To fabricate electronic packaging shell of coppermatrix composite with characteristics of high ther mal conductivity and low thermal expansion coefficient, semisolid forming technology, and powder metallurgy was combi...To fabricate electronic packaging shell of coppermatrix composite with characteristics of high ther mal conductivity and low thermal expansion coefficient, semisolid forming technology, and powder metallurgy was combined. Conventional mechanical mixing of Cu and SiC could have insufficient wettability, and a new method of semisolid processing was introduced for billets preparation. The SiC/Cu composites were first prepared by PM, and then, semisolid reheating was performed for the successive semisolid forging. Composite billets with SiC 35 % vol ume fraction were compacted and sintered pressurelessly, microstructure analysis showed that the composites pre pared by PM had high density, and the combination between SiC particles and Cualloy was good. Semisolid reheating was the crucial factor in determining the micro structure and thixotropic property of the billet. An opti mised reheating strategy was proposed: temperature 1,025 ℃and holding time 5 min.展开更多
Silicon/carbon composites,which integrate the high lithium storage performance of silicon with the exceptional mechanical strength and conductivity of carbon,will replace the traditional graphite electrodes for high-e...Silicon/carbon composites,which integrate the high lithium storage performance of silicon with the exceptional mechanical strength and conductivity of carbon,will replace the traditional graphite electrodes for high-energy lithium-ion batteries.Various strategies have been designed to synthesize silicon/carbon composites for tackling the issues of anode pulverization and poor stability in the anodes,thereby improving the lithium storage ability.The effect of the regulation method at each scale on the final negative electrode performance remains unclear.However,it has not been fully clarified how the regulation methods at each scale influence the final anode performance.This review will categorize the materials structure into three scales:molecular scale,nanoscale,and microscale.First,the review will examine modification methods at the molecular scale,focusing on the interfacial bonding force between silicon and carbon.Next,it will summarize various nanostructures and special shapes in the nanoscale to explore the construction of silicon/carbon composites.Lastly,the review will provide an analysis of microscale control approaches,focusing on the formation of composite particle with micron size and the utilization of micro-Si.This review provides a comprehensive overview of the multi-scale design of silicon/carbon composite anode materials and their optimization strategies to enhance the performance of lithium-ion batteries.展开更多
Recent technological advancements,such as portable electronics and electric vehicles,have created a pressing need for more efficient energy storage solutions.Lithium-ion batteries(LIBs)have been the preferred choice f...Recent technological advancements,such as portable electronics and electric vehicles,have created a pressing need for more efficient energy storage solutions.Lithium-ion batteries(LIBs)have been the preferred choice for these applications,with graphite being the standard anode material due to its stability.However,graphite falls short of meeting the growing demand for higher energy density,possessing a theoretical capacity that lags behind.To address this,researchers are actively seeking alternative materials to replace graphite in commercial batteries.One promising avenue involves lithiumalloying materials like silicon and phosphorus,which offer high theoretical capacities.Carbon-silicon composites have emerged as a viable option,showing improved capacity and performance over traditional graphite or pure silicon anodes.Yet,the existing methods for synthesizing these composites remain complex,energy-intensive,and costly,preventing widespread adoption.A groundbreaking approach is presented here:the use of a laser writing strategy to rapidly transform common organic carbon precursors and silicon blends into efficient“graphenic silicon”composite thin films.These films exhibit exceptional structural and energy storage properties.The resulting three-dimensional porous composite anodes showcase impressive attributes,including ultrahigh silicon content,remarkable cyclic stability(over 4500 cycles with∼40%retention),rapid charging rates(up to 10 A g^(-1)),substantial areal capacity(>5.1 mAh cm^(-2)),and excellent gravimetric capacity(>2400 mAh g^(-1) at 0.2 A g^(-1)).This strategy marks a significant step toward the scalable production of high-performance LIB materials.Leveraging widely available,cost-effective precursors,the laser-printed“graphenic silicon”composites demonstrate unparalleled performance,potentially streamlining anode production while maintaining exceptional capabilities.This innovation not only paves the way for advanced LIBs but also sets a precedent for transforming various materials into high-performing electrodes,promising reduced complexity and cost in battery production.展开更多
