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, 最新更新时间 , doi: 10.1016/S1872-5805(23)60724-3
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摘要:
One of the most important research areas that has captured global attention is the replacement of graphite anode with other carbon materials such as hard carbon, activated carbon, carbon nanotubes, graphene, porous carbon, and carbon fiber. Although such materials have shown better electrochemical performance for lithium storage compared to graphite, their is plenty of room for improvement. One of the most effective approaches is to dope heteroatoms (e. g. nitrogen) in the structure of carbon materials to enhance their electrochemical performance when used as anode in lithium ion batteries. In this review paper, we first describe how N doping has a positive effect on lithium storage and then provide numerous selected examples of this approach being applied to various carbon materials. Then, in addition to the conventional characterization methods, the specific characterization of doped N in the structure of different carbon materials through X-ray photoelectron spectroscopy and scanning tunneling microscopy is presented, as they are able to characterize N in these structures with high (atomic) resolution. Finally, a statistical analysis is performed to discover the influence that the amount of doped N has on the specific capacity of N-doped carbon materials.
One of the most important research areas that has captured global attention is the replacement of graphite anode with other carbon materials such as hard carbon, activated carbon, carbon nanotubes, graphene, porous carbon, and carbon fiber. Although such materials have shown better electrochemical performance for lithium storage compared to graphite, their is plenty of room for improvement. One of the most effective approaches is to dope heteroatoms (e. g. nitrogen) in the structure of carbon materials to enhance their electrochemical performance when used as anode in lithium ion batteries. In this review paper, we first describe how N doping has a positive effect on lithium storage and then provide numerous selected examples of this approach being applied to various carbon materials. Then, in addition to the conventional characterization methods, the specific characterization of doped N in the structure of different carbon materials through X-ray photoelectron spectroscopy and scanning tunneling microscopy is presented, as they are able to characterize N in these structures with high (atomic) resolution. Finally, a statistical analysis is performed to discover the influence that the amount of doped N has on the specific capacity of N-doped carbon materials.
, 最新更新时间 , doi: 10.1016/S1872-5805(22)60644-9
摘要:
碳点（CDs）是一种新兴的碳纳米材料，因其高比表面积、良好的分散性、丰富的表面官能团、低生物毒性和光致发光特性而受到了研究者的广泛关注。然而，低成本、大规模和绿色合成CDs仍面临挑战。本工作基于生物质玉米芯特殊的天然孔隙结构，经直接炭化制备具有定向、贯通微纳米孔道的多孔三维电极材料，内外表面同时发生电化学氧化高效制备CDs 1 A恒电流下，每克电极材料制备CDs速率达到了79.83 mg h−1。将制备的CDs与氧化石墨烯（GO）水热复合得到复合气凝胶CDs/rGO材料，经热处理后应用于钠离子电池。在1 A g−1下循环1000圈仍保持263.3 mAh g−1的容量。采用生物质玉米芯出发简单高效制备碳点，为CDs的大规模绿色制备和应用提供了新的途径和思路。
碳点（CDs）是一种新兴的碳纳米材料，因其高比表面积、良好的分散性、丰富的表面官能团、低生物毒性和光致发光特性而受到了研究者的广泛关注。然而，低成本、大规模和绿色合成CDs仍面临挑战。本工作基于生物质玉米芯特殊的天然孔隙结构，经直接炭化制备具有定向、贯通微纳米孔道的多孔三维电极材料，内外表面同时发生电化学氧化高效制备CDs 1 A恒电流下，每克电极材料制备CDs速率达到了79.83 mg h−1。将制备的CDs与氧化石墨烯（GO）水热复合得到复合气凝胶CDs/rGO材料，经热处理后应用于钠离子电池。在1 A g−1下循环1000圈仍保持263.3 mAh g−1的容量。采用生物质玉米芯出发简单高效制备碳点，为CDs的大规模绿色制备和应用提供了新的途径和思路。
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60731-0
摘要:
The synthesis and preparation of high-rate and long-life anode materials for sodium ion batteries (SIBs) have attracted more attention. However, the slow kinetics and massive volume growth are still the weaknesses of SIBs. Metal-organic frame and MoS2 have excellent properties for SIBs. Herein, flower-like Co9S8/MoS2 composites were designed and constructed via a simultaneous vulcanization-carbonization method at different using Co-ZIF as a precursor and adding Mo source. The effect of heterojunction on the diffusion kinetics was analyzed using density functional theory (DFT). The computational results indicate that the electronic structure is reshaped at the interface of the heterogeneous structure, exhibits typical metal properties, and exhibits enhanced electronic conductivity. In addition, the anode material Co9S8/MoS2 synthesized at 700 °C has stable structure and excellent electrochemical performance among the three samples. It is worth noting that the discharge capacity of Co9S8/MoS2-700 can fully recover from 368 mAh g−1 to 571 mAh g−1 and then stabilize at 543 mAh g−1 when the current density is restored from 4000 to 40 mA g−1. Therefore, this work offers some ideas for the rational preparation of heterojunction material, and helps in the design of anode material for composite high-performance metal sodium ion batteries.
The synthesis and preparation of high-rate and long-life anode materials for sodium ion batteries (SIBs) have attracted more attention. However, the slow kinetics and massive volume growth are still the weaknesses of SIBs. Metal-organic frame and MoS2 have excellent properties for SIBs. Herein, flower-like Co9S8/MoS2 composites were designed and constructed via a simultaneous vulcanization-carbonization method at different using Co-ZIF as a precursor and adding Mo source. The effect of heterojunction on the diffusion kinetics was analyzed using density functional theory (DFT). The computational results indicate that the electronic structure is reshaped at the interface of the heterogeneous structure, exhibits typical metal properties, and exhibits enhanced electronic conductivity. In addition, the anode material Co9S8/MoS2 synthesized at 700 °C has stable structure and excellent electrochemical performance among the three samples. It is worth noting that the discharge capacity of Co9S8/MoS2-700 can fully recover from 368 mAh g−1 to 571 mAh g−1 and then stabilize at 543 mAh g−1 when the current density is restored from 4000 to 40 mA g−1. Therefore, this work offers some ideas for the rational preparation of heterojunction material, and helps in the design of anode material for composite high-performance metal sodium ion batteries.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60714-0
摘要:
较低的体积能量密度限制了当前电化学电容器的应用，而提高体积能量密度的关键在于发展具有致密化储能特性的多孔炭材料。目前，毛细致密化已成为平衡多孔炭密度和孔隙率从而提高材料体积比电容的主要方法，但仍在孔结构的精细调控方面存在不足，制约了毛细致密化多孔炭与高电压离子液体的兼容性。本文提出了碘化钾（KI）辅助的毛细致密化策略，通过在石墨烯网络中预载KI来控制毛细致密化过程，实现了对孔结构的有效调控。同时电化学性能表征结果表明KI具有增加离子到达表面积和提供赝电容的作用。基于此，所制碘化钾/石墨烯材料的密度达到0.96 g cm−3，在离子液体中的体积比电容为115 F cm−3。由该材料所组装的电化学电容器可以提供19.6 Wh L−1的体积能量密度。
较低的体积能量密度限制了当前电化学电容器的应用，而提高体积能量密度的关键在于发展具有致密化储能特性的多孔炭材料。目前，毛细致密化已成为平衡多孔炭密度和孔隙率从而提高材料体积比电容的主要方法，但仍在孔结构的精细调控方面存在不足，制约了毛细致密化多孔炭与高电压离子液体的兼容性。本文提出了碘化钾（KI）辅助的毛细致密化策略，通过在石墨烯网络中预载KI来控制毛细致密化过程，实现了对孔结构的有效调控。同时电化学性能表征结果表明KI具有增加离子到达表面积和提供赝电容的作用。基于此，所制碘化钾/石墨烯材料的密度达到0.96 g cm−3，在离子液体中的体积比电容为115 F cm−3。由该材料所组装的电化学电容器可以提供19.6 Wh L−1的体积能量密度。
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60725-5
摘要:
Sodium-ion batteries (SIBs) have received extensive research interests as an important supplement of lithium-ion batteries in the electrochemical energy storage field by virtue of abundant reserves and low-cost advantages of sodium element. In the past few years, carbon and their composite materials as anode materials have shown excellent sodium storage properties through structural design and composition regulation. The increasing popularity of wearable electronics has put forward higher requirements for electrode materials. Free-standing electrode is able to eliminate the massive use of electrochemical inactive binders and conductive additives, thereby favorably increasing the overall energy density of the battery system. In this review, the research progress of carbon materials (such as carbon nanofibers, carbon nanotubes, graphene, etc.) and their composites (metallic compounds and alloy-type materials) are summarized. The preparation strategies and electrochemical properties of free-standing carbon-based anodes with and without substrates are categorized and reviewed. Finally, the perspectives about research directions and future developments of free-standing carbon-based anodes for SIBs are proposed.
