A model of Insulated Cate Bipolar(IGBT) based on analysis of nonlinear capacitances is devefoped and implemented. IGBT internal capacitances and their behavior are described as the functions of the interelectrode volt...A model of Insulated Cate Bipolar(IGBT) based on analysis of nonlinear capacitances is devefoped and implemented. IGBT internal capacitances and their behavior are described as the functions of the interelectrode voltag-es and the IGBT characteristic parameters. This model is verified by the experimenis of IRGBH50F(1200V50A). The comparison of the experimental and the simulative characteristics is obtained in the graphs.展开更多
NiCo-phosphates can deliver high specific capacitances and high electrochemical activities as pseudocapacitive electrode material for supercapacitors.In this study,The NiCo-phosphates@reduced graphene oxide(NCPO@rGO)c...NiCo-phosphates can deliver high specific capacitances and high electrochemical activities as pseudocapacitive electrode material for supercapacitors.In this study,The NiCo-phosphates@reduced graphene oxide(NCPO@rGO)composite is directly loaded on Ni foam by a simple one-step hydrothermal process.The conductive rGO sheets provides continuous electron pathways between NCPO flowers and Ni foam,allowing active electrochemical reactions throughout the whole electrode.This can solve the difficulty of low active material utility and small areal capacitances in the Ni foam-supported electrodes.At the same time,the rGO sheets creates large amount of mesopores within the electrode,which can ensure a highly open structure for electrolyte attachment and ion transport.Because of the positive effect of rGO in improving charge transfe r,the NiCo-phosphates can be fully involved in the electrochemical reactions with high utility,ensuring high specific capacitances(1416.7 F g^(-1)at 1 A g^(-1))and high-rate performances.Specially,the areal capacitance of the NCPO@rGO electrode can reach as large as 3.69 F cm^(-2)at 1 A g^(-1),which is among the highest ones in Ni foam supported electrodes.An asymmetric supercapacitor is then fabricated by NCPO@rGO as the positive material with attractive energy densities and power densities,further proving its excellent electrochemical performance.展开更多
Polarizable electrode of electric double layer capacitor was made from carbon nanotubes. The effect of acid oxidation of electrode on the specific capacitance was studied. Oxidation removed the redundant carbon, expan...Polarizable electrode of electric double layer capacitor was made from carbon nanotubes. The effect of acid oxidation of electrode on the specific capacitance was studied. Oxidation removed the redundant carbon, expanded the pore size and introducedf some kinds of functional groups on the surface of CNTs. The specific capacitance of the electrodes winth organic electrolyte was increased from 21.4 to 49.6 F/g after being oxidized at a volume ratio H2SO4 to HNO3 of 3:1.展开更多
The comb capacitances fabricated by deep reactive ion etching （RIE） process have high aspect ratio which is usually smaller than 30 ： 1 for the complicated process factors, and the combs are usually not parallel du...The comb capacitances fabricated by deep reactive ion etching （RIE） process have high aspect ratio which is usually smaller than 30 ： 1 for the complicated process factors, and the combs are usually not parallel due to the well-known micro-loading effect and other process factors, which restricts the increase of the seismic mass by increasing the thickness of comb to reduce the thermal mechanical noise and the decrease of the gap of the comb capacitances for increasing the sensitive capacitance to reduce the electrical noise. Aiming at the disadvantage of the deep RIE, a novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances is developed. One part of sensing of inertial signal of the micro-accelerometer is by the grid strip capacitances whose overlapping area is variable and which do not have the non-parallel plate＇s effect caused by the deep RIE process. Another part is by the sensing gap alterable capacitances whose gap between combs can be reduced by the actuators. The designed initial gap of the alterable comb capacitances is relatively large to depress the effect of the maximum aspect ratio （30 ： 1） of deep RIE process. The initial gap of the capacitance of the actuator is smaller than the one of the comb capacitances. The difference between the two gaps is the initial gap of the sensitive capacitor. The designed structure depresses greatly the requirement of deep RIE process. The effects of non-parallel combs on the accelerometer are also analyzed. The characteristics of the micro-accelerometer are discussed by field emission microscopy （FEM） tool ANSYS. The tested devices based on slide-film damping effect are fabricated, and the tested quality factor is 514, which shows that grid strip capacitance design can partly improve the resolution and also prove the feasibility of the designed silicon-glass anodically bonding process.展开更多
Sensitivity analysis methods help to deal with the challenges of process variation in extraction of para- sitic capacitances in an integrated circuit. The dual discrete geometric methods （DGMs）, which have been rece...Sensitivity analysis methods help to deal with the challenges of process variation in extraction of para- sitic capacitances in an integrated circuit. The dual discrete geometric methods （DGMs）, which have been recently utilized to extract parasitic capacitances, are reviewed. The computation method based on the dual DGMs for sen- sitivities of capacitances with respect to the given process parameters is presented. As the dual DGMs utilize scalar electric potential is unknown, the capacitances are obtained effectively, and then the sensitivities are calculated conveniently.展开更多
Supercapacitors are gaining popularity due to their high cycling stability,power density,and fast charge and discharge rates.Researchers are ex-ploring electrode materials,electrolytes,and separat-ors for cost-effecti...Supercapacitors are gaining popularity due to their high cycling stability,power density,and fast charge and discharge rates.Researchers are ex-ploring electrode materials,electrolytes,and separat-ors for cost-effective energy storage systems.Ad-vances in materials science have led to the develop-ment of hybrid nanomaterials,such as combining fil-amentous carbon forms with inorganic nanoparticles,to create new charge and energy transfer processes.Notable materials for electrochemical energy-stor-age applications include MXenes,2D transition met-al carbides,and nitrides,carbon black,carbon aerogels,activated carbon,carbon nanotubes,conducting polymers,carbon fibers,and nanofibers,and graphene,because of their thermal,electrical,and mechanical properties.Carbon materials mixed with conducting polymers,ceramics,metal oxides,transition metal oxides,metal hydroxides,transition metal sulfides,trans-ition metal dichalcogenide,metal sulfides,carbides,nitrides,and biomass materials have received widespread attention due to their remarkable performance,eco-friendliness,cost-effectiveness,and renewability.This article explores the development of carbon-based hybrid materials for future supercapacitors,including electric double-layer capacitors,pseudocapacitors,and hy-brid supercapacitors.It investigates the difficulties that influence structural design,manufacturing(electrospinning,hydro-thermal/solvothermal,template-assisted synthesis,electrodeposition,electrospray,3D printing)techniques and the latest car-bon-based hybrid materials research offer practical solutions for producing high-performance,next-generation supercapacitors.展开更多