Silicon(Si)has been studied as a promising alloying type anode for lithium-ion batteries due to its high specific capacity,low operating potential and abundant resources.Nevertheless,huge volume expansion during alloy...Silicon(Si)has been studied as a promising alloying type anode for lithium-ion batteries due to its high specific capacity,low operating potential and abundant resources.Nevertheless,huge volume expansion during alloying/dealloying processes and low electronic conductivity of Si anodes restrict their electrochemical performance.Thus,carbon(C)materials with special physical and chemical properties are applied in Si anodes to effectively solve these problems.This review focuses on current status in the exploration of Si/C anodes,including the lithiation mechanism and solid electrolyte interface formation,various carbon sources in Si/C anodes,such as traditional carbon sources(graphite,pitch,biomass),and novel carbon sources(MXene,graphene,MOFs-derived carbon,graphdiyne,etc.),as well as interfacial bonding modes of Si and C in the Si/C anodes.Finally,we summarize and prospect the selection of carbonaceous materials,structural design and interface control of Si/C anodes,and application of Si/C anodes in all-solid-state lithium-ion batteries and sodium-ion batteries et al.This review will help researchers in the design of novel Si/C anodes for rechargeable batteries.展开更多
Silicon (Si) has been considered as one of the most promising anode material for tHe next generation lithium-ion batteries (LIBs) with high energy densities, due to its high theoretical capacity, abundant availabi...Silicon (Si) has been considered as one of the most promising anode material for tHe next generation lithium-ion batteries (LIBs) with high energy densities, due to its high theoretical capacity, abundant availability and environmental friendliness. However. silicon materials with low intrinsic electric and ionic conductivity suffer from huge volume variation during lithiation/delithiation processes leading to the pulverization of Si and subsequently resulting in severe capacity fading of the electrodes. Coupling of Si with carbon (C) realizes a favorable combination of the two materials properties, such as high lithiation capacity of Si and excellent mechanical and conductive properties of C. making silicon/carbon composite (Si/C) ideal candidates for LIBs anodes. In this review, recent progresses of Si/C materials utilized in LIBs are summarized in terms of structural design principles, material synthesis methods, morphological characteristics and electrochemical performances by highlighting the material structures. The mechanisms behind the performance enhancement are also discussed. Moreover, other factors that affect the performance of Si/C anodes, such as prelithiation, electrolyte additives, and binders, are also discussed. We aim to present a full scope of the Si/C-based anodes, and help understand and design future structures of Si/C anodes in LIBs,展开更多
A supercell of a nanotube heterojunction formed by an (8, 0) carbon nanotube (CNT) and an (8, 0) silicon carbide nanotube (SiCNT) is established, in which 96 C atoms and 32 Si atoms are included. The geometry ...A supercell of a nanotube heterojunction formed by an (8, 0) carbon nanotube (CNT) and an (8, 0) silicon carbide nanotube (SiCNT) is established, in which 96 C atoms and 32 Si atoms are included. The geometry optimization and the electronic property of the heterojunction are implemented through the first-principles calculation based on the density functional theory (DFT). The results indicate that the structural rearrangement takes place mainly on the interface and the energy gap of the heterojunction is 0.31 eV, which is narrower than those of the isolated CNT and the isolated SiCNT. By using the average bond energy method, the valence band offset and the conduction band offset are obtained as 0.71 and -0.03 eV, respectively.展开更多
The effects of reaction time,reaction temperature,stirring speed and flowrate of CO2 gas on desilication rate and loss rate of vanadium were studied.The results indicated that desilication rate increases with the incr...The effects of reaction time,reaction temperature,stirring speed and flowrate of CO2 gas on desilication rate and loss rate of vanadium were studied.The results indicated that desilication rate increases with the increase of flowrate of CO2 gas and reaction time.Reaction temperature and stirring speed have little effect on desilication rate,while influence the loss rate of vanadium significantly.Under the condition of reaction time of 2 h,reaction temperature of 95℃,stirring speed of 180 r/min,flowrate of CO2 gas of 60 mL/min and aging time of 2 h,desilication rate is more than 96%and the loss rate of vanadium is about 4.24%.The residue of desilication process can be processed for silicon materials,such as high-grade hydrated silica,which commonly known as white carbon black.In addition,with this carbonation method,leaching regents NaOH can be recycled by simple treatments.展开更多
Various of modifiers were used to modify the surface activity of white carbon black. The oil absorption, viscosity, hydrophobic rate and burning loss of white carbon black and the mechanical propertiess of silicone ru...Various of modifiers were used to modify the surface activity of white carbon black. The oil absorption, viscosity, hydrophobic rate and burning loss of white carbon black and the mechanical propertiess of silicone rubber were measured. The influences of the modifiers on the properties of white carbon black and the mechanical properties of silicone rubber were discussed.展开更多
