As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation ...As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation and fragmentation.This ultimately leads to a decrease in cell capacity.The trends of volume expansion and capacity change of the SiO/graphite(SiO/C)composite electrode during cycling were investigated via in situ expansion monitoring.First,a series of expansion test schemes were designed,and the linear relationship between negative electrode expansion and cell capacity degradation was quantitatively analyzed.Then,the effects of different initial pressures on the long-term cycling performance of the cell were evaluated.Finally,the mechanism of their effects was analyzed by scanning electron microscope.The results show that after 50 cycles,the cell capacity decreases from 2.556 mAh to 1.689 mAh,with a capacity retention ratio(CRR)of only 66.08%.A linear relationship between the capacity retention ratio and thickness expansion was found.Electrochemical measurements and scanning electron microscope images demonstrate that intense stress inhibits the lithiation of the negative electrode and that the electrode is more susceptible to irreversible damage during cycling.Overall,these results reveal the relationship between the cycling performance of SiO and the internal pressure of the electrode from a macroscopic point of view,which provides some reference for the application of SiO/C composite electrodes in lithium-ion batteries.展开更多
The silicon-graphite(Si-C)composite electrode is considered a promising candidate for next-generation commercial electrodes due to its high capacity.However,lithium-ion batteries with silicon electrodes often experien...The silicon-graphite(Si-C)composite electrode is considered a promising candidate for next-generation commercial electrodes due to its high capacity.However,lithium-ion batteries with silicon electrodes often experience capacity fading and poor cyclic performance,primarily due to the mechanical degradation of the solid-electrolyte interphase(SEI).In this work,we present a homogenized constitutive model for Si-C composite electrodes under finite deformation,incorporating lithium-ion concentration-dependent properties.We perform a wrinkling analysis and systematically examine the influence of key parameters,such as modulus and thickness ratios,on the critical conditions for instability.Additionally,we investigate the ratcheting effect across varying silicon contents.Our findings reveal that maintaining the silicon content within an optimal range effectively reduces plastic accumulation during charge–discharge cycles.These insights provide crucial guidance for optimizing the design and fabrication of Si–C electrode systems,enhancing their durability and performance.展开更多
The recently reported silicon/graphite(Si/Gr)composite electrode with a layered structure is a promising approach to achieve high capacity and stable cycling of Si-based electrodes in lithium-ion batteries.However,the...The recently reported silicon/graphite(Si/Gr)composite electrode with a layered structure is a promising approach to achieve high capacity and stable cycling of Si-based electrodes in lithium-ion batteries.However,there is still a need to clarify why particular layered structures are effective and why others are ineffective or even detrimental.In this work,an unreported mechanism dominated by the porosity evolution of electrodes is proposed for the degradation behavior of layered Si/Gr electrodes.First,the effect of layering sequence on the overall electrode performance is investigated experimentally,and the results suggest that the cycling performance of the silicon-on-graphite(SG)electrode is much superior to that of the graphite-on-silicon electrode.To explain this phenomenon,a coupled mechanical-electrochemical porous electrode model is developed,in which the porosity is affected by the silicon expansion and the local constraints.The modeling results suggest that the weaker constraint of the silicon layer in the SG electrode leads to a more insignificant decrease in porosity,and consequently,the more stable cycling performance.The findings of this work provide new insights into the structural design of Si-based electrodes.展开更多
Al/α-PbO2/β-PbO2 composite electrodes doped with rare earth oxide （CeO2） were prepared by anodic oxidation method investigate the influence of nano-CeO2 dopants on the properties of Al/α-PbO2/β-PbO2-CeO2 electro...Al/α-PbO2/β-PbO2 composite electrodes doped with rare earth oxide （CeO2） were prepared by anodic oxidation method investigate the influence of nano-CeO2 dopants on the properties of Al/α-PbO2/β-PbO2-CeO2 electrodes and the impact of α-PbO2 as the intermediate layer. The results show that using α-PbO2 as the intermediate layer will benefit the crystallization of β-PbO2 and β-PbO2 is more suitable as the surface layer than α-PbO2. CeO2 dopants change the crystallite size and crystal structure, enhance the catalytic activity, and even change the deposition mechanism of PbO2. The doping of CeO2 in the PbO2 electrodes can enhance the electro-catalytic activity, which is helpful for oxygen evolution, and therefore reduce the cell voltage.展开更多
In order to investigate the effect of solid particles dopants on physicochemical properties of α-PbO2 electrodes, a-PbO2 composite electrodes doped with nano-TiO2 and nano-CeO2 particles were respectively prepared on...In order to investigate the effect of solid particles dopants on physicochemical properties of α-PbO2 electrodes, a-PbO2 composite electrodes doped with nano-TiO2 and nano-CeO2 particles were respectively prepared on A1/conductive coating electrodes in 4 mol/L NaOH solution with addition of PbO until saturation by anodic codeposition. The electrodeposition mechanism, morphology, composition and structure of the composite electrodes were characterized by cyclic voltarnmogram （CV）, SEM, EDAX and XRD. Results show that the doping solid particles can not change reaction mechanism of α-PbO2 electrode in alkaline or acid plating bath, but can improve deposition rate and reduce oxygen evolution potential. The doping solid particles can inhibit the growth of a-PbO2 unit cell and improve specific surface area. The diffraction peak intensity of a-PbO2-CeO2-TiO2 composite electrode is lower than that of pure a-PbO2 electrode. The electrocatalytic activity of a-PbO2-2.12%CEO2-3.71%TIO2 composite electrode is the best. The Guglielmi model for CeO2 and TiO2 codeposition with a-PbO2 is also pronosed.展开更多