In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance ...In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance this sensitivity have predominantly focused on material design and structural optimization,with surface microstructures such as wrinkles,pyramids,and micro-pillars proving effective.Although finite element modeling(FEM)has guided enhancements in CPS sensitivity across various surface designs,a theoretical understanding of sensitivity improvements remains underexplored.This paper employs sinusoidal wavy surfaces as a representative model to analytically elucidate the underlying mechanisms of sensitivity enhancement through contact mechanics.These theoretical insights are corroborated by FEM and experimental validations.Our findings underscore that optimizing material properties,such as Young’s modulus and relative permittivity,alongside adjustments in surface roughness and substrate thickness,can significantly elevate the sensitivity.The optimal performance is achieved when the amplitude-to-wavelength ratio(H/)is about 0.2.These results offer critical insights for designing ultrasensitive CPS devices,paving the way for advancements in sensor technology.展开更多
Low-electrode capacitive deionization(FCDI)is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters.However,it still suffers from inefficient charge transfer...Low-electrode capacitive deionization(FCDI)is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters.However,it still suffers from inefficient charge transfer and ion transport kinetics due to weak turbulence and low electric intensity in flow electrodes,both restricted by the current collectors.Herein,a new tip-array current collector(designated as T-CC)was developed to replace the conventional planar current collectors,which intensifies both the charge transfer and ion transport significantly.The effects of tip arrays on flow and electric fields were studied by both computational simulations and electrochemical impedance spectroscopy,which revealed the reduction of ion transport barrier,charge transport barrier and internal resistance.With the voltage increased from 1.0 to 1.5 and 2.0 V,the T-CC-based FCDI system(T-FCDI)exhibited average salt removal rates(ASRR)of 0.18,0.50,and 0.89μmol cm^(-2) min^(-1),respectively,which are 1.82,2.65,and 2.48 folds higher than that of the conventional serpentine current collectors,and 1.48,1.67,and 1.49 folds higher than that of the planar current collectors.Meanwhile,with the solid content in flow electrodes increased from 1 to 5 wt%,the ASRR for T-FCDI increased from 0.29 to 0.50μmol cm^(-2) min^(-1),which are 1.70 and 1.67 folds higher than that of the planar current collectors.Additionally,a salt removal efficiency of 99.89%was achieved with T-FCDI and the charge efficiency remained above 95%after 24 h of operation,thus showing its superior long-term stability.展开更多
Electrochemical impedance spectroscopy(EIS)is a widely used technique to monitor the electrical properties of a catalyst under electrocatalytic conditions.Although it is extensively used for research in electrocatalys...Electrochemical impedance spectroscopy(EIS)is a widely used technique to monitor the electrical properties of a catalyst under electrocatalytic conditions.Although it is extensively used for research in electrocatalysis,its effectiveness and power have not been fully harnessed to elucidate complex interfacial processes.Herein,we use the frequency dispersion parameter,n,which is extracted from EIS measurements(C_(s)=af^(n+1),-2<n<-1),to describe the dispersion characteristics of capacitance and interfacial properties of Co_(3)O_(4) before the onset of oxygen evolution reaction(OER)in alkaline conditions.We first prove that the n-value is sensitive to the interfacial electronic changes associated with Co redox processes and surface reconstruction.The n-value decreases by increasing the specific/active surface area of the catalysts.We further modify the interfacial properties by changing different components,i.e.,replacing the proton with deuterium,adding ethanol as a new oxidant,and changing the cation in the electrolyte.Intriguingly,the n-value can identify different influences on the interfacial process of proton transfer,the decrease and blocking of oxidized Co species,and the interfacial water structure.We demonstrate that the n-value extracted from EIS measurements is sensitive to the kinetic isotope effect,electrolyte cation,adsorbate surface coverage of oxidized Co species,and the interfacial water structure.Thus,it can be helpful to differentiate the multiple factors affecting the catalyst interface.These findings convey that the frequency dispersion of capacitance is a convenient and useful method to uncover the interfacial properties under electrocatalytic conditions,which helps to advance the understanding of the interfaceactivity relationship.展开更多
The development of high-performance,reproducible carbon(C)-based supercapacitors remains a significant challenge because of limited specific capacitance.Herein,we present a novel strategy for fabricating LaCoO_(x) and...The development of high-performance,reproducible carbon(C)-based supercapacitors remains a significant challenge because of limited specific capacitance.Herein,we present a novel strategy for fabricating LaCoO_(x) and cobalt(Co)-doped nanoporous C(LaCoO_(x)/Co@ZNC)through the carbonization of Co/Zn-zeolitic imidazolate framework(ZIF)crystals derived from a PVP-Co/Zn/La precursor.The unique ZIF structure effectively disrupted the graphitic C framework,preserved the Co active sites,and enhanced the electrical conductivity.The synergistic interaction between pyridinic nitrogen and Co ions further promoted redox reactions.In addition,the formation of a hierarchical pore structure through zinc sublimation facili-tated electrolyte diffusion.The resulting LaCoO_(x)/Co@ZNC exhibited exceptional electrochemical performance,delivering a remarkable specific capacitance of 2,789 F/g at 1 A/g and outstanding cycling stability with 92%capacitance retention after 3,750 cycles.Our findings provide the basis for a promising approach to advancing C-based energy storage technologies.展开更多