Crop harvesting and residue removal from croplands often result in imbalanced biogeochemical cycles of carbon and nutrients in croplands, putting forward an austere challenge to sustainable agricultural production. As...Crop harvesting and residue removal from croplands often result in imbalanced biogeochemical cycles of carbon and nutrients in croplands, putting forward an austere challenge to sustainable agricultural production. As a beneficial element, silicon(Si) has multiple eco-physiological functions, which could help crops to acclimatize their unfavorable habitats. Although many studies have reported that the application of Si can alleviate multiple abiotic and biotic stresses and increase biomass accumulation, the effects of Si on carbon immobilization and nutrients uptake into plants in croplands have not yet been explored. This review focused on Si-associated regulation of plant carbon accumulation, lignin biosynthesis, and nutrients uptake, which are important for biogeochemical cycles of carbon and nutrients in croplands. The tradeoff analysis indicates that the supply of bioavailable Si can enhance plant net photosynthetic rate and biomass carbon production(especially root biomass input to soil organic carbon pool), but reduce shoot lignin biosynthesis. Besides, the application of Si could improve uptake of most nutrients under deficient conditions, but restricts excess uptake when they are supplied in surplus amounts. Nevertheless, Si application to crops may enhance the uptake of nitrogen and iron when they are supplied in deficient to luxurious amounts, while potassium uptake enhanced by Si application is often involved in alleviating salt stress and inhibiting excess sodium uptake in plants. More importantly, the amount of Si accumulated in plant positively correlates with nutrients release during the decay of crop biomass, but negatively correlates with straw decomposability due to the reduced lignin synthesis. The Si-mediated plant growth and litter decomposition collectively suggest that Si cycling in croplands plays important roles in biogeochemical cycles of carbon and nutrients. Hence, scientific Si management in croplands will be helpful for maintaining sustainable development of agriculture.展开更多
Microclusters from different structures of silicon and carbon are studied by SIMS under UHV conditions in the mass range below M=200. The sputtered mass spectra of ions Sin+, Cn+ and Cn were obtained from the 10 keV O...Microclusters from different structures of silicon and carbon are studied by SIMS under UHV conditions in the mass range below M=200. The sputtered mass spectra of ions Sin+, Cn+ and Cn were obtained from the 10 keV O2+ primary beam bombardment. Comparisons of each spectrum in each group have shown the strong structure effects on the cluster patterns. A brief discussion on the results has been given.展开更多
Anovel silicon containing carbon precursor was synthesised by reacting a petroleum pitchfraction and polydimethylsilane. The precursor containing about 26wt% Si was meltspunintofibresand then oxidativelystabilised in...Anovel silicon containing carbon precursor was synthesised by reacting a petroleum pitchfraction and polydimethylsilane. The precursor containing about 26wt% Si was meltspunintofibresand then oxidativelystabilised in airto renderthefibresinfusiblebefore pyrolysisat1200℃underinertatmospheretoproduceC Sialloy( CSA) fibres. Theextentofstabili sation wasfoundto becriticalto the development of mechanicalstrength of thefibres which varied with heattreatmenttemperature, showing a maximum at 1200 ℃when thestrength was 1 4 1 6 GPa. Thesestrengthsareremarkably goodconsideringthelow modulus whichis duetothe quite high failurestrains. Thefibrescanshow excellentresistanceto oxidation if given an initialshortexposureto oxygen athigh temperature duetotheformation of an im perceptiblelayer of silica. CSAfibreshavethe advantagesof both carbon fibresand SiCfi bres,thusextended application areascan beenvisaged .展开更多
Carbon nanotube (CNT) filled silicone rubber (SR) composites were synthesized by in situ polymerization.The effect of strain on the electrical resistance of the CNT/SR composites and the structure evolution of CNT...Carbon nanotube (CNT) filled silicone rubber (SR) composites were synthesized by in situ polymerization.The effect of strain on the electrical resistance of the CNT/SR composites and the structure evolution of CNT networks during tensile deformation were investigated.The results showed that the CNT/SR composites had high sensitivity of resistance-strain response.In a wide strain range (0-125%),the change of resistivity could reach 107,which was closely associated with the evolution process of the conductive CNT-network structure.The volume expansion of the composites in the tensile process led to a gradual decrease in the volume fraction of CNTs with the strain increase.When CNT loading was lower than the percolation threshold,CNT network was in disconnected state with a rapid increase in electrical resistance of the composites.Furthermore,the CNT loading had remarkable effect on the sensitivity of resistance-strain response in the composites.展开更多
This paper describes a new method to create nanoscale SiO2 pits or channels using single-walled carbon nanotubes (SWNTs) in an HF solution at room temperature within a few seconds. Using aligned SWNT arrays, a patte...This paper describes a new method to create nanoscale SiO2 pits or channels using single-walled carbon nanotubes (SWNTs) in an HF solution at room temperature within a few seconds. Using aligned SWNT arrays, a pattern of nanoscale SiO2 channels can be prepared. The nanoscale SiO2 patterns can also be created on the surface of three- dimensional (3D) SiO2 substrate and even the nanoscale trenches can be constructed with arbitrary shapes. A possible mechanism for this enhanced etching of SiO2 has been qualitatively analysed using defects in SWNTs, combined with H3O+ electric double layers around SWNTs in an HF solution.展开更多