Al/conductive coating/α-Pb O2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2 composite electrode material was prepared on Al/conductive coating/α-PbO 2-Ce O2-Ti O2 substrate by electrochemical oxidation co-deposition technique...Al/conductive coating/α-Pb O2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2 composite electrode material was prepared on Al/conductive coating/α-PbO 2-Ce O2-Ti O2 substrate by electrochemical oxidation co-deposition technique. The effects of current density on the chemical composition, electrocatalytic activity, and stability of the composite anode material were investigated by energy dispersive X-ray spectroscopy（EDXS）, anode polarization curves, quasi-stationary polarization（Tafel） curves, electrochemical impedance spectroscopy（EIS）, scanning electron microscopy（SEM）, and X-ray diffraction（XRD）. Results reveal that the composite electrode obtained at 1 A/dm2 possesses the lowest overpotential（0.610 V at 500 A/m2） for oxygen evolution, the best electrocatalytic activity, the longest service life（360 h at 40 °C in 150 g/L H2SO4 solution under 2 A/cm2）, and the lowest cell voltage（2.75 V at 500 A/m2）. Furthermore, with increasing current density, the coating exhibits grain growth and the decrease of content of Mn O2. Only a slight effect on crystalline structure is observed.展开更多
This article proposes a new type of electrode for micro-electro-discharge machining (micro-EDM) , which can produce ultra fine micro components from various kinds of materials including those that cannot be processed ...This article proposes a new type of electrode for micro-electro-discharge machining (micro-EDM) , which can produce ultra fine micro components from various kinds of materials including those that cannot be processed by the silicon or the Litho-graphie Galvanoformung Abformung (LIGA) processings. This electrode is made by way of the electrodeposition process on the basis of the difference between the discharging performance of the electrodeposited coating and that of the matrix to ensure uniform wear of ele...展开更多
The synthetic routes of porous carbons and the applications of the functional porous carbon-based composite electrode materials for lithium secondary batteries are reviewed. The synthetic methods have made great break...The synthetic routes of porous carbons and the applications of the functional porous carbon-based composite electrode materials for lithium secondary batteries are reviewed. The synthetic methods have made great breakthroughs to control the pore size and volume, wall thickness, surface area, and connectivity of porous carbons, which result in the development of functional porous carbon-based composite electrode materials. The effects of porous carbons on the electrochemical properties are further discussed. The porous carbons as ideal matrixes to incorporate active materials make a great improvement on the electrochemical properties because of high surface area and pore volume, excellent electronic conductivity, and strong adsorption capacity. Large numbers of the composite electrode materials have been used for the devices of electrochemical energy conversion and storage, such as lithium-ion batteries （LIBs）, Li-S batteries, and Li-O2 batteries. It is believed that functional porous carbon-based composite electrode materials will continuously contribute to the field of lithium secondary batteries.展开更多
Metal-organic framework(MOF)and its derivatives have low-cost,controllable structure,and good catalytic performance,which are often used in the electrochemical field.In this work,SnO_(2)in situ modified graphite felt(...Metal-organic framework(MOF)and its derivatives have low-cost,controllable structure,and good catalytic performance,which are often used in the electrochemical field.In this work,SnO_(2)in situ modified graphite felt(SnO_(2)/GF)is prepared by hydrothermal method then simple thermal treatment using Sn-based MOF(Sn-MOF)as precursor.SnO_(2)is uniformly and firmly distributed on the GF surface rather than the common agglomeration and poor bonding of metal oxides on carbon-based electrodes,providing stable active centers for the VO^(2+)/VO_(2)^(+)and V^(2+)/V^(3+)redox reactions.At250 mA·cm^(-2),the energy efficiency of the battery with SnO_(2)/GF remains at 63.2%,while the blank one has failed.The former battery,at 100 mA·cm^(-2),has higher energy efficiency and good cycle stability(over 200 cycles).The battery performance of this study is better than that of most previous report in metal oxide-related work.This work obtains high-performance composite electrode by simple treatment of MOF,which provides a reference for the application of MOF in vanadium redox flow battery.展开更多
Taking the nano-sized carbon black and aniline monomer as precursor and （NH4）2S2O6 as oxidant, the well coated C/polyaniline（C/PANI） composite materials were prepared by in situ polymerization of the aniline on th...Taking the nano-sized carbon black and aniline monomer as precursor and （NH4）2S2O6 as oxidant, the well coated C/polyaniline（C/PANI） composite materials were prepared by in situ polymerization of the aniline on the surface of well-dispersed nano-sized carbon black for supercapacitor. The micro-structure of the C/PANI composite electrode materials were analyzed by SEM. The electrochemical properties of C/ PANI and PANI composite electrode were characterized by means of the galvanostatic charge-discharge experiment, cyclic voltammetric measurement and impedance spectroscopy analysis. The results show that by adding the nano-sized carbon black in the process of chemical polymerization of the aniline, the polyaniline can be in situ polymerized and well-coated onto the carbon black particles, which may effectively improve the aggregation of particles and the electrolyte penetration. What’s more , the maximum of specific capacitance of C/PANI electrode 437.6F·g -1 can be attained. Compared with PANI electrode, C/PANI electrode shows more desired capacitance characteristics, smaller internal resistance and better cycle performance.展开更多