Vanadium nitride(VN)is a promising pseudocapacitive material due to the high theoretical capacity,rapid redox Faradaic kinetics,and appropriate potential window.Although VN shows large pseudocapacitance in alkaline el...Vanadium nitride(VN)is a promising pseudocapacitive material due to the high theoretical capacity,rapid redox Faradaic kinetics,and appropriate potential window.Although VN shows large pseudocapacitance in alkaline electrolytes,the electrochemical instability and capacity degradation of VN electrode materials present significant challenges for practical applications.Herein,the capacitance decay mechanism of VN is investigated and a simple strategy to improve cycling stability of VN supercapacitor electrodes is proposed by introducing VO_(4)^(3-)anion in KOH electrolytes.Our results show that the VN electrode is electrochemical stabilization between-1.0and-0.4 V(vs.Hg/Hg O reference electrode)in 1.0 MKOH electrolyte,but demonstrates irreversible oxidation and fast capacitance decay in the potential range of-0.4 to0 V.In situ electrochemical measurements reveal that the capacitance decay of VN from-0.4 to 0 V is ascribed to the irreversible oxidation of vanadium(V)of N–V–O species by oxygen(O)of OH^(-).The as-generated oxidization species are subsequently dissolved into KOH electrolytes,thereby undermining the electrochemical stability of VN.However,this irreversible oxidation process could be hindered by introducing VO_(4)^(3-)in KOH electrolytes.A high volumetric specific capacitance of671.9 F.cm^(-3)(1 A.cm^(-3))and excellent cycling stability(120.3%over 1000 cycles)are achieved for VN nanorod electrode in KOH electrolytes containing VO_(4)^(3-).This study not only elucidates the failure mechanism of VN supercapacitor electrodes in alkaline electrolytes,but also provides new insights into enhancing pseudocapacitive energy storage of VN-based electrode materials.展开更多
Thick and highly conductive poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate films with ideal porous structure are fulfilling as electrodes for supercapacitors.However,the homogeneous micro-structure without the...Thick and highly conductive poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate films with ideal porous structure are fulfilling as electrodes for supercapacitors.However,the homogeneous micro-structure without the aid of templates or composite presents a significant obstacle,due to the intrinsic softness of the dominant PSS component.In this study,we have successfully developed a porous configuration by employing a solvothermal approach with ethylene glycol(EG)as the solvent.The synergistic action of elevated pressure and temperature was crucial in prompting EG to tailor the microstructure of the PEDOT:PSS films by removing non-conductive PSS chains and improving PEDOT crystallinity,and the formation of a porous network.The resulting porous PEDOT:PSS films exhibited a high conductivity of 1644 S cm^(-1)and achieved a volumetric capacitance record of 270 F cm^(-3),markedly exceeding previous records.The flexible all-solid-state supercapacitor assembled by the films had an outstanding volumetric capacitance of 97.8 F cm^(-3)and an energy density of 8.7 mWh cm^(-3),which is best one for pure PEDOT:PSS-based supercapacitors.Grazing-incidence wide-angle X-ray scattering,X-ray photoelectron spectroscopy,and other characterizations were carried out to characterize the structure evolution.This work offers an effective novel method for conducting polymer morphology control and promotes PEDOT:PSS applications in energy storage field.展开更多
Noise is inevitable in electrical capacitance tomography(ECT)measurements.This paper describes the influence of noise on ECT performance for measuring gas-solids fluidized bed characteristics.The noise distribution is...Noise is inevitable in electrical capacitance tomography(ECT)measurements.This paper describes the influence of noise on ECT performance for measuring gas-solids fluidized bed characteristics.The noise distribution is approximated by the Gaussian distribution and added to experimental capacitance data with various intensities.The equivalent signal strength(Ф)that equals the signal-to-noise ratio of packed beds is used to evaluate noise levels.Results show that the Pearson correlation coefficient,which indicates the similarity of solids fraction distributions over pixels,increases with Ф,and reconstructed images are more deteriorated at lower Ф.Nevertheless,relative errors for average solids fraction and bubble size in each frame are less sensitive to noise,attributed to noise compromise caused by the process of pixel values.These findings provide useful guidance for assessing the accuracy of ECT measurements of multiphase flows.展开更多
This review explores the current state and future prospects of tactile sensing technologies in space robotics,addressing the unique challenges posed by harsh space environments such as extreme temperatures,radiation,m...This review explores the current state and future prospects of tactile sensing technologies in space robotics,addressing the unique challenges posed by harsh space environments such as extreme temperatures,radiation,microgravity,and vacuum conditions,which necessitate specialized sensor designs.We provide a detailed analysis of four primary types of tactile sensors:resistive,capacitive,piezoelectric,and optical,evaluating their operating principles,advantages,limitations,and specific applications in space exploration.Recent advancements in materials science,including the development of radiation-hardened components and flexible sensor materials,are discussed alongside innovations in sensor design and integration techniques that enhance performance and durability under space conditions.Through case studies of various space robotic systems,such as Mars rovers,robotic arms like Canadarm,humanoid robots like Robonaut,and specialized robots like Astrobee and LEMUR 3,this review highlights the crucial role of tactile sensing in enabling precise manipulation,environmental interaction,and autonomous operations in space.Moreover,it synthesizes current research and applications to underscore the transformative impact of tactile sensing technologies on space robotics and highlights their pivotal role in expanding human presence and scientific understanding in space,offering strategic insights and recommendations to guide future research and development in this critical field.展开更多
During oilfield development,a comprehensive model for assessing inter-well connectivity and connected volume within reservoirs is crucial.Traditional capacitance(TC)models,widely used in inter-well data analysis,face ...During oilfield development,a comprehensive model for assessing inter-well connectivity and connected volume within reservoirs is crucial.Traditional capacitance(TC)models,widely used in inter-well data analysis,face challenges when dealing with rapidly changing reservoir conditions over time.Additionally,TC models struggle with complex,random noise primarily caused by measurement errors in production and injection rates.To address these challenges,this study introduces a dynamic capacitance(SV-DC)model based on state variables.By integrating the extended Kalman filter(EKF)algorithm,the SV-DC model provides more flexible predictions of inter-well connectivity and time-lag efficiency compared to the TC model.The robustness of the SV-DC model is verified by comparing relative errors between preset and calculated values through Monte Carlo simulations.Sensitivity analysis was performed to compare the model performance with the benchmark,using the Qinhuangdao Oilfield as a case study.The results show that the SV-DC model accurately predicts water breakthrough times.Increases in the liquid production index and water cut in two typical wells indicate the development time of ineffective circulation channels,further confirming the accuracy and reliability of the model.The SV-DC model offers significant advantages in addressing complex,dynamic oilfield production scenarios and serves as a valuable tool for the efficient and precise planning and management of future oilfield developments.展开更多