Ten studied steels including different carbon content, silicon content, and manganese content were deformed in compression over a temperature range of 600 ?C to 1 000 ?C at the strain rate of 1 s-1. The curves of the ...Ten studied steels including different carbon content, silicon content, and manganese content were deformed in compression over a temperature range of 600 ?C to 1 000 ?C at the strain rate of 1 s-1. The curves of the mean flow stressdeformation temperature were drawn up. The mean flow stresses of higher carbon content steels decreased continuously as the applied deformation temperature increased in the whole temperature range, while the mean flow stress of lowest carbon steel displayed an abrupt drop near the two phases region. The reason for the abrupt drop phenomena was explained as the result of phase transformation. The mean flow stresses of steels with high silicon content and low manganese content also have this phenomena.展开更多
We previously reported the direct electrochemical detection of insulin at bare carbon electrodes. Here a novel modified acetylene carbon black paste electrode(SiC/CB-CPE), based on the outstanding characteristics of s...We previously reported the direct electrochemical detection of insulin at bare carbon electrodes. Here a novel modified acetylene carbon black paste electrode(SiC/CB-CPE), based on the outstanding characteristics of silicon carbide nanostructure,was developed for the electrooxidation of insulin in alkaline solution and it was characterized by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) in 5 mmol/L Fe(CN)63-/4- solution. It is found that silicon carbide nanostructure doped into the CB-CPE greatly facilitates the redox electrochemistry of Fe(CN)63-/4- probe and the electrochemical oxidation of insulin. The electrooxidation of insulin is a one-electron and one-proton reaction and an irreversible adsorption-controlled electrode process. The anodic oxidation current increases linearly with the concentration of insulin from 1×10-7mol/L to1.2×10-6mol/L in 0.1 mol/L Na2CO3-NaHCO3 buffer solution(pH 10.0) and the detection limit was 50 nmol/L. In addition, the SiC/CB-CPE shows good sensitivity, reproducibility, renewability and capacity of resisting disturbance.展开更多
To increase the capacity of the negative electrode for lithium-ion secondary batteries, we prepared Si-containing carbon microspheres. The target compound was obtained by thermal decomposition of hexaphenyldisilane em...To increase the capacity of the negative electrode for lithium-ion secondary batteries, we prepared Si-containing carbon microspheres. The target compound was obtained by thermal decomposition of hexaphenyldisilane embedded in porous carbon particles that contained Si-nanoparticles characterized by various methods. When charging/discharging characteristics were evaluated using a cell having the obtained material as a negative electrode, a remarkable improvement in charging characteristics was observed.展开更多
Silicon (Si) is regarded as a promising material for lithium-ion battery anode because of high theoretical capacity. Nevertheless, Si faces particle pulverization and rapid capacity fading due to serious volume change...Silicon (Si) is regarded as a promising material for lithium-ion battery anode because of high theoretical capacity. Nevertheless, Si faces particle pulverization and rapid capacity fading due to serious volume change during the lithiation and the delithiation process. In this work, a silicon/carbon composite constituted to Si powder and carbon nanofiber (CNF) is produced to solve the above issues as a new design structure of anode material. The Si powder was recycled from the silicon slicing waste in photovoltaic industry and the CNF was from dry rice straws. By mixing the purified Si powder with CNF, the composite was synthesized by the freeze-drying method and calcination. In the cyclic test, Si adding with 1 wt% CNF showed 3091 mAh/g capacity in the first cycle and 1079 mAh/g capacity after 100 cycles at the current density of 0.5 A/g, which were both better than pristine Si. SEM images also show the composite structure can eliminate cracks on the surface of the electrode during cycling. CNF attaching on Si particles can increase specific surface area, so binder can easily combine the active materials and the conductive materials together. This strategy enhances the structure stability and prevents the electrode from delamination.展开更多
Plasma immersion ion implantation and deposition (PIII&D) has been shown to be an effective tech- nique to enhance the surface bioactivity of materials. In this paper, recent progress made in our laboratory on pla...Plasma immersion ion implantation and deposition (PIII&D) has been shown to be an effective tech- nique to enhance the surface bioactivity of materials. In this paper, recent progress made in our laboratory on plasma surface modification single-crystal silicon and amorphous carbon is reviewed. Silicon is the most important material in the integrated circuit industry but its surface biocompatibility has not been investigated in details. We have re- cently performed hydrogen PIII into silicon and observed the biomimetic growth of apatite on its surface in simulated body fluid. Diamond-like carbon (DLC) is widely used in the industry due to its excellent mechanical properties and chemical inertness. The use of this material in biomedical engineering has also attracted much attention. It has been observed in our laboratory that doping DLC with nitrogen by means of PIII can improve the surface blood compati- bility. The properties as well as in vitro biological test results will be discussed in this article.展开更多