This work describes the electrochemical behaviour of ibuprofen on two types of multi-walled carbon nanotubes based composite electrodes, i.e., multi-walled carbon nanotubes-epoxy （MWCNT） and silver-modified zeolite-...This work describes the electrochemical behaviour of ibuprofen on two types of multi-walled carbon nanotubes based composite electrodes, i.e., multi-walled carbon nanotubes-epoxy （MWCNT） and silver-modified zeolite-multi-wailed carbon nanotubes-epoxy （AgZMWCNT） composites electrodes. The composite electrodes were obtained using two-roll mill procedure. SEM images of surfaces of the composites revealed a homogeneous distribution of the composite components within the epoxy matrix. AgZMWCNT composite electrode exhibited the better electrical conductivity and larger electroactive surface area. The electrochemical determination of ibuprofen （IBP） was achieved using AgZMWCNT by cyclic voltammetry, differential-pulsed voltammetry, square-wave voltammetry and chronoamperometry. The IBP degradation occurred on both composite electrodes under controlled electrolysis at 1.2 and 1.75 V vs. Ag/AgCl, and IBP concentration was determined comparatively by differential-pulsed voltammetry, under optimized conditions using AgZMWCNT electrode and UV-Vis spectrophotometry methods to determine the IBP degradation performance for each electrode. AgZMWCNT electrode exhibited a dual character allowing a double application in IBP degradation process and its control.展开更多
Perovskite solar cells(PSCs)have become the represent-atives of next generation of photovoltaics;nevertheless,their stability is insufficient for large scale deployment,particularly the reverse bias stability.Here,we ...Perovskite solar cells(PSCs)have become the represent-atives of next generation of photovoltaics;nevertheless,their stability is insufficient for large scale deployment,particularly the reverse bias stability.Here,we propose a transparent conducting oxide(TCO)and low-cost metal composite electrode to improve the stability of PSCs without sacrificing the efficiency.The TCO can block ion migrations and chemical reactions between the metal and perovskite,while the metal greatly enhances the conductivity of the composite electrode.As a result,composite electrode-PSCs achieved a power conversion efficiency(PCE)of 23.7%(certified 23.2%)and exhibited excellent stability,maintaining 95%of the initial PCE when applying a reverse bias of 4.0 V for 60 s and over 92%of the initial PCE after 1000 h continuous light soaking.This composite electrode strategy can be extended to different combinations of TCOs and metals.It opens a new avenue for improving the stability of PSCs.展开更多
The structure and proton conducting mechanism of solid polymer electrolyte (SPE) are described. Since the conductivity of electrolyte is important in SPE electrochemical cell research and development, we investigate q...The structure and proton conducting mechanism of solid polymer electrolyte (SPE) are described. Since the conductivity of electrolyte is important in SPE electrochemical cell research and development, we investigate quantitatively the conductivity of Nafion membrane and its dependence on temperature and relative humidity. Experimental results show that the conductivity of Nafion membrane increases with temperature and relative humidity. We also reports on the preparation and development of SPE membrane electrode with the emphasis on the mixture pressing method and impregnation-reduction process to prepare SPE composite electrode assemblies and their application to electrochemical sensors. We also investigate and fabricate a potentiometric electrochemical sensor of hydrogen and ethylene to measure the hydrogen and ethylene partial pressure.展开更多
Composite electrodes prepared by cation exchange resins and activated carbon(AC)were used to adsorb Ⅴ(Ⅳ)in capacitive deionization(CDI).The electrode made of middle resin size(D860/AC M)had the largest specific surf...Composite electrodes prepared by cation exchange resins and activated carbon(AC)were used to adsorb Ⅴ(Ⅳ)in capacitive deionization(CDI).The electrode made of middle resin size(D860/AC M)had the largest specific surface area and mesoporous content than two other composite electrodes.Electrochemical analysis showed that D860/AC M presents higher specific capacitance and electrical double layer capacitor than the others,and significantly lower internal diffusion impedance.Thus,D860/AC M exhibits the highest adsorption capacity and rate of Ⅴ(Ⅳ)among three electrodes.The intra-particle diffusion model fits well in the initial adsorption stage,while the liquid film diffusion model is more suitable for fitting at the later stage.The pseudo-second-order kinetic model is suited for the entire adsorption process.The adsorption of Ⅴ(Ⅳ)on the composite electrode follows that of the Freundlich isotherm.Thermodynamic analysis indicates that the adsorption of Ⅴ(Ⅳ)is an exothermic process with entropy reduction,and the electric field force plays a dominant role in the CDI process.This work aims to improve our understanding of the ion adsorption behaviors and mechanisms on the composite electrodes in CDI.展开更多
The efficient thickness of a composite electrode for solid oxide fuel cells was directly calculated by developing a physical model taking into account of the charge transfer process, the oxygen ion and electron transp...The efficient thickness of a composite electrode for solid oxide fuel cells was directly calculated by developing a physical model taking into account of the charge transfer process, the oxygen ion and electron transportation, and the microstructure characteristics of the electrode. The efficient thickness, which is defined as the electrode thickness corresponding to the minimum electrode polarization resistance, is formulated as a function of charge transfer resistivity, effective resistivity to ion and electron transport, and three-phase boundary length per unit volume. The model prediction is compared with the experimental reports to check the validity. Simulation is performed to show the effect of microstructure, intrinsic material properties, and electrode reaction mechanism on the efficient thickness. The results suggest that when an electrode is fabricated, its thickness should be controlled regarding its composition, particle size of its components, the intrinsic ionic and electronic conductivities,and its reaction mechanisms as well as the expected operation temperatures. The sensitivity of electrode polarization resistance to its thickness is also discussed.展开更多