The capacitive deionization(CDI)performance of silver(Ag)electrodes is limited by electrochemical failure induced by volumetric expansion.While carbon encapsulation and Ag size control mitigate stress concentration an...The capacitive deionization(CDI)performance of silver(Ag)electrodes is limited by electrochemical failure induced by volumetric expansion.While carbon encapsulation and Ag size control mitigate stress concentration and pulverization,achieving precise size control,suppression of aggregation,and uniform dispersion of Ag nanoparticles remains challenging.Herein,the metal-organic frameworks(MOF)-assisted pyrolysis-galvanic replacement method was employed to construct ultrafine Ag particles uniformly anchored within a three-dimensional(3D)-ordered porous carbon skeleton composite(3D Ag@NC).By utilizing the potential difference between the elements,spontaneous replacement reactions occur,effectively preventing particle agglomeration usually caused by high-temperature reduction.The in situ constructed 3D porous carbon skeleton not only promotes electron transfer and electrolyte penetration but also mitigates the volume expansion of Ag particles during electrochemical cycling.Consequently,3D Ag@NC demonstrates outstanding dechlorination performance(105.29 mg g^(-1)),high charge efficiency(0.95),and exceptional cycling stability(84.12% after 100 cycles).This galvanic replacement strategy offers valuable insights into the fabrication of other small-sized,highly dispersed metal electrode materials.展开更多
As a new electrochemical technology,capacitive deionization(CDI)has been increasingly applied in environmental water treatment and seawater desalination.In this study,functional groups modified porous hollow carbon(HC...As a new electrochemical technology,capacitive deionization(CDI)has been increasingly applied in environmental water treatment and seawater desalination.In this study,functional groups modified porous hollow carbon(HC)were synthesized as CDI electrode material for removing Na^(+)and Cl^(−)in salty water.Results showed that the average diameter of HC was approximately 180 nm,and the infrared spectrum showed that its surface was successfully modified with sulfonic and amino groups,respectively.The sulfonic acid functionalized HC(HC-S)showed better electrochemical and desalting performance than the amino-functionalized HC(HC–N),with a maximum Faradic capacity of 287.4 F/g and an adsorptive capacity of 112.97 mg/g for NaCl.Additionally,92.63%capacity retention after 100 adsorption/desorption cycles demonstrates the excellent stability of HC-S.The main findings prove that HC-S is viable as an electrodematerial for desalination by high-performance CDI applications.展开更多
Hybrid capacitive deionization(HCDI)shows promise for desalinating brackish and saline water by utilizing the pseudocapacitive properties of faradaic electrodes.Organic materials,with their low environmental impact an...Hybrid capacitive deionization(HCDI)shows promise for desalinating brackish and saline water by utilizing the pseudocapacitive properties of faradaic electrodes.Organic materials,with their low environmental impact and adaptable structures,are attractive for this application.However,their scarcity of active sites and tendency to dissolve in water-based solutions remain significant challenges.Herein,we synthesized a polynaphthalenequinoneimine(PCON)polymer with stable long-range ordered framework and rough three-dimensional floral surface morphology,along with high-density active sites provided by C=O and C=N functional groups,enabling efficient redox reactions and achieving a high Na^(+)capture capability.The synthesized PCON polymer showcases outstanding electroadsorption characteristics and notable structural robustness,attaining an impressive specific capacitance of 500.45 F g^(-1) at 1 A g^(-1) and maintaining 86.1%of its original capacitance following 5000 charge–discharge cycles.Benefiting from the superior pseudocapacitive properties of the PCON polymer,we have developed an HCDI system that not only exhibits exceptional salt removal capacity of 100.8 mg g^(-1) and a remarkable rapid average removal rate of 3.36 mg g^(-1) min-1 but also maintains 97%of its initial desalination capacity after 50 cycles,thereby distinguishing itself in the field of state-ofthe-art desalination technologies with its comprehensive performance that significantly surpasses reported organic capacitive deionization materials.Prospectively,the synthesis paradigm of the double active-sites PCON polymer may be extrapolated to other organic electrodes,heralding new avenues for the design of high-performance desalination systems.展开更多
A novel characterization method for full-matrix constants of PzT-8 piezoceramics based on local electrodes excitation using one sample is proposed to avoid resonant peaks missing and overlapping in the inversion proce...A novel characterization method for full-matrix constants of PzT-8 piezoceramics based on local electrodes excitation using one sample is proposed to avoid resonant peaks missing and overlapping in the inversion process of resonant ultrasound spectroscopy technology.Elastic matrix,which is sensitive to the resonance spectrum,is obtained by resonant ultrasound spectroscopy.Piezoelectric and dielectric matrices,which are sensitive to the capacitance of driving electrodes,are determined by capacitance inversion.The initial values of elastic constants are deviated by 30%to validate the reliability of this method.The relative errors between measured and inversed values of resonant frequencies are less than 1%and the relative errors of the capacitance are mostly less than 5%.The work has extensive applications in piezoelectric materials characterization.展开更多
Capacitive voltage transformers (CVTs) are essential in high-voltage systems. An accurate error assessment is crucial for precise energy metering. However, tracking real-time quantitative changes in capacitive voltage...Capacitive voltage transformers (CVTs) are essential in high-voltage systems. An accurate error assessment is crucial for precise energy metering. However, tracking real-time quantitative changes in capacitive voltage transformer errors, particularly minor variations in multi-channel setups, remains challenging. This paper proposes a method for online error tracking of multi-channel capacitive voltage transformers using a Co-Prediction Matrix. The approach leverages the strong correlation between in-phase channels, particularly the invariance of the signal proportions among them. By establishing a co-prediction matrix based on these proportional relationships, The influence of voltage changes on the primary measurements is mitigated. Analyzing the relationships between the co-prediction matrices over time allows for inferring true measurement errors. Experimental validation with real-world data confirms the effectiveness of the method, demonstrating its capability to continuously track capacitive voltage transformer measurement errors online with precision over extended durations.展开更多
文摘A model of Insulated Cate Bipolar(IGBT) based on analysis of nonlinear capacitances is devefoped and implemented. IGBT internal capacitances and their behavior are described as the functions of the interelectrode voltag-es and the IGBT characteristic parameters. This model is verified by the experimenis of IRGBH50F(1200V50A). The comparison of the experimental and the simulative characteristics is obtained in the graphs.