本文以管状和盘状两种天然硅藻土作为初始原料,制备了一系列硅藻土衍生硅碳负极材料,并采用X射线衍射仪(XRD)、拉曼光谱(Raman)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X-射线光电子能谱(XPS)等测试手段系统表征了所制备样品的晶...本文以管状和盘状两种天然硅藻土作为初始原料,制备了一系列硅藻土衍生硅碳负极材料,并采用X射线衍射仪(XRD)、拉曼光谱(Raman)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X-射线光电子能谱(XPS)等测试手段系统表征了所制备样品的晶体结构、微观形貌及化学组成.将制备的硅藻土衍生硅碳负极材料作为活性物质组装为锂离子电池,对比了管状和盘状两种形貌对其储锂性能的影响,并详细考察了沥青衍生碳包覆层的加入量对硅碳负极材料比容量及循环稳定性的影响.测试结果表明,样品管DE-1∶3和管DE-1∶6在0.2 A g^(-1)较低电流密度下均具有较好的容量保持率,循环500次之后比容量分别可保持443 mAh g^(-1)和414 mAh g^(-1),而样品管DE-1∶6则在0.5 A g^(-1)较大电流密度下具有更好的结构稳定性.展开更多
基金supported by the National Natural Science Foundation of China(No.51174028)the Beijing Natural Science Foundation(No.2102029)
文摘To fabricate electronic packaging shell of coppermatrix composite with characteristics of high ther mal conductivity and low thermal expansion coefficient, semisolid forming technology, and powder metallurgy was combined. Conventional mechanical mixing of Cu and SiC could have insufficient wettability, and a new method of semisolid processing was introduced for billets preparation. The SiC/Cu composites were first prepared by PM, and then, semisolid reheating was performed for the successive semisolid forging. Composite billets with SiC 35 % vol ume fraction were compacted and sintered pressurelessly, microstructure analysis showed that the composites pre pared by PM had high density, and the combination between SiC particles and Cualloy was good. Semisolid reheating was the crucial factor in determining the micro structure and thixotropic property of the billet. An opti mised reheating strategy was proposed: temperature 1,025 ℃and holding time 5 min.
基金funded by the Research Fund of State Key Laboratory of Mesoscience and Engineering (MESO-23-T03)the National Natural Science Foundation (22278423)+1 种基金the National Key Research and Development Program of China (2022YFB3805602)the Science Foundation of China University of Petroleum,Beijing (2462021QNXZ007)。
文摘Silicon/carbon composites,which integrate the high lithium storage performance of silicon with the exceptional mechanical strength and conductivity of carbon,will replace the traditional graphite electrodes for high-energy lithium-ion batteries.Various strategies have been designed to synthesize silicon/carbon composites for tackling the issues of anode pulverization and poor stability in the anodes,thereby improving the lithium storage ability.The effect of the regulation method at each scale on the final negative electrode performance remains unclear.However,it has not been fully clarified how the regulation methods at each scale influence the final anode performance.This review will categorize the materials structure into three scales:molecular scale,nanoscale,and microscale.First,the review will examine modification methods at the molecular scale,focusing on the interfacial bonding force between silicon and carbon.Next,it will summarize various nanostructures and special shapes in the nanoscale to explore the construction of silicon/carbon composites.Lastly,the review will provide an analysis of microscale control approaches,focusing on the formation of composite particle with micron size and the utilization of micro-Si.This review provides a comprehensive overview of the multi-scale design of silicon/carbon composite anode materials and their optimization strategies to enhance the performance of lithium-ion batteries.
文摘Recent technological advancements,such as portable electronics and electric vehicles,have created a pressing need for more efficient energy storage solutions.Lithium-ion batteries(LIBs)have been the preferred choice for these applications,with graphite being the standard anode material due to its stability.However,graphite falls short of meeting the growing demand for higher energy density,possessing a theoretical capacity that lags behind.To address this,researchers are actively seeking alternative materials to replace graphite in commercial batteries.One promising avenue involves lithiumalloying materials like silicon and phosphorus,which offer high theoretical capacities.Carbon-silicon composites have emerged as a viable option,showing improved capacity and performance over traditional graphite or pure silicon anodes.Yet,the existing methods for synthesizing these composites remain complex,energy-intensive,and costly,preventing widespread adoption.A groundbreaking approach is presented here:the use of a laser writing strategy to rapidly transform common organic carbon precursors and silicon blends into efficient“graphenic silicon”composite thin films.These films exhibit exceptional structural and energy storage properties.The resulting three-dimensional porous composite anodes showcase impressive attributes,including ultrahigh silicon content,remarkable cyclic stability(over 4500 cycles with∼40%retention),rapid charging rates(up to 10 A g^(-1)),substantial areal capacity(>5.1 mAh cm^(-2)),and excellent gravimetric capacity(>2400 mAh g^(-1) at 0.2 A g^(-1)).This strategy marks a significant step toward the scalable production of high-performance LIB materials.Leveraging widely available,cost-effective precursors,the laser-printed“graphenic silicon”composites demonstrate unparalleled performance,potentially streamlining anode production while maintaining exceptional capabilities.This innovation not only paves the way for advanced LIBs but also sets a precedent for transforming various materials into high-performing electrodes,promising reduced complexity and cost in battery production.