The development of a simple, efficient and sensitive sensor for dissolved oxygen is proposed using a novel type of porous carbon composite membrane/glassy carbon electrode based on the low-cost common filter paper by ...The development of a simple, efficient and sensitive sensor for dissolved oxygen is proposed using a novel type of porous carbon composite membrane/glassy carbon electrode based on the low-cost common filter paper by a simple method. The resulting device exhibited excellent electrocatalytic activities toward the oxygen reduction reaction. Scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements demonstrated that the porous morphology and uniformly dispersed Fe;C nanoparticles of the PCCM play an important role in the oxygen reduction reaction. A linear response range from 2mmol/L up to 110 mmol/L and a detection limit of 1.4 mmol/L was obtained with this sensor. The repeatability of the proposed sensor,evaluated in terms of relative standard deviation, was 3.0%. The successful fabrication of PCCM/GC electrode may promote the development of new porous carbon oxygen reduction reaction material for the oxygen reduction sensor.展开更多
Lithium-ion batteries suffer from mechano–electrochemical coupling problems that directly determine the battery life. In this paper, we investigate the electrode electrochemical performance under stress conditions, w...Lithium-ion batteries suffer from mechano–electrochemical coupling problems that directly determine the battery life. In this paper, we investigate the electrode electrochemical performance under stress conditions, where seven tensile/compressive stresses are designed and loaded on electrodes, thereby decoupling mechanics and electrochemistry through incremental stress loads. Four types of multi-group electrochemical tests under tensile/compressive stress loading and normal package loading are performed to quantitatively characterize the effects of tensile stress and compressive stress on cycle performance and the kinetic performance of a silicon composite electrode. Experiments show that a tensile stress improves the electrochemical performance of a silicon composite electrode, exhibiting increased specific capacity and capacity retention rate, reduced energy dissipation rate and impedances, enhanced reactivity, accelerated ion/electron migration and diffusion, and reduced polarization. Contrarily, a compressive stress has the opposite effect, inhibiting the electrochemical performance. The stress effect is nonlinear, and a more obvious suppression via compressive stress is observed than an enhancement via tensile stress. For example, a tensile stress of 675 k Pa increases diffusion coefficient by 32.5%, while a compressive stress reduces it by 35%. Based on the experimental results, the stress regulation mechanism is analyzed. Tensile stress loads increase the pores of the electrode material microstructure, providing more deformation spaces and ion/electron transport channels. This relieves contact compressive stress, strengthens diffusion/reaction, and reduces the degree of damage and energy dissipation. Thus, the essence of stress enhancement is that it improves and optimizes diffusion, reaction and stress in the microstructure of electrode material as well as their interactions via physical morphology.展开更多
Direct carbon solid oxide fuel cells(DC-SOFCs)are promising,green,and efficient power-generating devices that are fueled by solid carbons and comprise all-solid-state structures.Developing suitable anode materials for...Direct carbon solid oxide fuel cells(DC-SOFCs)are promising,green,and efficient power-generating devices that are fueled by solid carbons and comprise all-solid-state structures.Developing suitable anode materials for DC-SOFCs is a substantial scientific challenge.Herein we investigated the use of La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3)-δ−Ce_(0.8)Gd_(0.2)O_(1.9)(LSCM−GDC)composite electrodes as anodes for La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3)-δelectrolyte-based DC-SOFCs,with Camellia oleifera shell char as the carbon fuel.The LSCM−GDC-anode DC-SOFC delivered a maximum power density of 221 mW/cm^(2) at 800℃ and it significantly improved to 425 mW/cm^(2) after Ni nanoparticles were introduced into the LSCM−GDC anode through wet impregnation.The microstructures of the prepared anodes were characterized,and the stability of the anode in a DC-SOFC and the influence of catalytic activity on open circuit voltage were studied.The above results indicate that LSCM–GDC anode is promising to be applied in DC-SOFCs.展开更多
The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focus...The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focuses on the development of sulphonated polyether ether ketone（SPEEK） based membranes and caesium salt of silico-tungstic acid（Cs Si WA） matrix compared with one of the transition metal oxides such as titanium dioxide（TiO2）, silicon dioxide（SiO2） and zirconium dioxide（ZrO2）. The resultant membranes have been characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ion exchange capacity（IEC）, water uptake and atomic force microscopy. Comparative studies on the performance of MEAs were also conducted utilizing impregnation-reduction and conventional brush coating methods. The PEM electrolysis performance of SPEEK-Cs Si WA-ZrO2 composite membrane was more superior than that of other membranes involved in this study. Electrochemical characterization shows that a maximum current density of 1.4 A/cm^2 was achieved at 60 °C, explained by an increased concentration of protonic sites available at the interface.展开更多
Au-Pt/SnO2/GC composite electrode was prepared by self-assembling Au-Pt nanoparticles on SnO2 film, which was deposited on actived glassy carbon （GC）. Atomic force microscopy （AFM） and scanning electron microscopy...Au-Pt/SnO2/GC composite electrode was prepared by self-assembling Au-Pt nanoparticles on SnO2 film, which was deposited on actived glassy carbon （GC）. Atomic force microscopy （AFM） and scanning electron microscopy （SEM） images revealed that dense and uniform Au-Pt particles with 25-nm diameter were dispersed on SnO2 film. X-ray photoelectron spectroscopy （XPS） results proved that there was an interaction between Au-Pt nanoparticles and SnO2 support. Electrochemical experiments showed that Au-Pt/SnOz/GC composite electrode had a good electrocatalytic activity to the oxidation of methanol展开更多
基金supported by the Fundamental Research Funds for the Central Universities(WK2090000055)Anhui Provincial Natural Science Foundation of China(2308085QG231).