基金supported by the Fundamental Research Funds for the Central Universities of China(2652018291 and 2652018318)。
文摘NiCo-phosphates can deliver high specific capacitances and high electrochemical activities as pseudocapacitive electrode material for supercapacitors.In this study,The NiCo-phosphates@reduced graphene oxide(NCPO@rGO)composite is directly loaded on Ni foam by a simple one-step hydrothermal process.The conductive rGO sheets provides continuous electron pathways between NCPO flowers and Ni foam,allowing active electrochemical reactions throughout the whole electrode.This can solve the difficulty of low active material utility and small areal capacitances in the Ni foam-supported electrodes.At the same time,the rGO sheets creates large amount of mesopores within the electrode,which can ensure a highly open structure for electrolyte attachment and ion transport.Because of the positive effect of rGO in improving charge transfe r,the NiCo-phosphates can be fully involved in the electrochemical reactions with high utility,ensuring high specific capacitances(1416.7 F g^(-1)at 1 A g^(-1))and high-rate performances.Specially,the areal capacitance of the NCPO@rGO electrode can reach as large as 3.69 F cm^(-2)at 1 A g^(-1),which is among the highest ones in Ni foam supported electrodes.An asymmetric supercapacitor is then fabricated by NCPO@rGO as the positive material with attractive energy densities and power densities,further proving its excellent electrochemical performance.
文摘Polarizable electrode of electric double layer capacitor was made from carbon nanotubes. The effect of acid oxidation of electrode on the specific capacitance was studied. Oxidation removed the redundant carbon, expanded the pore size and introducedf some kinds of functional groups on the surface of CNTs. The specific capacitance of the electrodes winth organic electrolyte was increased from 21.4 to 49.6 F/g after being oxidized at a volume ratio H2SO4 to HNO3 of 3:1.
基金supported by the National Natural Science Foundation of China (No. 60506015)the Zhejiang Provincial Natural ScienceFoundation of China (No.Y107105).
文摘The comb capacitances fabricated by deep reactive ion etching （RIE） process have high aspect ratio which is usually smaller than 30 ： 1 for the complicated process factors, and the combs are usually not parallel due to the well-known micro-loading effect and other process factors, which restricts the increase of the seismic mass by increasing the thickness of comb to reduce the thermal mechanical noise and the decrease of the gap of the comb capacitances for increasing the sensitive capacitance to reduce the electrical noise. Aiming at the disadvantage of the deep RIE, a novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances is developed. One part of sensing of inertial signal of the micro-accelerometer is by the grid strip capacitances whose overlapping area is variable and which do not have the non-parallel plate＇s effect caused by the deep RIE process. Another part is by the sensing gap alterable capacitances whose gap between combs can be reduced by the actuators. The designed initial gap of the alterable comb capacitances is relatively large to depress the effect of the maximum aspect ratio （30 ： 1） of deep RIE process. The initial gap of the capacitance of the actuator is smaller than the one of the comb capacitances. The difference between the two gaps is the initial gap of the sensitive capacitor. The designed structure depresses greatly the requirement of deep RIE process. The effects of non-parallel combs on the accelerometer are also analyzed. The characteristics of the micro-accelerometer are discussed by field emission microscopy （FEM） tool ANSYS. The tested devices based on slide-film damping effect are fabricated, and the tested quality factor is 514, which shows that grid strip capacitance design can partly improve the resolution and also prove the feasibility of the designed silicon-glass anodically bonding process.
基金supported by the National Natural Science Foundation of China(Nos.61574167,51407181)
文摘Sensitivity analysis methods help to deal with the challenges of process variation in extraction of para- sitic capacitances in an integrated circuit. The dual discrete geometric methods （DGMs）, which have been recently utilized to extract parasitic capacitances, are reviewed. The computation method based on the dual DGMs for sen- sitivities of capacitances with respect to the given process parameters is presented. As the dual DGMs utilize scalar electric potential is unknown, the capacitances are obtained effectively, and then the sensitivities are calculated conveniently.
文摘Supercapacitors are gaining popularity due to their high cycling stability,power density,and fast charge and discharge rates.Researchers are ex-ploring electrode materials,electrolytes,and separat-ors for cost-effective energy storage systems.Ad-vances in materials science have led to the develop-ment of hybrid nanomaterials,such as combining fil-amentous carbon forms with inorganic nanoparticles,to create new charge and energy transfer processes.Notable materials for electrochemical energy-stor-age applications include MXenes,2D transition met-al carbides,and nitrides,carbon black,carbon aerogels,activated carbon,carbon nanotubes,conducting polymers,carbon fibers,and nanofibers,and graphene,because of their thermal,electrical,and mechanical properties.Carbon materials mixed with conducting polymers,ceramics,metal oxides,transition metal oxides,metal hydroxides,transition metal sulfides,trans-ition metal dichalcogenide,metal sulfides,carbides,nitrides,and biomass materials have received widespread attention due to their remarkable performance,eco-friendliness,cost-effectiveness,and renewability.This article explores the development of carbon-based hybrid materials for future supercapacitors,including electric double-layer capacitors,pseudocapacitors,and hy-brid supercapacitors.It investigates the difficulties that influence structural design,manufacturing(electrospinning,hydro-thermal/solvothermal,template-assisted synthesis,electrodeposition,electrospray,3D printing)techniques and the latest car-bon-based hybrid materials research offer practical solutions for producing high-performance,next-generation supercapacitors.
基金supported by the National Natural Science Foundation of China(Grant No.12272369)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0620101).