Sodium-ion batteries (SIBs) have received extensive research interests as an important supplement of lithium-ion batteries in the electrochemical energy storage field by virtue of abundant reserves and low-cost advantages of sodium element. In the past few years, carbon and their composite materials as anode materials have shown excellent sodium storage properties through structural design and composition regulation. The increasing popularity of wearable electronics has put forward higher requirements for electrode materials. Free-standing electrode is able to eliminate the massive use of electrochemical inactive binders and conductive additives, thereby favorably increasing the overall energy density of the battery system. In this review, the research progress of carbon materials (such as carbon nanofibers, carbon nanotubes, graphene, etc.) and their composites (metallic compounds and alloy-type materials) are summarized. The preparation strategies and electrochemical properties of free-standing carbon-based anodes with and without substrates are categorized and reviewed. Finally, the perspectives about research directions and future developments of free-standing carbon-based anodes for SIBs are proposed.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60722-X
摘要:
As the massive emission of CO2 caused by the consumption of carbon has become the focus of human society, the development of renewable energy and the reduction emission of CO2 has become one of the most urgent issues to deal with in the world. As the most ideal clean energy on earth, solar energy has become a hot topic of current research. If abundant solar energy can be used to convert carbon dioxide into valued carbon-based chemicals, these two problems can be solved at the same time. There are many literatures on photocatalysis or thermal catalysis in the reduction of CO2. However, there is little research on photothermal catalysis in the reduction of CO2. In this paper, the research status of photothermal catalysis in the reduction of CO2 is summarized, showing the concept and principle of photothermal catalysis in the reduction of CO2, the classification of catalysts (new carbon materials, oxide materials, metal sulfide materials, MOF materials, layered double hydroxide materials), the modification of catalysts, and their applications in reduction of CO2. Finally, the development trend of the catalyst is forecasted. The rational development of carbon-based chemicals may help us reduce the consumption of traditional energy, reduce carbon emissions and realize the recycling of carbon.
As the massive emission of CO2 caused by the consumption of carbon has become the focus of human society, the development of renewable energy and the reduction emission of CO2 has become one of the most urgent issues to deal with in the world. As the most ideal clean energy on earth, solar energy has become a hot topic of current research. If abundant solar energy can be used to convert carbon dioxide into valued carbon-based chemicals, these two problems can be solved at the same time. There are many literatures on photocatalysis or thermal catalysis in the reduction of CO2. However, there is little research on photothermal catalysis in the reduction of CO2. In this paper, the research status of photothermal catalysis in the reduction of CO2 is summarized, showing the concept and principle of photothermal catalysis in the reduction of CO2, the classification of catalysts (new carbon materials, oxide materials, metal sulfide materials, MOF materials, layered double hydroxide materials), the modification of catalysts, and their applications in reduction of CO2. Finally, the development trend of the catalyst is forecasted. The rational development of carbon-based chemicals may help us reduce the consumption of traditional energy, reduce carbon emissions and realize the recycling of carbon.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60721-8
摘要:
Supercapacitors fabricated using fiber materials are becoming noticeable electrochemical energy storage devices as they are flexible, light weight and have high energy density. These are used in electronic systems, such as information sensing, data computation and communication. These flexible supercapacitors are applied in electronic textiles because these fabric-based supercapacitors (SCs) can achieve higher power density than standard parallel plate capacitors and batteries. In this review, the effects of carbon nanotubes (CNTs), graphene and poly(3,4- ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT:PSS) on the electrochemical performance of fibers based on their compositions, spinning and fabrication conditions have been explained in detail in the context of wearable energy storage devices.
Supercapacitors fabricated using fiber materials are becoming noticeable electrochemical energy storage devices as they are flexible, light weight and have high energy density. These are used in electronic systems, such as information sensing, data computation and communication. These flexible supercapacitors are applied in electronic textiles because these fabric-based supercapacitors (SCs) can achieve higher power density than standard parallel plate capacitors and batteries. In this review, the effects of carbon nanotubes (CNTs), graphene and poly(3,4- ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT:PSS) on the electrochemical performance of fibers based on their compositions, spinning and fabrication conditions have been explained in detail in the context of wearable energy storage devices.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60713-9
摘要:
As the sulfur host as a reactor for redox reactions and determines the electrochemical properties of the sulfur cathode, tailor-made fabrication of sulfur host is very effective to solve the main challenges of lithium-sulfur (Li-S) batteries, such as the shuttle effect and sluggish redox kinetics. Under this guidance, sulfur is in-situ confined in a hollow thin-walled C/Mo2C reactor with size smaller than 7 nm, in which these nanosized primary particles are connected with each other forming secondary microsized particles. In such composites, the nanoscale sulfur core and continuous conductive network can facilitate lithium-ion and electron transport. Moreover, the microporous C/Mo2C shell can mitigate the outward diffusion of polysulfides via the physical/chemical obstruction and enhance redox kinetics through effective catalysis conversion of polysulfides. Stem from these merits, the S@C/Mo2C cathode materials can achieve a high reversible capacity of 1210 mA h g−1 at 0.5 C with a low capacity fading rate of 0.127% per cycle over 300 cycles and high rate performance (780 mA h g−1 at 3.0 C). The present work may shed light on designing advanced sulfur host for Li-S batteries with high rate performance and high cycle stability.