基金supported by the National Natural Science Foundation of China(5197219862133007)the Taishan Scholars Program of Shandong Province(tsqn201812002,ts20190908)+1 种基金the Shenzhen Fundamental Research Program(JCYJ20190807093405503)The Natural Science Foundation of Shandong Province(No.ZR2020JQ19)。
文摘Silicon(Si)has been studied as a promising alloying type anode for lithium-ion batteries due to its high specific capacity,low operating potential and abundant resources.Nevertheless,huge volume expansion during alloying/dealloying processes and low electronic conductivity of Si anodes restrict their electrochemical performance.Thus,carbon(C)materials with special physical and chemical properties are applied in Si anodes to effectively solve these problems.This review focuses on current status in the exploration of Si/C anodes,including the lithiation mechanism and solid electrolyte interface formation,various carbon sources in Si/C anodes,such as traditional carbon sources(graphite,pitch,biomass),and novel carbon sources(MXene,graphene,MOFs-derived carbon,graphdiyne,etc.),as well as interfacial bonding modes of Si and C in the Si/C anodes.Finally,we summarize and prospect the selection of carbonaceous materials,structural design and interface control of Si/C anodes,and application of Si/C anodes in all-solid-state lithium-ion batteries and sodium-ion batteries et al.This review will help researchers in the design of novel Si/C anodes for rechargeable batteries.
文摘Silicon (Si) has been considered as one of the most promising anode material for tHe next generation lithium-ion batteries (LIBs) with high energy densities, due to its high theoretical capacity, abundant availability and environmental friendliness. However. silicon materials with low intrinsic electric and ionic conductivity suffer from huge volume variation during lithiation/delithiation processes leading to the pulverization of Si and subsequently resulting in severe capacity fading of the electrodes. Coupling of Si with carbon (C) realizes a favorable combination of the two materials properties, such as high lithiation capacity of Si and excellent mechanical and conductive properties of C. making silicon/carbon composite (Si/C) ideal candidates for LIBs anodes. In this review, recent progresses of Si/C materials utilized in LIBs are summarized in terms of structural design principles, material synthesis methods, morphological characteristics and electrochemical performances by highlighting the material structures. The mechanisms behind the performance enhancement are also discussed. Moreover, other factors that affect the performance of Si/C anodes, such as prelithiation, electrolyte additives, and binders, are also discussed. We aim to present a full scope of the Si/C-based anodes, and help understand and design future structures of Si/C anodes in LIBs,
基金supported by the National Defense Pre-research Foundation of China (Grant No 9140A08060407DZ0103)
文摘A supercell of a nanotube heterojunction formed by an (8, 0) carbon nanotube (CNT) and an (8, 0) silicon carbide nanotube (SiCNT) is established, in which 96 C atoms and 32 Si atoms are included. The geometry optimization and the electronic property of the heterojunction are implemented through the first-principles calculation based on the density functional theory (DFT). The results indicate that the structural rearrangement takes place mainly on the interface and the energy gap of the heterojunction is 0.31 eV, which is narrower than those of the isolated CNT and the isolated SiCNT. By using the average bond energy method, the valence band offset and the conduction band offset are obtained as 0.71 and -0.03 eV, respectively.
基金Project(50974133)supported by the National Natural Science Foundation of China
文摘The effects of reaction time,reaction temperature,stirring speed and flowrate of CO2 gas on desilication rate and loss rate of vanadium were studied.The results indicated that desilication rate increases with the increase of flowrate of CO2 gas and reaction time.Reaction temperature and stirring speed have little effect on desilication rate,while influence the loss rate of vanadium significantly.Under the condition of reaction time of 2 h,reaction temperature of 95℃,stirring speed of 180 r/min,flowrate of CO2 gas of 60 mL/min and aging time of 2 h,desilication rate is more than 96%and the loss rate of vanadium is about 4.24%.The residue of desilication process can be processed for silicon materials,such as high-grade hydrated silica,which commonly known as white carbon black.In addition,with this carbonation method,leaching regents NaOH can be recycled by simple treatments.
文摘Various of modifiers were used to modify the surface activity of white carbon black. The oil absorption, viscosity, hydrophobic rate and burning loss of white carbon black and the mechanical propertiess of silicone rubber were measured. The influences of the modifiers on the properties of white carbon black and the mechanical properties of silicone rubber were discussed.