文摘In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance this sensitivity have predominantly focused on material design and structural optimization,with surface microstructures such as wrinkles,pyramids,and micro-pillars proving effective.Although finite element modeling(FEM)has guided enhancements in CPS sensitivity across various surface designs,a theoretical understanding of sensitivity improvements remains underexplored.This paper employs sinusoidal wavy surfaces as a representative model to analytically elucidate the underlying mechanisms of sensitivity enhancement through contact mechanics.These theoretical insights are corroborated by FEM and experimental validations.Our findings underscore that optimizing material properties,such as Young’s modulus and relative permittivity,alongside adjustments in surface roughness and substrate thickness,can significantly elevate the sensitivity.The optimal performance is achieved when the amplitude-to-wavelength ratio(H/)is about 0.2.These results offer critical insights for designing ultrasensitive CPS devices,paving the way for advancements in sensor technology.
基金supported by the Shenzhen Science and Technology Program(JCYJ20230808105111022,JCYJ20220818095806013)Natural Science Foundation of Guangdong(2023A1515012267)+1 种基金the National Natural Science Foundation of China(22178223)the Royal Society/NSFC cost share program(IEC\NSFC\223372).
文摘Low-electrode capacitive deionization(FCDI)is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters.However,it still suffers from inefficient charge transfer and ion transport kinetics due to weak turbulence and low electric intensity in flow electrodes,both restricted by the current collectors.Herein,a new tip-array current collector(designated as T-CC)was developed to replace the conventional planar current collectors,which intensifies both the charge transfer and ion transport significantly.The effects of tip arrays on flow and electric fields were studied by both computational simulations and electrochemical impedance spectroscopy,which revealed the reduction of ion transport barrier,charge transport barrier and internal resistance.With the voltage increased from 1.0 to 1.5 and 2.0 V,the T-CC-based FCDI system(T-FCDI)exhibited average salt removal rates(ASRR)of 0.18,0.50,and 0.89μmol cm^(-2) min^(-1),respectively,which are 1.82,2.65,and 2.48 folds higher than that of the conventional serpentine current collectors,and 1.48,1.67,and 1.49 folds higher than that of the planar current collectors.Meanwhile,with the solid content in flow electrodes increased from 1 to 5 wt%,the ASRR for T-FCDI increased from 0.29 to 0.50μmol cm^(-2) min^(-1),which are 1.70 and 1.67 folds higher than that of the planar current collectors.Additionally,a salt removal efficiency of 99.89%was achieved with T-FCDI and the charge efficiency remained above 95%after 24 h of operation,thus showing its superior long-term stability.
基金Swiss National Science Foundation through its PRIM A grant(grant No.PR00P2_193111)the NCCR MARVEL,a National Centre of Competence in Researchfunded by the Swiss National Science Foundation。
文摘Electrochemical impedance spectroscopy(EIS)is a widely used technique to monitor the electrical properties of a catalyst under electrocatalytic conditions.Although it is extensively used for research in electrocatalysis,its effectiveness and power have not been fully harnessed to elucidate complex interfacial processes.Herein,we use the frequency dispersion parameter,n,which is extracted from EIS measurements(C_(s)=af^(n+1),-2<n<-1),to describe the dispersion characteristics of capacitance and interfacial properties of Co_(3)O_(4) before the onset of oxygen evolution reaction(OER)in alkaline conditions.We first prove that the n-value is sensitive to the interfacial electronic changes associated with Co redox processes and surface reconstruction.The n-value decreases by increasing the specific/active surface area of the catalysts.We further modify the interfacial properties by changing different components,i.e.,replacing the proton with deuterium,adding ethanol as a new oxidant,and changing the cation in the electrolyte.Intriguingly,the n-value can identify different influences on the interfacial process of proton transfer,the decrease and blocking of oxidized Co species,and the interfacial water structure.We demonstrate that the n-value extracted from EIS measurements is sensitive to the kinetic isotope effect,electrolyte cation,adsorbate surface coverage of oxidized Co species,and the interfacial water structure.Thus,it can be helpful to differentiate the multiple factors affecting the catalyst interface.These findings convey that the frequency dispersion of capacitance is a convenient and useful method to uncover the interfacial properties under electrocatalytic conditions,which helps to advance the understanding of the interfaceactivity relationship.
基金supported financially by National Natural Science Foundation of China(NSFC)(Nos.22478115,22075083)the Programme of Introducing Talents of Discipline to Universities(No.B16017).
文摘The development of high-performance,reproducible carbon(C)-based supercapacitors remains a significant challenge because of limited specific capacitance.Herein,we present a novel strategy for fabricating LaCoO_(x) and cobalt(Co)-doped nanoporous C(LaCoO_(x)/Co@ZNC)through the carbonization of Co/Zn-zeolitic imidazolate framework(ZIF)crystals derived from a PVP-Co/Zn/La precursor.The unique ZIF structure effectively disrupted the graphitic C framework,preserved the Co active sites,and enhanced the electrical conductivity.The synergistic interaction between pyridinic nitrogen and Co ions further promoted redox reactions.In addition,the formation of a hierarchical pore structure through zinc sublimation facili-tated electrolyte diffusion.The resulting LaCoO_(x)/Co@ZNC exhibited exceptional electrochemical performance,delivering a remarkable specific capacitance of 2,789 F/g at 1 A/g and outstanding cycling stability with 92%capacitance retention after 3,750 cycles.Our findings provide the basis for a promising approach to advancing C-based energy storage technologies.