As the sulfur host as a reactor for redox reactions and determines the electrochemical properties of the sulfur cathode, tailor-made fabrication of sulfur host is very effective to solve the main challenges of lithium-sulfur (Li-S) batteries, such as the shuttle effect and sluggish redox kinetics. Under this guidance, sulfur is in-situ confined in a hollow thin-walled C/Mo2C reactor with size smaller than 7 nm, in which these nanosized primary particles are connected with each other forming secondary microsized particles. In such composites, the nanoscale sulfur core and continuous conductive network can facilitate lithium-ion and electron transport. Moreover, the microporous C/Mo2C shell can mitigate the outward diffusion of polysulfides via the physical/chemical obstruction and enhance redox kinetics through effective catalysis conversion of polysulfides. Stem from these merits, the S@C/Mo2C cathode materials can achieve a high reversible capacity of 1210 mA h g−1 at 0.5 C with a low capacity fading rate of 0.127% per cycle over 300 cycles and high rate performance (780 mA h g−1 at 3.0 C). The present work may shed light on designing advanced sulfur host for Li-S batteries with high rate performance and high cycle stability.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60705-X
摘要:
An anodized carbon fiber tow is sized continuously. The effects of aqueous polyurethane as the sizing agent for enhancing the interfacial properties of carbon fiber reinforced polyurethane composite has been investigated by mutliple techniques, including interlaminar shear strength (ILSS), elemental and functional group analysis, thermal gravimetric analysis, and differential scanning calorimetry. The results show the polyurethane sizing agent can significantly improve the interfacial properties of the composites. The ILSS of the sized carbon fiber reinforced composite is increased by 17.5% (from 39.5 to 46.4 MPa) compared with that of the oxidized carbon fiber reinforced counterpart. Treating the sized carbon fiber reinforced composite at 170 °C can further increase the ILSS by 9.5%, to 50.8 MPa. It is considered that the sizing agent can interact with the oxygen-contained functional groups on the oxidized carbon fiber surface and form hydrogen bonds with the matrix resin. Upon heating at 170 °C, the blocking groups in the sizing agent are unblocked to expose the isocyanate roots that can react with the carbamate of the matrix to generate allophanate. It can draw the conclusions that the polyurethane sizing agent is suitable to improve the interfacial performance of carbon fiber reinforced polyurethane resin composites. Unsealing the sizing agent at high temperature after curing can further improve the interfacial performance of the composite.
An anodized carbon fiber tow is sized continuously. The effects of aqueous polyurethane as the sizing agent for enhancing the interfacial properties of carbon fiber reinforced polyurethane composite has been investigated by mutliple techniques, including interlaminar shear strength (ILSS), elemental and functional group analysis, thermal gravimetric analysis, and differential scanning calorimetry. The results show the polyurethane sizing agent can significantly improve the interfacial properties of the composites. The ILSS of the sized carbon fiber reinforced composite is increased by 17.5% (from 39.5 to 46.4 MPa) compared with that of the oxidized carbon fiber reinforced counterpart. Treating the sized carbon fiber reinforced composite at 170 °C can further increase the ILSS by 9.5%, to 50.8 MPa. It is considered that the sizing agent can interact with the oxygen-contained functional groups on the oxidized carbon fiber surface and form hydrogen bonds with the matrix resin. Upon heating at 170 °C, the blocking groups in the sizing agent are unblocked to expose the isocyanate roots that can react with the carbamate of the matrix to generate allophanate. It can draw the conclusions that the polyurethane sizing agent is suitable to improve the interfacial performance of carbon fiber reinforced polyurethane resin composites. Unsealing the sizing agent at high temperature after curing can further improve the interfacial performance of the composite.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60704-8
摘要:
In this study, a novel pantograph carbon slider (PCS) was designed by incorporating sulfonated graphene (SG), resulting in the enhancement of mechanical and wear performances of the slider. The PCS was prepared through mold pressing, hot extrusion and roasting. A mock current-carrying wear test showed that the wear rate of the PCS reinforced by 1 wt % SG was lowered by 50.0% in the normal environment and 51.0% in a rainy weather environment, compared with the control group. In addition, the flexural strength of the samples with SG was 41.8% higher than to those without SG. Moreover, the dragging effect of SG decreased the number of random cracks and increased the compactness of fracture surface of the slider materials. These changes markedly inhibited the electro-erosion of the PCS, thus improving mechanical and wear resistance significantly.
In this study, a novel pantograph carbon slider (PCS) was designed by incorporating sulfonated graphene (SG), resulting in the enhancement of mechanical and wear performances of the slider. The PCS was prepared through mold pressing, hot extrusion and roasting. A mock current-carrying wear test showed that the wear rate of the PCS reinforced by 1 wt % SG was lowered by 50.0% in the normal environment and 51.0% in a rainy weather environment, compared with the control group. In addition, the flexural strength of the samples with SG was 41.8% higher than to those without SG. Moreover, the dragging effect of SG decreased the number of random cracks and increased the compactness of fracture surface of the slider materials. These changes markedly inhibited the electro-erosion of the PCS, thus improving mechanical and wear resistance significantly.
, 最新更新时间 , doi: 10.1016/S1872-5805(22)60647-4
摘要:
Graphene/Ni-NiO@C was prepared by dissolving nickel acetate and glucose in water, mixed with a graphene oxide (GO) aqueous suspension, hydrothermal treated at 180 °C for 24 h, carbonized at 700 °C for 3h in Ar and calcined at 300 °C for 3 h in air. Results indicated that Ni(OH)2 formed during hydrothermal treatment was coated with char derived from glucose and converted to metallic Ni in carbonization, which was partly oxidized to NiO in calcination. When used as the anode material of a lithium-ion battery, it exhibited a high initial capacity of 711.6 mA h g−1, which increased to 772.1 mA h g−1 after 300 cycles. As a comparison, the sample without adding GO had a much lower initial capacity of 584.7 mA h g−1, which decreased to 148.8 mA h g−1 after 300 cycles. Carbon coating on Ni-NiO nanoparticles inhibited their aggregation. GO addition led to the formation of a conducting network, alleviated the large volume expansion during lithiation, restrained the electrode cracking during cycling and increased surface area for easy access of the electrolyte. These factors jointly contributed to the apparent improvement in the electrochemical performance of the graphene/Ni-NiO@C anode.