基金supports from the National Natural Science Foundation of China (41522207, 41571130042, 31572191 and 31772387)the National Key R&D Program of China (2016YFA0601002)
文摘Crop harvesting and residue removal from croplands often result in imbalanced biogeochemical cycles of carbon and nutrients in croplands, putting forward an austere challenge to sustainable agricultural production. As a beneficial element, silicon(Si) has multiple eco-physiological functions, which could help crops to acclimatize their unfavorable habitats. Although many studies have reported that the application of Si can alleviate multiple abiotic and biotic stresses and increase biomass accumulation, the effects of Si on carbon immobilization and nutrients uptake into plants in croplands have not yet been explored. This review focused on Si-associated regulation of plant carbon accumulation, lignin biosynthesis, and nutrients uptake, which are important for biogeochemical cycles of carbon and nutrients in croplands. The tradeoff analysis indicates that the supply of bioavailable Si can enhance plant net photosynthetic rate and biomass carbon production(especially root biomass input to soil organic carbon pool), but reduce shoot lignin biosynthesis. Besides, the application of Si could improve uptake of most nutrients under deficient conditions, but restricts excess uptake when they are supplied in surplus amounts. Nevertheless, Si application to crops may enhance the uptake of nitrogen and iron when they are supplied in deficient to luxurious amounts, while potassium uptake enhanced by Si application is often involved in alleviating salt stress and inhibiting excess sodium uptake in plants. More importantly, the amount of Si accumulated in plant positively correlates with nutrients release during the decay of crop biomass, but negatively correlates with straw decomposability due to the reduced lignin synthesis. The Si-mediated plant growth and litter decomposition collectively suggest that Si cycling in croplands plays important roles in biogeochemical cycles of carbon and nutrients. Hence, scientific Si management in croplands will be helpful for maintaining sustainable development of agriculture.
文摘Microclusters from different structures of silicon and carbon are studied by SIMS under UHV conditions in the mass range below M=200. The sputtered mass spectra of ions Sin+, Cn+ and Cn were obtained from the 10 keV O2+ primary beam bombardment. Comparisons of each spectrum in each group have shown the strong structure effects on the cluster patterns. A brief discussion on the results has been given.
文摘Anovel silicon containing carbon precursor was synthesised by reacting a petroleum pitchfraction and polydimethylsilane. The precursor containing about 26wt% Si was meltspunintofibresand then oxidativelystabilised in airto renderthefibresinfusiblebefore pyrolysisat1200℃underinertatmospheretoproduceC Sialloy( CSA) fibres. Theextentofstabili sation wasfoundto becriticalto the development of mechanicalstrength of thefibres which varied with heattreatmenttemperature, showing a maximum at 1200 ℃when thestrength was 1 4 1 6 GPa. Thesestrengthsareremarkably goodconsideringthelow modulus whichis duetothe quite high failurestrains. Thefibrescanshow excellentresistanceto oxidation if given an initialshortexposureto oxygen athigh temperature duetotheformation of an im perceptiblelayer of silica. CSAfibreshavethe advantagesof both carbon fibresand SiCfi bres,thusextended application areascan beenvisaged .
基金Funded by Liaoning Education Department (No.LS2010128)the Scientific Research Fund of University of Jinan (No.XKY0901)
文摘Carbon nanotube (CNT) filled silicone rubber (SR) composites were synthesized by in situ polymerization.The effect of strain on the electrical resistance of the CNT/SR composites and the structure evolution of CNT networks during tensile deformation were investigated.The results showed that the CNT/SR composites had high sensitivity of resistance-strain response.In a wide strain range (0-125%),the change of resistivity could reach 107,which was closely associated with the evolution process of the conductive CNT-network structure.The volume expansion of the composites in the tensile process led to a gradual decrease in the volume fraction of CNTs with the strain increase.When CNT loading was lower than the percolation threshold,CNT network was in disconnected state with a rapid increase in electrical resistance of the composites.Furthermore,the CNT loading had remarkable effect on the sensitivity of resistance-strain response in the composites.
基金supported by the National Natural Science Foundation of China (Grant Nos. 90406007, 61076069, 60776053, and 10434010)the National Basic Research Program of China (Grant No. 2007CB936800)
文摘This paper describes a new method to create nanoscale SiO2 pits or channels using single-walled carbon nanotubes (SWNTs) in an HF solution at room temperature within a few seconds. Using aligned SWNT arrays, a pattern of nanoscale SiO2 channels can be prepared. The nanoscale SiO2 patterns can also be created on the surface of three- dimensional (3D) SiO2 substrate and even the nanoscale trenches can be constructed with arbitrary shapes. A possible mechanism for this enhanced etching of SiO2 has been qualitatively analysed using defects in SWNTs, combined with H3O+ electric double layers around SWNTs in an HF solution.
基金Funded by Shanghai Pujiang Program(No.16PJ1430200)
文摘Ten studied steels including different carbon content, silicon content, and manganese content were deformed in compression over a temperature range of 600 ?C to 1 000 ?C at the strain rate of 1 s-1. The curves of the mean flow stressdeformation temperature were drawn up. The mean flow stresses of higher carbon content steels decreased continuously as the applied deformation temperature increased in the whole temperature range, while the mean flow stress of lowest carbon steel displayed an abrupt drop near the two phases region. The reason for the abrupt drop phenomena was explained as the result of phase transformation. The mean flow stresses of steels with high silicon content and low manganese content also have this phenomena.