文摘As a negative electrode material for lithium-ion batteries,silicon monoxide(SiO)suffers from dramatic volume changes during cycling,causing excessive stress within the electrode and resulting in electrode deformation and fragmentation.This ultimately leads to a decrease in cell capacity.The trends of volume expansion and capacity change of the SiO/graphite(SiO/C)composite electrode during cycling were investigated via in situ expansion monitoring.First,a series of expansion test schemes were designed,and the linear relationship between negative electrode expansion and cell capacity degradation was quantitatively analyzed.Then,the effects of different initial pressures on the long-term cycling performance of the cell were evaluated.Finally,the mechanism of their effects was analyzed by scanning electron microscope.The results show that after 50 cycles,the cell capacity decreases from 2.556 mAh to 1.689 mAh,with a capacity retention ratio(CRR)of only 66.08%.A linear relationship between the capacity retention ratio and thickness expansion was found.Electrochemical measurements and scanning electron microscope images demonstrate that intense stress inhibits the lithiation of the negative electrode and that the electrode is more susceptible to irreversible damage during cycling.Overall,these results reveal the relationship between the cycling performance of SiO and the internal pressure of the electrode from a macroscopic point of view,which provides some reference for the application of SiO/C composite electrodes in lithium-ion batteries.
基金supported by the National Natural Science Foundation of China(Grants Nos.12172102 and 12372097)the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2022013).
文摘The silicon-graphite(Si-C)composite electrode is considered a promising candidate for next-generation commercial electrodes due to its high capacity.However,lithium-ion batteries with silicon electrodes often experience capacity fading and poor cyclic performance,primarily due to the mechanical degradation of the solid-electrolyte interphase(SEI).In this work,we present a homogenized constitutive model for Si-C composite electrodes under finite deformation,incorporating lithium-ion concentration-dependent properties.We perform a wrinkling analysis and systematically examine the influence of key parameters,such as modulus and thickness ratios,on the critical conditions for instability.Additionally,we investigate the ratcheting effect across varying silicon contents.Our findings reveal that maintaining the silicon content within an optimal range effectively reduces plastic accumulation during charge–discharge cycles.These insights provide crucial guidance for optimizing the design and fabrication of Si–C electrode systems,enhancing their durability and performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.12072183,12472174,and 12421002).
文摘The recently reported silicon/graphite(Si/Gr)composite electrode with a layered structure is a promising approach to achieve high capacity and stable cycling of Si-based electrodes in lithium-ion batteries.However,there is still a need to clarify why particular layered structures are effective and why others are ineffective or even detrimental.In this work,an unreported mechanism dominated by the porosity evolution of electrodes is proposed for the degradation behavior of layered Si/Gr electrodes.First,the effect of layering sequence on the overall electrode performance is investigated experimentally,and the results suggest that the cycling performance of the silicon-on-graphite(SG)electrode is much superior to that of the graphite-on-silicon electrode.To explain this phenomenon,a coupled mechanical-electrochemical porous electrode model is developed,in which the porosity is affected by the silicon expansion and the local constraints.The modeling results suggest that the weaker constraint of the silicon layer in the SG electrode leads to a more insignificant decrease in porosity,and consequently,the more stable cycling performance.The findings of this work provide new insights into the structural design of Si-based electrodes.
基金Project(50964008)supported by the National Natural Science Foundation of ChinaProject(2010287)supported by Analysis and Testing Foundation of Kunming University of Science and Technology,China
文摘Al/α-PbO2/β-PbO2 composite electrodes doped with rare earth oxide （CeO2） were prepared by anodic oxidation method investigate the influence of nano-CeO2 dopants on the properties of Al/α-PbO2/β-PbO2-CeO2 electrodes and the impact of α-PbO2 as the intermediate layer. The results show that using α-PbO2 as the intermediate layer will benefit the crystallization of β-PbO2 and β-PbO2 is more suitable as the surface layer than α-PbO2. CeO2 dopants change the crystallite size and crystal structure, enhance the catalytic activity, and even change the deposition mechanism of PbO2. The doping of CeO2 in the PbO2 electrodes can enhance the electro-catalytic activity, which is helpful for oxygen evolution, and therefore reduce the cell voltage.
基金Project(51004056) supported by the National Natural Science Foundation of ChinaProject(KKZ6201152009) supported by the Opening Foundation of Key Laboratory of Inorganic Coating Materials,Chinese Academy of Sciences+2 种基金Project(2010ZC052) supported by the Applied Basic Research Foundation of Yunnan Province,ChinaProject(20125314110011) supported by the Specialized Research Fund for the Doctoral Program of Higher EducationProject(2010247) supported by Analysis & Testing Foundation of Kunming University of Science and Technology,China
文摘In order to investigate the effect of solid particles dopants on physicochemical properties of α-PbO2 electrodes, a-PbO2 composite electrodes doped with nano-TiO2 and nano-CeO2 particles were respectively prepared on A1/conductive coating electrodes in 4 mol/L NaOH solution with addition of PbO until saturation by anodic codeposition. The electrodeposition mechanism, morphology, composition and structure of the composite electrodes were characterized by cyclic voltarnmogram （CV）, SEM, EDAX and XRD. Results show that the doping solid particles can not change reaction mechanism of α-PbO2 electrode in alkaline or acid plating bath, but can improve deposition rate and reduce oxygen evolution potential. The doping solid particles can inhibit the growth of a-PbO2 unit cell and improve specific surface area. The diffraction peak intensity of a-PbO2-CeO2-TiO2 composite electrode is lower than that of pure a-PbO2 electrode. The electrocatalytic activity of a-PbO2-2.12%CEO2-3.71%TIO2 composite electrode is the best. The Guglielmi model for CeO2 and TiO2 codeposition with a-PbO2 is also pronosed.