基金financially supported by the National Natural Science Foundation of China(No.U2004210)Application Foundation Frontier Project of Wuhan Science and Technology Program(No.2020010601012199)City University of Hong Kong Strategic Research Grant,Hong Kong,China(No.7005505)。
文摘Vanadium nitride(VN)is a promising pseudocapacitive material due to the high theoretical capacity,rapid redox Faradaic kinetics,and appropriate potential window.Although VN shows large pseudocapacitance in alkaline electrolytes,the electrochemical instability and capacity degradation of VN electrode materials present significant challenges for practical applications.Herein,the capacitance decay mechanism of VN is investigated and a simple strategy to improve cycling stability of VN supercapacitor electrodes is proposed by introducing VO_(4)^(3-)anion in KOH electrolytes.Our results show that the VN electrode is electrochemical stabilization between-1.0and-0.4 V(vs.Hg/Hg O reference electrode)in 1.0 MKOH electrolyte,but demonstrates irreversible oxidation and fast capacitance decay in the potential range of-0.4 to0 V.In situ electrochemical measurements reveal that the capacitance decay of VN from-0.4 to 0 V is ascribed to the irreversible oxidation of vanadium(V)of N–V–O species by oxygen(O)of OH^(-).The as-generated oxidization species are subsequently dissolved into KOH electrolytes,thereby undermining the electrochemical stability of VN.However,this irreversible oxidation process could be hindered by introducing VO_(4)^(3-)in KOH electrolytes.A high volumetric specific capacitance of671.9 F.cm^(-3)(1 A.cm^(-3))and excellent cycling stability(120.3%over 1000 cycles)are achieved for VN nanorod electrode in KOH electrolytes containing VO_(4)^(3-).This study not only elucidates the failure mechanism of VN supercapacitor electrodes in alkaline electrolytes,but also provides new insights into enhancing pseudocapacitive energy storage of VN-based electrode materials.
基金supported by the National Natural Science Foundation of China(No.51902134)Zhejiang Public Welfare Technology Application Research Program(No.LGJ22B040001)+1 种基金the Innovation Jiaxing Elite Leading Plan 2020,Jiaxing Public Welfare Technology Application Research Program(No.2023AY11051)the Fundamental Research Funds for the Jiaxing University(No.CD70519019,No.CDN70518005,No.CD70623018).
文摘Thick and highly conductive poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate films with ideal porous structure are fulfilling as electrodes for supercapacitors.However,the homogeneous micro-structure without the aid of templates or composite presents a significant obstacle,due to the intrinsic softness of the dominant PSS component.In this study,we have successfully developed a porous configuration by employing a solvothermal approach with ethylene glycol(EG)as the solvent.The synergistic action of elevated pressure and temperature was crucial in prompting EG to tailor the microstructure of the PEDOT:PSS films by removing non-conductive PSS chains and improving PEDOT crystallinity,and the formation of a porous network.The resulting porous PEDOT:PSS films exhibited a high conductivity of 1644 S cm^(-1)and achieved a volumetric capacitance record of 270 F cm^(-3),markedly exceeding previous records.The flexible all-solid-state supercapacitor assembled by the films had an outstanding volumetric capacitance of 97.8 F cm^(-3)and an energy density of 8.7 mWh cm^(-3),which is best one for pure PEDOT:PSS-based supercapacitors.Grazing-incidence wide-angle X-ray scattering,X-ray photoelectron spectroscopy,and other characterizations were carried out to characterize the structure evolution.This work offers an effective novel method for conducting polymer morphology control and promotes PEDOT:PSS applications in energy storage field.
基金National Key Research and Development Program of China(2021YFA1501302)the National Natural Science Foundation of China(22121004,22122808)+1 种基金the Haihe Laboratory of Sustainable Chemical Transformations and the Program of Introducing Talents of Discipline to Universities(BP0618007)for financial supportsupported by the XPLORER PRIZE.
文摘Noise is inevitable in electrical capacitance tomography(ECT)measurements.This paper describes the influence of noise on ECT performance for measuring gas-solids fluidized bed characteristics.The noise distribution is approximated by the Gaussian distribution and added to experimental capacitance data with various intensities.The equivalent signal strength(Ф)that equals the signal-to-noise ratio of packed beds is used to evaluate noise levels.Results show that the Pearson correlation coefficient,which indicates the similarity of solids fraction distributions over pixels,increases with Ф,and reconstructed images are more deteriorated at lower Ф.Nevertheless,relative errors for average solids fraction and bubble size in each frame are less sensitive to noise,attributed to noise compromise caused by the process of pixel values.These findings provide useful guidance for assessing the accuracy of ECT measurements of multiphase flows.
基金supported by FAST(19FAYORA14)of the Canadian Space Agency,Discovery Grant(RGPIN2024-06290)supported by CREATE grant(555425-2021)&Discovery grant(RGPIN-2024-06290)of the Natural Sciences and Engineering Research Council of Canada.
文摘This review explores the current state and future prospects of tactile sensing technologies in space robotics,addressing the unique challenges posed by harsh space environments such as extreme temperatures,radiation,microgravity,and vacuum conditions,which necessitate specialized sensor designs.We provide a detailed analysis of four primary types of tactile sensors:resistive,capacitive,piezoelectric,and optical,evaluating their operating principles,advantages,limitations,and specific applications in space exploration.Recent advancements in materials science,including the development of radiation-hardened components and flexible sensor materials,are discussed alongside innovations in sensor design and integration techniques that enhance performance and durability under space conditions.Through case studies of various space robotic systems,such as Mars rovers,robotic arms like Canadarm,humanoid robots like Robonaut,and specialized robots like Astrobee and LEMUR 3,this review highlights the crucial role of tactile sensing in enabling precise manipulation,environmental interaction,and autonomous operations in space.Moreover,it synthesizes current research and applications to underscore the transformative impact of tactile sensing technologies on space robotics and highlights their pivotal role in expanding human presence and scientific understanding in space,offering strategic insights and recommendations to guide future research and development in this critical field.
基金the National Natural Science Foundation of China(Grant No.52374051)the Joint Fund for Enterprise Innovation and Development of NSFC(Grant No.U24B2037).
文摘During oilfield development,a comprehensive model for assessing inter-well connectivity and connected volume within reservoirs is crucial.Traditional capacitance(TC)models,widely used in inter-well data analysis,face challenges when dealing with rapidly changing reservoir conditions over time.Additionally,TC models struggle with complex,random noise primarily caused by measurement errors in production and injection rates.To address these challenges,this study introduces a dynamic capacitance(SV-DC)model based on state variables.By integrating the extended Kalman filter(EKF)algorithm,the SV-DC model provides more flexible predictions of inter-well connectivity and time-lag efficiency compared to the TC model.The robustness of the SV-DC model is verified by comparing relative errors between preset and calculated values through Monte Carlo simulations.Sensitivity analysis was performed to compare the model performance with the benchmark,using the Qinhuangdao Oilfield as a case study.The results show that the SV-DC model accurately predicts water breakthrough times.Increases in the liquid production index and water cut in two typical wells indicate the development time of ineffective circulation channels,further confirming the accuracy and reliability of the model.The SV-DC model offers significant advantages in addressing complex,dynamic oilfield production scenarios and serves as a valuable tool for the efficient and precise planning and management of future oilfield developments.