基金Funded by the Innovative Talent Training Project of Chongqing University(CDJXS11220004)the Fundamental Research Funds for the Central Universities of Chongqing University+1 种基金the Natural Science Foundation Project of CQ CSTC(No.2011BB5134)the National Natural Science Foundation of China(No.NSFC81101417)
文摘We previously reported the direct electrochemical detection of insulin at bare carbon electrodes. Here a novel modified acetylene carbon black paste electrode(SiC/CB-CPE), based on the outstanding characteristics of silicon carbide nanostructure,was developed for the electrooxidation of insulin in alkaline solution and it was characterized by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) in 5 mmol/L Fe(CN)63-/4- solution. It is found that silicon carbide nanostructure doped into the CB-CPE greatly facilitates the redox electrochemistry of Fe(CN)63-/4- probe and the electrochemical oxidation of insulin. The electrooxidation of insulin is a one-electron and one-proton reaction and an irreversible adsorption-controlled electrode process. The anodic oxidation current increases linearly with the concentration of insulin from 1×10-7mol/L to1.2×10-6mol/L in 0.1 mol/L Na2CO3-NaHCO3 buffer solution(pH 10.0) and the detection limit was 50 nmol/L. In addition, the SiC/CB-CPE shows good sensitivity, reproducibility, renewability and capacity of resisting disturbance.
文摘To increase the capacity of the negative electrode for lithium-ion secondary batteries, we prepared Si-containing carbon microspheres. The target compound was obtained by thermal decomposition of hexaphenyldisilane embedded in porous carbon particles that contained Si-nanoparticles characterized by various methods. When charging/discharging characteristics were evaluated using a cell having the obtained material as a negative electrode, a remarkable improvement in charging characteristics was observed.
文摘Silicon (Si) is regarded as a promising material for lithium-ion battery anode because of high theoretical capacity. Nevertheless, Si faces particle pulverization and rapid capacity fading due to serious volume change during the lithiation and the delithiation process. In this work, a silicon/carbon composite constituted to Si powder and carbon nanofiber (CNF) is produced to solve the above issues as a new design structure of anode material. The Si powder was recycled from the silicon slicing waste in photovoltaic industry and the CNF was from dry rice straws. By mixing the purified Si powder with CNF, the composite was synthesized by the freeze-drying method and calcination. In the cyclic test, Si adding with 1 wt% CNF showed 3091 mAh/g capacity in the first cycle and 1079 mAh/g capacity after 100 cycles at the current density of 0.5 A/g, which were both better than pristine Si. SEM images also show the composite structure can eliminate cracks on the surface of the electrode during cycling. CNF attaching on Si particles can increase specific surface area, so binder can easily combine the active materials and the conductive materials together. This strategy enhances the structure stability and prevents the electrode from delamination.
基金Jointly supported by Hong Kong Research Grants Council (RGC) Competitive Earmarked Research Grant (CERG) #City U1137/03E Germany / Hong Kong Joint Research Scheme sponsored by the Research Grants Council of Hong Kong and the German Academic Ex
文摘Plasma immersion ion implantation and deposition (PIII&D) has been shown to be an effective tech- nique to enhance the surface bioactivity of materials. In this paper, recent progress made in our laboratory on plasma surface modification single-crystal silicon and amorphous carbon is reviewed. Silicon is the most important material in the integrated circuit industry but its surface biocompatibility has not been investigated in details. We have re- cently performed hydrogen PIII into silicon and observed the biomimetic growth of apatite on its surface in simulated body fluid. Diamond-like carbon (DLC) is widely used in the industry due to its excellent mechanical properties and chemical inertness. The use of this material in biomedical engineering has also attracted much attention. It has been observed in our laboratory that doping DLC with nitrogen by means of PIII can improve the surface blood compati- bility. The properties as well as in vitro biological test results will be discussed in this article.
文摘本文以管状和盘状两种天然硅藻土作为初始原料,制备了一系列硅藻土衍生硅碳负极材料,并采用X射线衍射仪(XRD)、拉曼光谱(Raman)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X-射线光电子能谱(XPS)等测试手段系统表征了所制备样品的晶体结构、微观形貌及化学组成.将制备的硅藻土衍生硅碳负极材料作为活性物质组装为锂离子电池,对比了管状和盘状两种形貌对其储锂性能的影响,并详细考察了沥青衍生碳包覆层的加入量对硅碳负极材料比容量及循环稳定性的影响.测试结果表明,样品管DE-1∶3和管DE-1∶6在0.2 A g^(-1)较低电流密度下均具有较好的容量保持率,循环500次之后比容量分别可保持443 mAh g^(-1)和414 mAh g^(-1),而样品管DE-1∶6则在0.5 A g^(-1)较大电流密度下具有更好的结构稳定性.