基金Projects(51004056,51004057)supported by the National Natural Science Foundation of ChinaProject(KKZ6201152009)supported by the Opening Foundation of Key Laboratory of Inorganic Coating Materials,Chinese Academy of Sciences+2 种基金Project(2010ZC052)supported by the Applied Basic Research Foundation of Yunnan Province,ChinaProject(20125314110011)supported by the Specialized Research Fund for the Doctoral Program of Higher Education,ChinaProject(2010247)supported by Analysis&Testing Foundation of Kunming University of Science and Technology,China
文摘Al/conductive coating/α-Pb O2-Ce O2-Ti O2/β-PbO 2-MnO 2-WC-Zr O2 composite electrode material was prepared on Al/conductive coating/α-PbO 2-Ce O2-Ti O2 substrate by electrochemical oxidation co-deposition technique. The effects of current density on the chemical composition, electrocatalytic activity, and stability of the composite anode material were investigated by energy dispersive X-ray spectroscopy（EDXS）, anode polarization curves, quasi-stationary polarization（Tafel） curves, electrochemical impedance spectroscopy（EIS）, scanning electron microscopy（SEM）, and X-ray diffraction（XRD）. Results reveal that the composite electrode obtained at 1 A/dm2 possesses the lowest overpotential（0.610 V at 500 A/m2） for oxygen evolution, the best electrocatalytic activity, the longest service life（360 h at 40 °C in 150 g/L H2SO4 solution under 2 A/cm2）, and the lowest cell voltage（2.75 V at 500 A/m2）. Furthermore, with increasing current density, the coating exhibits grain growth and the decrease of content of Mn O2. Only a slight effect on crystalline structure is observed.
基金National Natural Science Foundation of China (50635040)
文摘This article proposes a new type of electrode for micro-electro-discharge machining (micro-EDM) , which can produce ultra fine micro components from various kinds of materials including those that cannot be processed by the silicon or the Litho-graphie Galvanoformung Abformung (LIGA) processings. This electrode is made by way of the electrodeposition process on the basis of the difference between the discharging performance of the electrodeposited coating and that of the matrix to ensure uniform wear of ele...
基金supported by the Programs of National 973 (2011CB935900)NSFC (51231003 and 21231005)+1 种基金111 Project (B12015)Tianjin High-Tech (10SYSYJC27600)
文摘The synthetic routes of porous carbons and the applications of the functional porous carbon-based composite electrode materials for lithium secondary batteries are reviewed. The synthetic methods have made great breakthroughs to control the pore size and volume, wall thickness, surface area, and connectivity of porous carbons, which result in the development of functional porous carbon-based composite electrode materials. The effects of porous carbons on the electrochemical properties are further discussed. The porous carbons as ideal matrixes to incorporate active materials make a great improvement on the electrochemical properties because of high surface area and pore volume, excellent electronic conductivity, and strong adsorption capacity. Large numbers of the composite electrode materials have been used for the devices of electrochemical energy conversion and storage, such as lithium-ion batteries （LIBs）, Li-S batteries, and Li-O2 batteries. It is believed that functional porous carbon-based composite electrode materials will continuously contribute to the field of lithium secondary batteries.
基金the National Natural Science Foundation of China(Nos.51872090 and 51772097)Hebei Natural Science Fund for Distinguished Young Scholar(No.E2019209433)+1 种基金the Youth Talent Program of Hebei Provincial Education Department(No.BJ2018020)the Natural Science Foundation of Hebei Province(No.E2020209151)。
文摘Metal-organic framework(MOF)and its derivatives have low-cost,controllable structure,and good catalytic performance,which are often used in the electrochemical field.In this work,SnO_(2)in situ modified graphite felt(SnO_(2)/GF)is prepared by hydrothermal method then simple thermal treatment using Sn-based MOF(Sn-MOF)as precursor.SnO_(2)is uniformly and firmly distributed on the GF surface rather than the common agglomeration and poor bonding of metal oxides on carbon-based electrodes,providing stable active centers for the VO^(2+)/VO_(2)^(+)and V^(2+)/V^(3+)redox reactions.At250 mA·cm^(-2),the energy efficiency of the battery with SnO_(2)/GF remains at 63.2%,while the blank one has failed.The former battery,at 100 mA·cm^(-2),has higher energy efficiency and good cycle stability(over 200 cycles).The battery performance of this study is better than that of most previous report in metal oxide-related work.This work obtains high-performance composite electrode by simple treatment of MOF,which provides a reference for the application of MOF in vanadium redox flow battery.
基金Project(2005CB623703) supported by the National Basic Research Program of China project(5JJ30103) supported bythe Natural Science Foundation of Hunan Province
文摘Taking the nano-sized carbon black and aniline monomer as precursor and （NH4）2S2O6 as oxidant, the well coated C/polyaniline（C/PANI） composite materials were prepared by in situ polymerization of the aniline on the surface of well-dispersed nano-sized carbon black for supercapacitor. The micro-structure of the C/PANI composite electrode materials were analyzed by SEM. The electrochemical properties of C/ PANI and PANI composite electrode were characterized by means of the galvanostatic charge-discharge experiment, cyclic voltammetric measurement and impedance spectroscopy analysis. The results show that by adding the nano-sized carbon black in the process of chemical polymerization of the aniline, the polyaniline can be in situ polymerized and well-coated onto the carbon black particles, which may effectively improve the aggregation of particles and the electrolyte penetration. What’s more , the maximum of specific capacitance of C/PANI electrode 437.6F·g -1 can be attained. Compared with PANI electrode, C/PANI electrode shows more desired capacitance characteristics, smaller internal resistance and better cycle performance.