Graphene/Ni-NiO@C was prepared by dissolving nickel acetate and glucose in water, mixed with a graphene oxide (GO) aqueous suspension, hydrothermal treated at 180 °C for 24 h, carbonized at 700 °C for 3h in Ar and calcined at 300 °C for 3 h in air. Results indicated that Ni(OH)2 formed during hydrothermal treatment was coated with char derived from glucose and converted to metallic Ni in carbonization, which was partly oxidized to NiO in calcination. When used as the anode material of a lithium-ion battery, it exhibited a high initial capacity of 711.6 mA h g−1, which increased to 772.1 mA h g−1 after 300 cycles. As a comparison, the sample without adding GO had a much lower initial capacity of 584.7 mA h g−1, which decreased to 148.8 mA h g−1 after 300 cycles. Carbon coating on Ni-NiO nanoparticles inhibited their aggregation. GO addition led to the formation of a conducting network, alleviated the large volume expansion during lithiation, restrained the electrode cracking during cycling and increased surface area for easy access of the electrolyte. These factors jointly contributed to the apparent improvement in the electrochemical performance of the graphene/Ni-NiO@C anode.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60709-7
摘要:
Mesophase pitch-based carbon fibers (MPCFs) have the characteristics of high modulus, low resistivity and high thermal conductivity, so it has broad application prospects in many fields. High-performance carbon fibers were prepared from naphthalene-based mesophase pitches synthesized by HF/BF3 catalytic one-step method (AR-MP) and AlCl3 catalytic two-step method (N-MP), respectively. These two mesophase pitches, and spun pitch fibers, pre-oxidized fibers carbonized fibers and graphitized fibers produced from them were characterized by TG-MS, FT-IR, 13C-NMR, MALDI-TOF-MS, XRD, SEM and elemental analysis. The molecular structures and properties of mesophase pitches prepared by different catalytic polymerization processes were compared, and the effects of molecular structure differences of mesophase pitches on the structure and properties of carbon fibers were further explored. In comparison to N-MP, AR-MP possesses a rod-like semi-rigid molecular configuration containing more naphthenic structures and methyl side chains. The pre-oxidized fibers derived from AR-MP show better carbon layer orientation, thus their graphitized fibers have higher thermal conductivity of 716 W/m·K. N-MP with higher aromaticity possesses a disc-like rigid molecular configuration. Therefore, the graphitized fibers prepared from N-MP have higher tensile strength of 3.47 GPa due to their fewer resulted defects during the preparation. The molecular structures of AR-MP and N-MP have an obvious influence on the structure and properties of their graphited fibers.
Mesophase pitch-based carbon fibers (MPCFs) have the characteristics of high modulus, low resistivity and high thermal conductivity, so it has broad application prospects in many fields. High-performance carbon fibers were prepared from naphthalene-based mesophase pitches synthesized by HF/BF3 catalytic one-step method (AR-MP) and AlCl3 catalytic two-step method (N-MP), respectively. These two mesophase pitches, and spun pitch fibers, pre-oxidized fibers carbonized fibers and graphitized fibers produced from them were characterized by TG-MS, FT-IR, 13C-NMR, MALDI-TOF-MS, XRD, SEM and elemental analysis. The molecular structures and properties of mesophase pitches prepared by different catalytic polymerization processes were compared, and the effects of molecular structure differences of mesophase pitches on the structure and properties of carbon fibers were further explored. In comparison to N-MP, AR-MP possesses a rod-like semi-rigid molecular configuration containing more naphthenic structures and methyl side chains. The pre-oxidized fibers derived from AR-MP show better carbon layer orientation, thus their graphitized fibers have higher thermal conductivity of 716 W/m·K. N-MP with higher aromaticity possesses a disc-like rigid molecular configuration. Therefore, the graphitized fibers prepared from N-MP have higher tensile strength of 3.47 GPa due to their fewer resulted defects during the preparation. The molecular structures of AR-MP and N-MP have an obvious influence on the structure and properties of their graphited fibers.
, 最新更新时间 , doi: 10.1016/S1872-5805(21)60059-8
摘要:
Graphite is one of the most promising anode materials for potassium-ion batteries (PIBs) due to its low cost and stable discharge plateau. However, its poor rate performance still needs to be improved. Herein, a novel graphitic anode was designed from commercial mesocarbon microbeads (MCMB) by KOH treatment. Through limited oxidation and slight intercalation, an expanded layer with enlarged interlayer spacing formed on the surface of MCMB, by which the K+ diffusion rate was significantly improved. When served as the PIB anode, this modified MCMB delivered a high plateau capacity below 0.25 V (271 mAh g−1), superior rate capability (160 mAh g−1 at 1.0 A g−1), excellent cycling stability (about 184 mAh g−1 after 100 cycles at 0.1 A g−1), and high initial coulombic efficiency with carboxymethyl cellulose as binder (79.2%). This work provides a facile strategy to prepare graphitic materials with superior potassium storage property.
Graphite is one of the most promising anode materials for potassium-ion batteries (PIBs) due to its low cost and stable discharge plateau. However, its poor rate performance still needs to be improved. Herein, a novel graphitic anode was designed from commercial mesocarbon microbeads (MCMB) by KOH treatment. Through limited oxidation and slight intercalation, an expanded layer with enlarged interlayer spacing formed on the surface of MCMB, by which the K+ diffusion rate was significantly improved. When served as the PIB anode, this modified MCMB delivered a high plateau capacity below 0.25 V (271 mAh g−1), superior rate capability (160 mAh g−1 at 1.0 A g−1), excellent cycling stability (about 184 mAh g−1 after 100 cycles at 0.1 A g−1), and high initial coulombic efficiency with carboxymethyl cellulose as binder (79.2%). This work provides a facile strategy to prepare graphitic materials with superior potassium storage property.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60708-5
摘要:
As a key material in nuclear reactors, the microstructure of nuclear graphite is affected by the high-flux irradiation in reactors. The damage behavior of nuclear graphite by irradiation is important for the safe operation of reactors. In order to understand the damage behavior of nuclear graphite by irradiation, IG-110 nuclear graphite, as a representative of nuclear graphite, was chosen to investigate the evolution of morphology and microstructure caused by 7 MeV Xe26+ irradiation. The topography and microstructure of IG-110 were characterized by scanning electron microscopy, atomic force microscopy, grazing incidence X-ray diffraction, Raman spectroscopy and nano-indentation. Results indicate that after 7 MeV Xe26+ irradiation at a dose of 0.11 dpa, the ridge-like structure appears on the surface of the IG-110 graphite, mainly in the binder region, and the surface roughness increases slightly. With a further increase of the irradiation dose, the ridge-like structure also appears in the filler region. At a dose of 0.55 dpa, the shrinkage of pores increases accompanied by closing of pores, and the surface roughness also increases. The changes in topography and microstructure of IG-110 graphite caused by irradiation are attributed to the expansion of graphite along the C-axis direction. Defect density and the degree of in-plane disorder in the graphene sheets increases with the increase of irradiation dose. The mechanical properties of IG-110 graphite increase first then decrease with increasing the irradiation dose. The increase of mechanical properties is caused by dislocation pinning and closing of fine pores, while the decrease of mechanical properties is attributed to the increase of porosity and the generation of the amorphous structure.
