It was found that the NCFs carbonized at 900 °C had the highest electrical conductivity, which might be the dominant factor that determined its performance for use as a positive current collector.
2021, 36(1): 34-48.
doi: 10.1016/S1872-5805(21)60003-3
摘要：
Recent progress in the synthesis of carbon materials from biomass and coal/heavy oil waste and their use as the electrode materials of supercapacitors and Li-ion batteries is reviewed. The carbon precursors include seafood and agricultural waste, and coal and heavy oil by-products. The carbon materials include 0D carbon quantum dots, 1D carbon nanofibers, 2D carbon nanosheets, and 3D carbon frameworks. Techniques to tailor the carbon porosity/surface include KOH activation with and without self-templating, self-activation and/or in-situ templating, and heteroatom doping with N, O, P and their co-doping. The effects of porosity and heteroatom doping on the electrochemical performance are summarized. The challenges for the synthesis, microstructural tailoring of these materials and their potential use in supercapacitors and Li-ion batteries are analyzed.
Recent progress in the synthesis of carbon materials from biomass and coal/heavy oil waste and their use as the electrode materials of supercapacitors and Li-ion batteries is reviewed. The carbon precursors include seafood and agricultural waste, and coal and heavy oil by-products. The carbon materials include 0D carbon quantum dots, 1D carbon nanofibers, 2D carbon nanosheets, and 3D carbon frameworks. Techniques to tailor the carbon porosity/surface include KOH activation with and without self-templating, self-activation and/or in-situ templating, and heteroatom doping with N, O, P and their co-doping. The effects of porosity and heteroatom doping on the electrochemical performance are summarized. The challenges for the synthesis, microstructural tailoring of these materials and their potential use in supercapacitors and Li-ion batteries are analyzed.
2021, 36(1): 133-154.
doi: 10.1016/S1872-5805(21)60010-0
摘要：
As a natural abundant high-carbon resource, the use of coal to develop carbon nanomaterials is an important research topic. In recent years, a variety of carbon materials with different morphologies and nanotextures have been designed and constructed using coal and their derivatives as precursors, and their use in energy storage, catalysis, adsorption and absorption have been explored. State-of-the-art research on carbon nanomaterials derived from coals of different rank and their derivatives are summarized with specific attention to the synthesis strategies and structure control. The use of these coal-derived carbons for energy storage, such as secondary batteries and supercapacitors, is also discussed in terms of their structural features. The review aims to provide valuable insight into the present challenges and inspire new ideas for the development of advanced coal-derived carbon materials.
As a natural abundant high-carbon resource, the use of coal to develop carbon nanomaterials is an important research topic. In recent years, a variety of carbon materials with different morphologies and nanotextures have been designed and constructed using coal and their derivatives as precursors, and their use in energy storage, catalysis, adsorption and absorption have been explored. State-of-the-art research on carbon nanomaterials derived from coals of different rank and their derivatives are summarized with specific attention to the synthesis strategies and structure control. The use of these coal-derived carbons for energy storage, such as secondary batteries and supercapacitors, is also discussed in terms of their structural features. The review aims to provide valuable insight into the present challenges and inspire new ideas for the development of advanced coal-derived carbon materials.
2021, 36(1): 179-188.
doi: 10.1016/S1872-5805(21)60012-4
摘要：
We report a porous carbon material (NPCM) with a high N content as a high-performance supercapacitor electrode material which was prepared by a simple activation-doping process using Metaplexis Japonica shell as the carbon precursor, ammonium chloride as the nitrogen source and zinc chloride as the activation agent. Its high electrical conductivity, large ion-accessible surface area and fast ion transport ability make it possible to achieve a high mass loading of NPCM per area of the electrode and a high energy and high power density supercapacitor. An electrode with a low NPCM mass loading of 1 mg cm−2 has a gravimetric specific capacitance of 457 F g−1 and an areal specific capacitance of 47.8 μF cm−2. At a much high NPCM loading of 17.7 mg cm−2 it has a high gravimetric capacitance of 161 F g−1. Furthermore, an assembled NPCM//NPCM symmetric supercapacitor with an optimal NPCM loading of 12.3 mg cm−2 delivered a high specific energy of 12.5 Wh kg−1 at an ultrahigh power of 80 kW kg−1 in 1 mol L-1 Na2SO4. The achievement of such high-energy and high-power densities using NPCM will open exciting opportunities for carbon-based supercapacitors in many different applications.
We report a porous carbon material (NPCM) with a high N content as a high-performance supercapacitor electrode material which was prepared by a simple activation-doping process using Metaplexis Japonica shell as the carbon precursor, ammonium chloride as the nitrogen source and zinc chloride as the activation agent. Its high electrical conductivity, large ion-accessible surface area and fast ion transport ability make it possible to achieve a high mass loading of NPCM per area of the electrode and a high energy and high power density supercapacitor. An electrode with a low NPCM mass loading of 1 mg cm−2 has a gravimetric specific capacitance of 457 F g−1 and an areal specific capacitance of 47.8 μF cm−2. At a much high NPCM loading of 17.7 mg cm−2 it has a high gravimetric capacitance of 161 F g−1. Furthermore, an assembled NPCM//NPCM symmetric supercapacitor with an optimal NPCM loading of 12.3 mg cm−2 delivered a high specific energy of 12.5 Wh kg−1 at an ultrahigh power of 80 kW kg−1 in 1 mol L-1 Na2SO4. The achievement of such high-energy and high-power densities using NPCM will open exciting opportunities for carbon-based supercapacitors in many different applications.