基金supported by the strategic grant POSDRU/88/1.5/S/50783POSDRU/21/1.5/G/13798+1 种基金POSDRU/89/1.5/S/57649 co-financed by the European Social Fund - Investing in People,within the Sectoral Operational Programme Human Resources Development 2007-2013partially by the PN II-RU-PD129/2010 and PN II Ideas 165/2011
文摘This work describes the electrochemical behaviour of ibuprofen on two types of multi-walled carbon nanotubes based composite electrodes, i.e., multi-walled carbon nanotubes-epoxy （MWCNT） and silver-modified zeolite-multi-wailed carbon nanotubes-epoxy （AgZMWCNT） composites electrodes. The composite electrodes were obtained using two-roll mill procedure. SEM images of surfaces of the composites revealed a homogeneous distribution of the composite components within the epoxy matrix. AgZMWCNT composite electrode exhibited the better electrical conductivity and larger electroactive surface area. The electrochemical determination of ibuprofen （IBP） was achieved using AgZMWCNT by cyclic voltammetry, differential-pulsed voltammetry, square-wave voltammetry and chronoamperometry. The IBP degradation occurred on both composite electrodes under controlled electrolysis at 1.2 and 1.75 V vs. Ag/AgCl, and IBP concentration was determined comparatively by differential-pulsed voltammetry, under optimized conditions using AgZMWCNT electrode and UV-Vis spectrophotometry methods to determine the IBP degradation performance for each electrode. AgZMWCNT electrode exhibited a dual character allowing a double application in IBP degradation process and its control.
基金supported by National Natural Science Foundation of China(No.21872080)National Key Research and Development Program of China(2022YFB3803304)+2 种基金supported by Tsinghua University Initiative Scientific Research Program(20221080065,20223080044)The State Key Laboratory of Power System and Generation Equipment(Nos.SKLD21Z03 and SKLD20M03)the Chinese Thousand Talents Program for Young Professionals.
文摘Perovskite solar cells(PSCs)have become the represent-atives of next generation of photovoltaics;nevertheless,their stability is insufficient for large scale deployment,particularly the reverse bias stability.Here,we propose a transparent conducting oxide(TCO)and low-cost metal composite electrode to improve the stability of PSCs without sacrificing the efficiency.The TCO can block ion migrations and chemical reactions between the metal and perovskite,while the metal greatly enhances the conductivity of the composite electrode.As a result,composite electrode-PSCs achieved a power conversion efficiency(PCE)of 23.7%(certified 23.2%)and exhibited excellent stability,maintaining 95%of the initial PCE when applying a reverse bias of 4.0 V for 60 s and over 92%of the initial PCE after 1000 h continuous light soaking.This composite electrode strategy can be extended to different combinations of TCOs and metals.It opens a new avenue for improving the stability of PSCs.
基金Supported by the National Natural Science Foundation of China (No. 29875002) and the Natural Science Foundation of Beijing (No. 2002017).
文摘The structure and proton conducting mechanism of solid polymer electrolyte (SPE) are described. Since the conductivity of electrolyte is important in SPE electrochemical cell research and development, we investigate quantitatively the conductivity of Nafion membrane and its dependence on temperature and relative humidity. Experimental results show that the conductivity of Nafion membrane increases with temperature and relative humidity. We also reports on the preparation and development of SPE membrane electrode with the emphasis on the mixture pressing method and impregnation-reduction process to prepare SPE composite electrode assemblies and their application to electrochemical sensors. We also investigate and fabricate a potentiometric electrochemical sensor of hydrogen and ethylene to measure the hydrogen and ethylene partial pressure.
基金financially supported by the National Natural Science Foundation of China(No.51874222).
文摘Composite electrodes prepared by cation exchange resins and activated carbon(AC)were used to adsorb Ⅴ(Ⅳ)in capacitive deionization(CDI).The electrode made of middle resin size(D860/AC M)had the largest specific surface area and mesoporous content than two other composite electrodes.Electrochemical analysis showed that D860/AC M presents higher specific capacitance and electrical double layer capacitor than the others,and significantly lower internal diffusion impedance.Thus,D860/AC M exhibits the highest adsorption capacity and rate of Ⅴ(Ⅳ)among three electrodes.The intra-particle diffusion model fits well in the initial adsorption stage,while the liquid film diffusion model is more suitable for fitting at the later stage.The pseudo-second-order kinetic model is suited for the entire adsorption process.The adsorption of Ⅴ(Ⅳ)on the composite electrode follows that of the Freundlich isotherm.Thermodynamic analysis indicates that the adsorption of Ⅴ(Ⅳ)is an exothermic process with entropy reduction,and the electric field force plays a dominant role in the CDI process.This work aims to improve our understanding of the ion adsorption behaviors and mechanisms on the composite electrodes in CDI.
文摘The efficient thickness of a composite electrode for solid oxide fuel cells was directly calculated by developing a physical model taking into account of the charge transfer process, the oxygen ion and electron transportation, and the microstructure characteristics of the electrode. The efficient thickness, which is defined as the electrode thickness corresponding to the minimum electrode polarization resistance, is formulated as a function of charge transfer resistivity, effective resistivity to ion and electron transport, and three-phase boundary length per unit volume. The model prediction is compared with the experimental reports to check the validity. Simulation is performed to show the effect of microstructure, intrinsic material properties, and electrode reaction mechanism on the efficient thickness. The results suggest that when an electrode is fabricated, its thickness should be controlled regarding its composition, particle size of its components, the intrinsic ionic and electronic conductivities,and its reaction mechanisms as well as the expected operation temperatures. The sensitivity of electrode polarization resistance to its thickness is also discussed.