As a key material in nuclear reactors, the microstructure of nuclear graphite is affected by the high-flux irradiation in reactors. The damage behavior of nuclear graphite by irradiation is important for the safe operation of reactors. In order to understand the damage behavior of nuclear graphite by irradiation, IG-110 nuclear graphite, as a representative of nuclear graphite, was chosen to investigate the evolution of morphology and microstructure caused by 7 MeV Xe26+ irradiation. The topography and microstructure of IG-110 were characterized by scanning electron microscopy, atomic force microscopy, grazing incidence X-ray diffraction, Raman spectroscopy and nano-indentation. Results indicate that after 7 MeV Xe26+ irradiation at a dose of 0.11 dpa, the ridge-like structure appears on the surface of the IG-110 graphite, mainly in the binder region, and the surface roughness increases slightly. With a further increase of the irradiation dose, the ridge-like structure also appears in the filler region. At a dose of 0.55 dpa, the shrinkage of pores increases accompanied by closing of pores, and the surface roughness also increases. The changes in topography and microstructure of IG-110 graphite caused by irradiation are attributed to the expansion of graphite along the C-axis direction. Defect density and the degree of in-plane disorder in the graphene sheets increases with the increase of irradiation dose. The mechanical properties of IG-110 graphite increase first then decrease with increasing the irradiation dose. The increase of mechanical properties is caused by dislocation pinning and closing of fine pores, while the decrease of mechanical properties is attributed to the increase of porosity and the generation of the amorphous structure.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60732-2
摘要:
2D laminated carbon cloth as reinforcement, furfurone resin mixed with three inorganic powders such as silicon powder, carbon powder and silicon carbide powder, carbon/carbon-silicon carbide (C/C-SiC) composites were prepared through impregnation, hot-pressing with curing, carbonization and high-temperature heat treatment processes. The effects of addition of silicon powder, carbon powder and silicon carbide powder as well as subsequent chemical vapor infiltration (CVI) treatment on density, microstructure and bending strength of C/C-SiC composites were studied by scanning electron microscope (SEM), multifunctional density , X-ray diffraction (XRD) and universal mechanical testing machine. The results showed that the silicon carbide particles formed by the addition of silicon powder, carbon powder and silicon carbide powder had the effect of particle dispersion enhancement on the composite material. Under three-point bending load, C/C-SiC composites show pseudoplastic fracture mode and interlaminar cracking. After 10 h CVI treatment of C/C-SiC composites, the pyrolytic carbon can be used as the interface between carbon fiber and resin carbon matrix. The density and flexural strength of C/C-SiC composites were maximum increased by 4.98% and 38.86%, respectively.
2D laminated carbon cloth as reinforcement, furfurone resin mixed with three inorganic powders such as silicon powder, carbon powder and silicon carbide powder, carbon/carbon-silicon carbide (C/C-SiC) composites were prepared through impregnation, hot-pressing with curing, carbonization and high-temperature heat treatment processes. The effects of addition of silicon powder, carbon powder and silicon carbide powder as well as subsequent chemical vapor infiltration (CVI) treatment on density, microstructure and bending strength of C/C-SiC composites were studied by scanning electron microscope (SEM), multifunctional density , X-ray diffraction (XRD) and universal mechanical testing machine. The results showed that the silicon carbide particles formed by the addition of silicon powder, carbon powder and silicon carbide powder had the effect of particle dispersion enhancement on the composite material. Under three-point bending load, C/C-SiC composites show pseudoplastic fracture mode and interlaminar cracking. After 10 h CVI treatment of C/C-SiC composites, the pyrolytic carbon can be used as the interface between carbon fiber and resin carbon matrix. The density and flexural strength of C/C-SiC composites were maximum increased by 4.98% and 38.86%, respectively.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60730-9
摘要:
MXene is a sort of revolutionary two-dimensional material that possesses distinctive laminated structure and composition of transition metal carbides. It exhibits special physicochemical characteristics including large specific surface area, admirable conductivity, mechanical property and photothermal behaviors, which enable it to represent application value. Furthermore, for pursuing broader application, MXene is usually compounded with carbon-based materials to strengthen comprehensive performances. Therefore, MXene and MXene- carbon based composites has been attracted more attention in various fields such as electronics, biosensors and biomedicine over the past few years. In this review, the fabrication, modification and biomedical applications concerning MXene and MXene-carbon based materials will be introduced. In particular, this review will focus on biomedical applications of MXene and MXene-carbon based composites such as biosensors, antibacterial materials, drug delivery, and the diagnosis and treatment of diseases.
MXene is a sort of revolutionary two-dimensional material that possesses distinctive laminated structure and composition of transition metal carbides. It exhibits special physicochemical characteristics including large specific surface area, admirable conductivity, mechanical property and photothermal behaviors, which enable it to represent application value. Furthermore, for pursuing broader application, MXene is usually compounded with carbon-based materials to strengthen comprehensive performances. Therefore, MXene and MXene- carbon based composites has been attracted more attention in various fields such as electronics, biosensors and biomedicine over the past few years. In this review, the fabrication, modification and biomedical applications concerning MXene and MXene-carbon based materials will be introduced. In particular, this review will focus on biomedical applications of MXene and MXene-carbon based composites such as biosensors, antibacterial materials, drug delivery, and the diagnosis and treatment of diseases.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60729-2
摘要:
超薄锂金属（≤50 μm）是下一代高比能锂金属电池负极选择。然而纯锂质软、易脆，其机械加工性较差，导致超薄锂箔的制备工艺复杂、成本高昂；此外相比于较厚的锂金属负极，超薄锂金属负极往往呈现更差的电化学循环性能。本文提出一种“自下而上”的策略制备10-50 μm厚度可控的超薄还原氧化石墨烯/锂金属（rGO/Li）复合箔材，其结构由大量无序随机的rGO片层非平行排列并均匀分散在锂金属内。制备过程中首先将还原氧化石墨烯（rGO）粉片与熔融锂金属在200 °C下搅拌复合，获得微米级的还原氧化石墨烯/锂复合粉片，之后将复合粉片作为原材料进一步通过反复辊压制备出结构均匀、超薄的复合箔材，该方法具有一定的规模化潜力。不同于其他所报道的rGO层状薄膜结构，在复合箔材中rGO片层随机无序分散形成三维网络，有利于实现锂的均匀沉积/剥离。所制备的50 μm超薄无序结构rGO/Li复合箔材负极在对称电池中以1 mA cm−2、1 mAh cm−2条件在醚基电解液中可稳定循环1600小时以上，在与硫化聚丙烯腈（SPAN）正极组配全电池以0.2 C倍率循环220次后比容量高达~675 mAh g−1，优于使用同厚度纯锂负极的电池。
超薄锂金属（≤50 μm）是下一代高比能锂金属电池负极选择。然而纯锂质软、易脆，其机械加工性较差，导致超薄锂箔的制备工艺复杂、成本高昂；此外相比于较厚的锂金属负极，超薄锂金属负极往往呈现更差的电化学循环性能。本文提出一种“自下而上”的策略制备10-50 μm厚度可控的超薄还原氧化石墨烯/锂金属（rGO/Li）复合箔材，其结构由大量无序随机的rGO片层非平行排列并均匀分散在锂金属内。制备过程中首先将还原氧化石墨烯（rGO）粉片与熔融锂金属在200 °C下搅拌复合，获得微米级的还原氧化石墨烯/锂复合粉片，之后将复合粉片作为原材料进一步通过反复辊压制备出结构均匀、超薄的复合箔材，该方法具有一定的规模化潜力。不同于其他所报道的rGO层状薄膜结构，在复合箔材中rGO片层随机无序分散形成三维网络，有利于实现锂的均匀沉积/剥离。所制备的50 μm超薄无序结构rGO/Li复合箔材负极在对称电池中以1 mA cm−2、1 mAh cm−2条件在醚基电解液中可稳定循环1600小时以上，在与硫化聚丙烯腈（SPAN）正极组配全电池以0.2 C倍率循环220次后比容量高达~675 mAh g−1，优于使用同厚度纯锂负极的电池。
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60728-0
摘要:
Carbon fibers (CFs) were surface-modified by a surfactant (ferrocenemethyl)dodecyldimethylammonium bromide (FDDA) for changing the surface properties. Results showed that the FDDA adsorbed onto CFs 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 CFs have little effect on the tensile strength of CFs. Furthermore, 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 CFs exhibited significantly improved interfacial adhesion properties in composites. This method provides a potential approach for preparing recyclable CF/resin composites.