基金financially supported by the Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)the National Natural Science Foundation of China(52374423)+1 种基金the Major Science and Technology Programs of Yunnan Province(202302AB080016)the Hunan Provincial Natural Science Youth Fund(2024JJ6726)。
文摘The capacitive deionization(CDI)performance of silver(Ag)electrodes is limited by electrochemical failure induced by volumetric expansion.While carbon encapsulation and Ag size control mitigate stress concentration and pulverization,achieving precise size control,suppression of aggregation,and uniform dispersion of Ag nanoparticles remains challenging.Herein,the metal-organic frameworks(MOF)-assisted pyrolysis-galvanic replacement method was employed to construct ultrafine Ag particles uniformly anchored within a three-dimensional(3D)-ordered porous carbon skeleton composite(3D Ag@NC).By utilizing the potential difference between the elements,spontaneous replacement reactions occur,effectively preventing particle agglomeration usually caused by high-temperature reduction.The in situ constructed 3D porous carbon skeleton not only promotes electron transfer and electrolyte penetration but also mitigates the volume expansion of Ag particles during electrochemical cycling.Consequently,3D Ag@NC demonstrates outstanding dechlorination performance(105.29 mg g^(-1)),high charge efficiency(0.95),and exceptional cycling stability(84.12% after 100 cycles).This galvanic replacement strategy offers valuable insights into the fabrication of other small-sized,highly dispersed metal electrode materials.
基金supported by the National Science Foundation of China(No.21606191)the Natural Science Foundation of Shandong Province(No.ZR2020ME024).
文摘As a new electrochemical technology,capacitive deionization(CDI)has been increasingly applied in environmental water treatment and seawater desalination.In this study,functional groups modified porous hollow carbon(HC)were synthesized as CDI electrode material for removing Na^(+)and Cl^(−)in salty water.Results showed that the average diameter of HC was approximately 180 nm,and the infrared spectrum showed that its surface was successfully modified with sulfonic and amino groups,respectively.The sulfonic acid functionalized HC(HC-S)showed better electrochemical and desalting performance than the amino-functionalized HC(HC–N),with a maximum Faradic capacity of 287.4 F/g and an adsorptive capacity of 112.97 mg/g for NaCl.Additionally,92.63%capacity retention after 100 adsorption/desorption cycles demonstrates the excellent stability of HC-S.The main findings prove that HC-S is viable as an electrodematerial for desalination by high-performance CDI applications.
基金supported by the National Key R&D Program of China(Grant Nos.2023YFC3009900)National Natural Science Foundation of China(Grant Nos.61904116)+1 种基金Natural Science Foundation of Jiangsu Province(Grant Nos.BK20211029)the young scientific talent lifting project of Jiangsu Association for Science and Technology(Grant Nos.JSTJ-2023-018).
文摘Hybrid capacitive deionization(HCDI)shows promise for desalinating brackish and saline water by utilizing the pseudocapacitive properties of faradaic electrodes.Organic materials,with their low environmental impact and adaptable structures,are attractive for this application.However,their scarcity of active sites and tendency to dissolve in water-based solutions remain significant challenges.Herein,we synthesized a polynaphthalenequinoneimine(PCON)polymer with stable long-range ordered framework and rough three-dimensional floral surface morphology,along with high-density active sites provided by C=O and C=N functional groups,enabling efficient redox reactions and achieving a high Na^(+)capture capability.The synthesized PCON polymer showcases outstanding electroadsorption characteristics and notable structural robustness,attaining an impressive specific capacitance of 500.45 F g^(-1) at 1 A g^(-1) and maintaining 86.1%of its original capacitance following 5000 charge–discharge cycles.Benefiting from the superior pseudocapacitive properties of the PCON polymer,we have developed an HCDI system that not only exhibits exceptional salt removal capacity of 100.8 mg g^(-1) and a remarkable rapid average removal rate of 3.36 mg g^(-1) min-1 but also maintains 97%of its initial desalination capacity after 50 cycles,thereby distinguishing itself in the field of state-ofthe-art desalination technologies with its comprehensive performance that significantly surpasses reported organic capacitive deionization materials.Prospectively,the synthesis paradigm of the double active-sites PCON polymer may be extrapolated to other organic electrodes,heralding new avenues for the design of high-performance desalination systems.
基金the Professional Technical Service Platform of Shanghai Science and Technology Commission(No.19DZ2291103)。
文摘A novel characterization method for full-matrix constants of PzT-8 piezoceramics based on local electrodes excitation using one sample is proposed to avoid resonant peaks missing and overlapping in the inversion process of resonant ultrasound spectroscopy technology.Elastic matrix,which is sensitive to the resonance spectrum,is obtained by resonant ultrasound spectroscopy.Piezoelectric and dielectric matrices,which are sensitive to the capacitance of driving electrodes,are determined by capacitance inversion.The initial values of elastic constants are deviated by 30%to validate the reliability of this method.The relative errors between measured and inversed values of resonant frequencies are less than 1%and the relative errors of the capacitance are mostly less than 5%.The work has extensive applications in piezoelectric materials characterization.
文摘Capacitive voltage transformers (CVTs) are essential in high-voltage systems. An accurate error assessment is crucial for precise energy metering. However, tracking real-time quantitative changes in capacitive voltage transformer errors, particularly minor variations in multi-channel setups, remains challenging. This paper proposes a method for online error tracking of multi-channel capacitive voltage transformers using a Co-Prediction Matrix. The approach leverages the strong correlation between in-phase channels, particularly the invariance of the signal proportions among them. By establishing a co-prediction matrix based on these proportional relationships, The influence of voltage changes on the primary measurements is mitigated. Analyzing the relationships between the co-prediction matrices over time allows for inferring true measurement errors. Experimental validation with real-world data confirms the effectiveness of the method, demonstrating its capability to continuously track capacitive voltage transformer measurement errors online with precision over extended durations.