基金the National Natural Science Foundation of China (No.21273097)the project from the State Key Laboratory of Electroanalytical Chemistry (No.2013)the Science Foundation of Jilin Province (No.20130204003GX)
文摘The development of a simple, efficient and sensitive sensor for dissolved oxygen is proposed using a novel type of porous carbon composite membrane/glassy carbon electrode based on the low-cost common filter paper by a simple method. The resulting device exhibited excellent electrocatalytic activities toward the oxygen reduction reaction. Scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements demonstrated that the porous morphology and uniformly dispersed Fe;C nanoparticles of the PCCM play an important role in the oxygen reduction reaction. A linear response range from 2mmol/L up to 110 mmol/L and a detection limit of 1.4 mmol/L was obtained with this sensor. The repeatability of the proposed sensor,evaluated in terms of relative standard deviation, was 3.0%. The successful fabrication of PCCM/GC electrode may promote the development of new porous carbon oxygen reduction reaction material for the oxygen reduction sensor.
基金Project supported by the Major Program of the National Natural Science Foundation of China(Grant No.11890680)the National Natural Science Foundation of China(Grant No.12022205)。
文摘Lithium-ion batteries suffer from mechano–electrochemical coupling problems that directly determine the battery life. In this paper, we investigate the electrode electrochemical performance under stress conditions, where seven tensile/compressive stresses are designed and loaded on electrodes, thereby decoupling mechanics and electrochemistry through incremental stress loads. Four types of multi-group electrochemical tests under tensile/compressive stress loading and normal package loading are performed to quantitatively characterize the effects of tensile stress and compressive stress on cycle performance and the kinetic performance of a silicon composite electrode. Experiments show that a tensile stress improves the electrochemical performance of a silicon composite electrode, exhibiting increased specific capacity and capacity retention rate, reduced energy dissipation rate and impedances, enhanced reactivity, accelerated ion/electron migration and diffusion, and reduced polarization. Contrarily, a compressive stress has the opposite effect, inhibiting the electrochemical performance. The stress effect is nonlinear, and a more obvious suppression via compressive stress is observed than an enhancement via tensile stress. For example, a tensile stress of 675 k Pa increases diffusion coefficient by 32.5%, while a compressive stress reduces it by 35%. Based on the experimental results, the stress regulation mechanism is analyzed. Tensile stress loads increase the pores of the electrode material microstructure, providing more deformation spaces and ion/electron transport channels. This relieves contact compressive stress, strengthens diffusion/reaction, and reduces the degree of damage and energy dissipation. Thus, the essence of stress enhancement is that it improves and optimizes diffusion, reaction and stress in the microstructure of electrode material as well as their interactions via physical morphology.
基金Project(2019YFC1907405)supported by the National Key R&D Program of ChinaProject(GJJ200809)supported by the Education Department Project Fund of Jiangxi Province,ChinaProject(2020BAB214021)supported by the Natural Science Foundation of Jiangxi Province,China。
文摘Direct carbon solid oxide fuel cells(DC-SOFCs)are promising,green,and efficient power-generating devices that are fueled by solid carbons and comprise all-solid-state structures.Developing suitable anode materials for DC-SOFCs is a substantial scientific challenge.Herein we investigated the use of La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3)-δ−Ce_(0.8)Gd_(0.2)O_(1.9)(LSCM−GDC)composite electrodes as anodes for La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3)-δelectrolyte-based DC-SOFCs,with Camellia oleifera shell char as the carbon fuel.The LSCM−GDC-anode DC-SOFC delivered a maximum power density of 221 mW/cm^(2) at 800℃ and it significantly improved to 425 mW/cm^(2) after Ni nanoparticles were introduced into the LSCM−GDC anode through wet impregnation.The microstructures of the prepared anodes were characterized,and the stability of the anode in a DC-SOFC and the influence of catalytic activity on open circuit voltage were studied.The above results indicate that LSCM–GDC anode is promising to be applied in DC-SOFCs.
文摘The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focuses on the development of sulphonated polyether ether ketone（SPEEK） based membranes and caesium salt of silico-tungstic acid（Cs Si WA） matrix compared with one of the transition metal oxides such as titanium dioxide（TiO2）, silicon dioxide（SiO2） and zirconium dioxide（ZrO2）. The resultant membranes have been characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ion exchange capacity（IEC）, water uptake and atomic force microscopy. Comparative studies on the performance of MEAs were also conducted utilizing impregnation-reduction and conventional brush coating methods. The PEM electrolysis performance of SPEEK-Cs Si WA-ZrO2 composite membrane was more superior than that of other membranes involved in this study. Electrochemical characterization shows that a maximum current density of 1.4 A/cm^2 was achieved at 60 °C, explained by an increased concentration of protonic sites available at the interface.
基金supported by the High-Tech Research and Development Program of China (No. 2007AA03Z219)the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality, and the Beijing Natural Science Foundation (No. 207001)
文摘Au-Pt/SnO2/GC composite electrode was prepared by self-assembling Au-Pt nanoparticles on SnO2 film, which was deposited on actived glassy carbon （GC）. Atomic force microscopy （AFM） and scanning electron microscopy （SEM） images revealed that dense and uniform Au-Pt particles with 25-nm diameter were dispersed on SnO2 film. X-ray photoelectron spectroscopy （XPS） results proved that there was an interaction between Au-Pt nanoparticles and SnO2 support. Electrochemical experiments showed that Au-Pt/SnOz/GC composite electrode had a good electrocatalytic activity to the oxidation of methanol