Carbon fibers (CFs) were surface-modified by a surfactant (ferrocenemethyl)dodecyldimethylammonium bromide (FDDA) for changing the surface properties. Results showed that the FDDA adsorbed onto CFs 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 CFs have little effect on the tensile strength of CFs. Furthermore, 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 CFs exhibited significantly improved interfacial adhesion properties in composites. This method provides a potential approach for preparing recyclable CF/resin composites.
, 最新更新时间 , doi: 10.1016/S1872-5805(22)60646-2
摘要:
Interfacial adhesion between carbon fiber (CF) and polyetherketoneketone (PEKK) is a key factor that affects the mechanical performances of their composites. Therefore, it is of great importance to impregnate PEKK into CF bundles as efficiently as possible. Here we report that owing to the high dissolubility, PEKK can be introduced onto CF surfaces via a wet strategy. The excellent wettability of PEKK guarantees a full covering and tight binding on CFs, making it possible to evaluate the interfacial shear strength (IFSS) with the microdroplet method. Furthermore, the interior of CF bundles can be completely and uniformly filled with PEKK by the solution impregnation, leading to a high interlaminar shear strength (ILSS). The maximum IFSS and ILSS can reach 107.8 and 99.3 MPa, respectively. Such superior shear properties are ascribed to the formation of amorphous PEKK confined in the limited spacing between CFs.
Interfacial adhesion between carbon fiber (CF) and polyetherketoneketone (PEKK) is a key factor that affects the mechanical performances of their composites. Therefore, it is of great importance to impregnate PEKK into CF bundles as efficiently as possible. Here we report that owing to the high dissolubility, PEKK can be introduced onto CF surfaces via a wet strategy. The excellent wettability of PEKK guarantees a full covering and tight binding on CFs, making it possible to evaluate the interfacial shear strength (IFSS) with the microdroplet method. Furthermore, the interior of CF bundles can be completely and uniformly filled with PEKK by the solution impregnation, leading to a high interlaminar shear strength (ILSS). The maximum IFSS and ILSS can reach 107.8 and 99.3 MPa, respectively. Such superior shear properties are ascribed to the formation of amorphous PEKK confined in the limited spacing between CFs.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60727-9
摘要:
作为锂离子电池和超级电容器的结合，锂离子电容器由于其兼备电池和电容器的优点而受到了广泛的关注。然而由于其正极双电层电容行为的储能机理，锂离子电容器的能量特性受到了很大的限制。因此，为了从根本上增强锂离子电容器正极材料性能，本研究提出了双离子电容器的储能机理。以柠檬酸钾/镁/铁为原料，合成了兼备石墨质结构与层次化多孔结构的石墨质多孔碳，并以其为正极材料，实现了兼具锂离子电容器正极离子吸附行为与双离子电池正极阴离子插层行为的双离子电容储能机理。由于石墨质多孔碳结构中石墨质结构在高电位下由阴离子插层反应贡献的额外平台容量以及对于材料导电性的增强，石墨质多孔碳正极材料的能量特性远超多孔碳及人造石墨正极，实现了从储能机理的层面的器件性能增强。
作为锂离子电池和超级电容器的结合，锂离子电容器由于其兼备电池和电容器的优点而受到了广泛的关注。然而由于其正极双电层电容行为的储能机理，锂离子电容器的能量特性受到了很大的限制。因此，为了从根本上增强锂离子电容器正极材料性能，本研究提出了双离子电容器的储能机理。以柠檬酸钾/镁/铁为原料，合成了兼备石墨质结构与层次化多孔结构的石墨质多孔碳，并以其为正极材料，实现了兼具锂离子电容器正极离子吸附行为与双离子电池正极阴离子插层行为的双离子电容储能机理。由于石墨质多孔碳结构中石墨质结构在高电位下由阴离子插层反应贡献的额外平台容量以及对于材料导电性的增强，石墨质多孔碳正极材料的能量特性远超多孔碳及人造石墨正极，实现了从储能机理的层面的器件性能增强。
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60726-7
摘要:
In this work, we first designed and fabricated the nanocomposite of zinc sulfide nanodots and 3D N-S co-doped carbon nanosheets (ZnS/NS-CN) successfully derived from waste biomass orange peels using ZnCl2 as hard templates and zinc source, melamine and thiourea as nitrogen and sulfur sources by an elevated temperature sintering and latter etching treatment. When applied to Li-ion batteries, ZnS/NS-CN exhibits high reversible capacity (853.5 mAh g−1 at 0.1 A g−1 after 300 cycles), excellent long-term cycling stability (70.1% capacity retention after 1000 cycles at 5 A g−1) and an outstanding rate capability. Besides, the ZnS/NS-CN//LiNiCoMnO2 full cells assembled and tested at 0.5-4 V exhibited excellent battery performance (140.4 mAh g−1 at 0.2 C after 150 cycles with an energy density of 132.4 Wh kg−1). Such excellent electrochemical performance shows that the anode with reasonable design has a great prospect in lithium-ion batteries (LIBs).
In this work, we first designed and fabricated the nanocomposite of zinc sulfide nanodots and 3D N-S co-doped carbon nanosheets (ZnS/NS-CN) successfully derived from waste biomass orange peels using ZnCl2 as hard templates and zinc source, melamine and thiourea as nitrogen and sulfur sources by an elevated temperature sintering and latter etching treatment. When applied to Li-ion batteries, ZnS/NS-CN exhibits high reversible capacity (853.5 mAh g−1 at 0.1 A g−1 after 300 cycles), excellent long-term cycling stability (70.1% capacity retention after 1000 cycles at 5 A g−1) and an outstanding rate capability. Besides, the ZnS/NS-CN//LiNiCoMnO2 full cells assembled and tested at 0.5-4 V exhibited excellent battery performance (140.4 mAh g−1 at 0.2 C after 150 cycles with an energy density of 132.4 Wh kg−1). Such excellent electrochemical performance shows that the anode with reasonable design has a great prospect in lithium-ion batteries (LIBs).
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60723-1
摘要:
The design of low-cost green catalyst for nitrobenzene (NB) hydrogenation is highly desirable for aniline production. Here, N-doped carbons supported highly-dispersed Co particles were obtained by hydrothermal treatment of glucose, followed by pyrolysis of urea, hydrochar, and cobalt nitrate in one-pot. The effect of pyrolysis temperatures on the structure of catalysts was studied, and the activity was highly affected by the surface areas, Co-loadings and Co-Nx coordination effect in catalysts. Co@NCG-800 as carbonized at 800 °C with 10% Co-species in precursor had extraordinary activity for NB hydrogenation, achieving a full conversion and 99% aniline selectivity in isopropanol under condition of 100 °C and 1 MPa H2 pressure for 2.5 h. NB conversion and aniline selectivity over the catalysts remained almost unchanged even after six recycles, due to strong coordination between N-species and Co-species. The reaction system not only showed superior NB activity but also indicated a green durable catalytic process, facilitating facile operation, easy separation, and catalyst reusability.