2022, 37(1): 59-92.
doi: 10.1016/S1872-5805(22)60579-1
摘要：
Because of damage to the environment and the energy crisis, the storage and use of sustainable energy, such as solar and wind, has become urgent. Much attention has been given to the use of electrochemical energy storage (EES) devices in storing this energy. Electrode materials are critical to the performance of these devices, and carbon-based nanomaterials have become extremely promising components because of their unique and outstanding advantages. The structure design and controllable synthesis of electrode materials determine the electrochemical performance of EES to a large extent. In this review, strategies for carbon-based materials of different dimensionalities are summarized and their uses in different EES devices are given, providing an in-depth understanding of the relationship between material structure and electrochemical performance. Prospects for the design and synthesis of carbon-based nanomaterials with exceptional performance for EES devices are given.
Because of damage to the environment and the energy crisis, the storage and use of sustainable energy, such as solar and wind, has become urgent. Much attention has been given to the use of electrochemical energy storage (EES) devices in storing this energy. Electrode materials are critical to the performance of these devices, and carbon-based nanomaterials have become extremely promising components because of their unique and outstanding advantages. The structure design and controllable synthesis of electrode materials determine the electrochemical performance of EES to a large extent. In this review, strategies for carbon-based materials of different dimensionalities are summarized and their uses in different EES devices are given, providing an in-depth understanding of the relationship between material structure and electrochemical performance. Prospects for the design and synthesis of carbon-based nanomaterials with exceptional performance for EES devices are given.
2021, 36(1): 93-105.
doi: 10.1016/S1872-5805(21)60007-0
摘要：
Raman spectroscopy is a fast, non-destructive and high-resolution characterization tool based on laser physics that can be applied to a wide range of materials science problems. It has proven to be an effective tool in studying phase transitions induced by variables such as temperature, pressure or electrochemical reactions. In-situ Raman spectroscopy can be used to track any microstructural changes of the electrode materials and interface reactions in alkali metal-ion batteries during charging and discharging. Carbon materials have become the most widely used anode materials for lithium-ion batteries because of their good electrochemical reversibility, excellent stability, low electrochemical charge/discharge potential platform, and low cost. The use of in-situ Raman spectroscopy in understanding the reactions occurring in alkali metal-ion batteries using carbon anode materials is summarized with a focus on the energy storage mechanism in Li+/Na+/K+ ion batteries using carbon materials such as graphite and hard carbon as the anode materials. The effects of size, stress, doping, and the solvation-assisted co-intercalation of Li+/Na+/K+ ions on the energy storage behavior in alkali metal-ion batteries are analyzed. Based on the strength and weakness of in-situ Raman spectroscopy, its combination with AFM, in situ XRD and other high-resolution in situ technologies is used to reveal the energy storage mechanisms.
Raman spectroscopy is a fast, non-destructive and high-resolution characterization tool based on laser physics that can be applied to a wide range of materials science problems. It has proven to be an effective tool in studying phase transitions induced by variables such as temperature, pressure or electrochemical reactions. In-situ Raman spectroscopy can be used to track any microstructural changes of the electrode materials and interface reactions in alkali metal-ion batteries during charging and discharging. Carbon materials have become the most widely used anode materials for lithium-ion batteries because of their good electrochemical reversibility, excellent stability, low electrochemical charge/discharge potential platform, and low cost. The use of in-situ Raman spectroscopy in understanding the reactions occurring in alkali metal-ion batteries using carbon anode materials is summarized with a focus on the energy storage mechanism in Li+/Na+/K+ ion batteries using carbon materials such as graphite and hard carbon as the anode materials. The effects of size, stress, doping, and the solvation-assisted co-intercalation of Li+/Na+/K+ ions on the energy storage behavior in alkali metal-ion batteries are analyzed. Based on the strength and weakness of in-situ Raman spectroscopy, its combination with AFM, in situ XRD and other high-resolution in situ technologies is used to reveal the energy storage mechanisms.
2012, 27(05): 321-336.
Abstract:
2011, 26(01): 71-80.
Abstract:
Editor-in-Chief： Chun-xiang Lu, Ph.D
Charged by：Chinese Academy of Sciences
Sponsored by：Institute of Coal Chemistry, Chinese Academy of Sciences
Published by：Science Press, Elsevier
CN 14-1407/TQ
ISSN 2097-1605
eISSN 1872-5805
Since 1985 Bimonthly
CiteScore: 6.1
IF: 5.7
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