The design of low-cost green catalyst for nitrobenzene (NB) hydrogenation is highly desirable for aniline production. Here, N-doped carbons supported highly-dispersed Co particles were obtained by hydrothermal treatment of glucose, followed by pyrolysis of urea, hydrochar, and cobalt nitrate in one-pot. The effect of pyrolysis temperatures on the structure of catalysts was studied, and the activity was highly affected by the surface areas, Co-loadings and Co-Nx coordination effect in catalysts. Co@NCG-800 as carbonized at 800 °C with 10% Co-species in precursor had extraordinary activity for NB hydrogenation, achieving a full conversion and 99% aniline selectivity in isopropanol under condition of 100 °C and 1 MPa H2 pressure for 2.5 h. NB conversion and aniline selectivity over the catalysts remained almost unchanged even after six recycles, due to strong coordination between N-species and Co-species. The reaction system not only showed superior NB activity but also indicated a green durable catalytic process, facilitating facile operation, easy separation, and catalyst reusability.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60720-6
摘要:
The interfacial adhesion between carbon fiber (CF) and matrix is crucial to the performance of CF reinforced polymer composites. To evaluate the contribution of mechanical interlocking and chemical anchoring to the interfacial adhesion properties of CF reinforced epoxy resin (EP) composites, the surface roughness and oxygen-containing functional groups of CFs were decoupled to study their effects on interfacial adhesion. The results show that ammonia treatment enhanced the surface roughness with the elemental composition nearly unchanged, while electrochemical treatment enhanced the chemical properties without changing the surface roughness. The interfacial shear strength (IFSS) of CF/EP was tested by the micro-droplet method, and the function relationship between IFSS and surface roughness as well as oxygen content was obtained by linear fitting. The results show that in the T800SC CFs with bifunctional and tetrafunctional epoxy systems, the contribution coefficient of interface adhesion enhancement by chemical anchoring is higher than that by mechanical interlocking.
The interfacial adhesion between carbon fiber (CF) and matrix is crucial to the performance of CF reinforced polymer composites. To evaluate the contribution of mechanical interlocking and chemical anchoring to the interfacial adhesion properties of CF reinforced epoxy resin (EP) composites, the surface roughness and oxygen-containing functional groups of CFs were decoupled to study their effects on interfacial adhesion. The results show that ammonia treatment enhanced the surface roughness with the elemental composition nearly unchanged, while electrochemical treatment enhanced the chemical properties without changing the surface roughness. The interfacial shear strength (IFSS) of CF/EP was tested by the micro-droplet method, and the function relationship between IFSS and surface roughness as well as oxygen content was obtained by linear fitting. The results show that in the T800SC CFs with bifunctional and tetrafunctional epoxy systems, the contribution coefficient of interface adhesion enhancement by chemical anchoring is higher than that by mechanical interlocking.
Synthesis and electrochemical properties of nano-Si@C nanocomposite anodes for lithium-ion batteries
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60707-3
摘要:
The phenolic resin was coated on the surface of nano-Si by microencapsulation technology, and then carbonized under the Ar protection to prepare nano-Si@C nanocomposite. Firstly, four mass ratios of phenolic resin to nano-Si (1∶2, 1∶4, 1∶6, 1∶8) were employed to prepare nano-Si@C nanocomposites. The obtained average thickness of amorphous carbon coating was 7, 4.5, 3.7, 2.8 nm, respectively. By comparing the cycling and rate capability, the best electrochemical performance was obtained when the mass ratio of phenolic resin to nano Si was 1∶4, that is, the amorphous carbon coating was 4.5 nm.. The electrochemical properties of optimized nano-Si@C nanocomposite was then evaluated comprehensively, which exhibited excellent electrochemical performance as anode material for Li-ion batteries. Under a current density of 100 mAg−1, the nano-Si@C nanocomposite delivered a first discharge specific capacity of 2382 mAhg−1, first charge specific capacity of 1667 mAhg−1, and a first coulombic efficiency of 70%. Moreover, the discharge specific capacity of 835.6 mAhg−1 could be retained after 200 cycles with a high coulombic efficiency of 99.2%. In addition, nano-Si@C nanocomposite also demonstrated superior rate performance. Under the current densities of 100, 200, 500, 1000 and 2000 mAg−1, the average discharge specific capacities were 1716.4, 1231.6, 911.7, 676.1, and 339.8 mAhg−1, respectively. When the current density returned to 100 mAg−1, the specific capacity restored to 1326.4 mAhg−1.
The phenolic resin was coated on the surface of nano-Si by microencapsulation technology, and then carbonized under the Ar protection to prepare nano-Si@C nanocomposite. Firstly, four mass ratios of phenolic resin to nano-Si (1∶2, 1∶4, 1∶6, 1∶8) were employed to prepare nano-Si@C nanocomposites. The obtained average thickness of amorphous carbon coating was 7, 4.5, 3.7, 2.8 nm, respectively. By comparing the cycling and rate capability, the best electrochemical performance was obtained when the mass ratio of phenolic resin to nano Si was 1∶4, that is, the amorphous carbon coating was 4.5 nm.. The electrochemical properties of optimized nano-Si@C nanocomposite was then evaluated comprehensively, which exhibited excellent electrochemical performance as anode material for Li-ion batteries. Under a current density of 100 mAg−1, the nano-Si@C nanocomposite delivered a first discharge specific capacity of 2382 mAhg−1, first charge specific capacity of 1667 mAhg−1, and a first coulombic efficiency of 70%. Moreover, the discharge specific capacity of 835.6 mAhg−1 could be retained after 200 cycles with a high coulombic efficiency of 99.2%. In addition, nano-Si@C nanocomposite also demonstrated superior rate performance. Under the current densities of 100, 200, 500, 1000 and 2000 mAg−1, the average discharge specific capacities were 1716.4, 1231.6, 911.7, 676.1, and 339.8 mAhg−1, respectively. When the current density returned to 100 mAg−1, the specific capacity restored to 1326.4 mAhg−1.
, 最新更新时间 , doi: 10.1016/S1872-5805(23)60706-1
摘要:
The present manuscript reports a coal-based fluorescent CDs which fabricated at room temperature through a friendly method with mixture of hydrogen peroxide (H2O2) and formic acid (HCOOH) as an oxidant instead of concentrated acid (HNO3 or H2SO4). The prepared CDs show the excitation dependent behavior with high QY approximately 7.2%. The as-made CDs are water soluble, robust photo-stability, good resistance to salt solution, insensitive to pH in a range of 2.0-12.0. The coal-based CDs served as a very sensitive nano-probe for the turn-off sensing of Fe3+ ion with a minimum LOD as low as 600 nM in a dynamic range 2 to 100 μM. This efficient, rapid synthesis of coal-based CDs will not only increase high value-added utilization of coal, but also have potential application value in sensing and several another analytical applications.
The present manuscript reports a coal-based fluorescent CDs which fabricated at room temperature through a friendly method with mixture of hydrogen peroxide (H2O2) and formic acid (HCOOH) as an oxidant instead of concentrated acid (HNO3 or H2SO4). The prepared CDs show the excitation dependent behavior with high QY approximately 7.2%. The as-made CDs are water soluble, robust photo-stability, good resistance to salt solution, insensitive to pH in a range of 2.0-12.0. The coal-based CDs served as a very sensitive nano-probe for the turn-off sensing of Fe3+ ion with a minimum LOD as low as 600 nM in a dynamic range 2 to 100 μM. This efficient, rapid synthesis of coal-based CDs will not only increase high value-added utilization of coal, but also have potential application value in sensing and several another analytical applications.
, 最新更新时间 , doi: 10.1016/S1872-5805(22)60643-7
摘要:
Polyether ether ketone (PEEK) has favorable mechanical properties. However, its high melt viscosity limits its applications because it is hard to process. In this study, PEEK nanocomposites modified with carbon nanotubes (CNTs) and polyether imide (PEI) were prepared using a direct wet powder blending method. The melt viscosity of the nanocomposites decreased by approximately 50%. Under optimal conditions, the addition of CNTs and PEI resulted in a synergistic increase in the toughness of the nanocomposites. The elongation at break increased by 129%, and the fracture energy increased by 97%. The uniformly dispersed CNTs/PEI powder reduces the processing difficulty of PEEK nanocomposites without affecting the heat resistance. The nanocomposites prepared by this method have lower melt viscosity. This improvement of the properties of PEEK would facilitate its use in the preparation of thermoplastic composites by powder impregnation or laser sintering technology.
Polyether ether ketone (PEEK) has favorable mechanical properties. However, its high melt viscosity limits its applications because it is hard to process. In this study, PEEK nanocomposites modified with carbon nanotubes (CNTs) and polyether imide (PEI) were prepared using a direct wet powder blending method. The melt viscosity of the nanocomposites decreased by approximately 50%. Under optimal conditions, the addition of CNTs and PEI resulted in a synergistic increase in the toughness of the nanocomposites. The elongation at break increased by 129%, and the fracture energy increased by 97%. The uniformly dispersed CNTs/PEI powder reduces the processing difficulty of PEEK nanocomposites without affecting the heat resistance. The nanocomposites prepared by this method have lower melt viscosity. This improvement of the properties of PEEK would facilitate its use in the preparation of thermoplastic composites by powder impregnation or laser sintering technology.
, 最新更新时间 , doi: 10.1016/S1872-5805(22)60597-3
摘要:
To obtain excellent carbonaceous precursors, the oxidation reaction mechanism and kinetics of ethylene tar were investigated. The oxidation process of ethylene tar was divided into three stages (350-550 K, 550-700 K and 700-900 K) according to the thermogravimetric curve. To reveal the oxidation reaction mechanism of ethylene tar, the components of evolved gases at different stages were further analyzed online by mass spectrometry and infrared technology. Then, based on the thermogravimetric curve of ethylene tar at different reaction temperatures, the whole reaction process was divided into four parts to perform kinetics simulation calculation. With the help of the iso-conversional method (Coats-Redfern) to analyze the linear regression rates (R2) between 17 common reaction kinetics models and experimental data, the optimal reaction kinetics model for expressing oxidation process of ethylene tar was determined. The results show that: (1) In the oxidation process, the side chains of aromatic compounds firstly react with oxygen to form alcohols and aldehydes, leaving peroxy-radicals to aromatic rings. After that, the aromatic compounds with peroxy-radicals undergo polymerization/condensation reaction to form larger molecular. (2) The fourth-order of reaction model is adopted to describe the first three parts of the oxidation process, and the activation energies are 47.330 kJ·mol−1, 18.689 kJ·mol−1 and 9.004 kJ·mol−1 respectively. The three-dimensional diffusion model is applied to the fourth part of the oxidation process, and the activation energy is 88.369 kJ·mol−1.
To obtain excellent carbonaceous precursors, the oxidation reaction mechanism and kinetics of ethylene tar were investigated. The oxidation process of ethylene tar was divided into three stages (350-550 K, 550-700 K and 700-900 K) according to the thermogravimetric curve. To reveal the oxidation reaction mechanism of ethylene tar, the components of evolved gases at different stages were further analyzed online by mass spectrometry and infrared technology. Then, based on the thermogravimetric curve of ethylene tar at different reaction temperatures, the whole reaction process was divided into four parts to perform kinetics simulation calculation. With the help of the iso-conversional method (Coats-Redfern) to analyze the linear regression rates (R2) between 17 common reaction kinetics models and experimental data, the optimal reaction kinetics model for expressing oxidation process of ethylene tar was determined. The results show that: (1) In the oxidation process, the side chains of aromatic compounds firstly react with oxygen to form alcohols and aldehydes, leaving peroxy-radicals to aromatic rings. After that, the aromatic compounds with peroxy-radicals undergo polymerization/condensation reaction to form larger molecular. (2) The fourth-order of reaction model is adopted to describe the first three parts of the oxidation process, and the activation energies are 47.330 kJ·mol−1, 18.689 kJ·mol−1 and 9.004 kJ·mol−1 respectively. The three-dimensional diffusion model is applied to the fourth part of the oxidation process, and the activation energy is 88.369 kJ·mol−1.
, 最新更新时间 , doi: 10.1016/S1872-5805(22)60630-9
摘要:
钠离子电池因资源丰富及成本低等优势，在大规模储能领域备受关注。炭材料作为钠离子电池实用化进程中的关键负极材料，具有高容量、低嵌钠平台、易调控且稳定性好等特点，引起了研究者的广泛关注。掺杂原子可改善炭材料的微观与电子结构，是提升储钠性能的有效途径。常见的杂原子包括N、S、O、P、B等，其中硫原子因其较大的半径能显著扩大层间距、增加缺陷与活性位点，被广泛用于炭负极材料的掺杂改性。本文综述了近年来硫掺杂炭材料的设计制备及在钠离子电池负极中的研究进展，分析了硫掺杂对碳结构的调控机理与改善电池性能的作用机制，最后针对目前面临的挑战和可能的解决方案进行了总结和展望，以期推动硫掺杂炭负极材料在钠离子电池中的实用化进程。
钠离子电池因资源丰富及成本低等优势，在大规模储能领域备受关注。炭材料作为钠离子电池实用化进程中的关键负极材料，具有高容量、低嵌钠平台、易调控且稳定性好等特点，引起了研究者的广泛关注。掺杂原子可改善炭材料的微观与电子结构，是提升储钠性能的有效途径。常见的杂原子包括N、S、O、P、B等，其中硫原子因其较大的半径能显著扩大层间距、增加缺陷与活性位点，被广泛用于炭负极材料的掺杂改性。本文综述了近年来硫掺杂炭材料的设计制备及在钠离子电池负极中的研究进展，分析了硫掺杂对碳结构的调控机理与改善电池性能的作用机制，最后针对目前面临的挑战和可能的解决方案进行了总结和展望，以期推动硫掺杂炭负极材料在钠离子电池中的实用化进程。
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