Lead-free relaxor ceramics(1−x)K_(0.5)Na_(0.5)NbO_(3)−xBi(Mn_(0.5)Ni_(0.5))O_(3)((1−x)KNN-xBMN)with considerable charge-discharge characteristics and energy storage properties were prepared by a solid state method.Rem...Lead-free relaxor ceramics(1−x)K_(0.5)Na_(0.5)NbO_(3)−xBi(Mn_(0.5)Ni_(0.5))O_(3)((1−x)KNN-xBMN)with considerable charge-discharge characteristics and energy storage properties were prepared by a solid state method.Remarkable,a BMN doping level of 0.04,0.96KNN-0.04BMN ceramic obtained good energy storage performance with acceptable energy storage density Wrec of 1.826 J/cm^(3) and energy storage efficiencyηof 77.4%,as well as good frequency stability(1-500 Hz)and fatigue resistance(1-5000 cycles).Meanwhile,a satisfactory charge-discharge performance with power density PD~98.90 MW/cm^(3),discharge time t0.9<70 ns and temperature stability(30-180°C)was obtained in 0.96KNN-0.04BMN ceramic.The small grain size(~150 nm)and the high polarizability of Bi3+are directly related to its good energy storage capacity.This work proposes a feasible approach for lead-free KNN-based ceramics to achieve high-energy storage and ultra-fast charge-discharge performance as well as candidate materials for the application of advanced high-temperature pulse capacitors.展开更多
In Senegal, the Diamniadio, Sebikhotane and Bargny sector contains clay soils that are problematic for construction. In order to have more information on the behavior of the clay soils of Diamniadio, free swelling tes...In Senegal, the Diamniadio, Sebikhotane and Bargny sector contains clay soils that are problematic for construction. In order to have more information on the behavior of the clay soils of Diamniadio, free swelling tests followed by load-discharge cycles were carried out according to standard NF P 94-090-1. These tests were carried out using an Oedometric device on the three samples from the study site (sandy clays with calcareous concretion, marls with crumbs and laminated marls with attapulgite) to apprehend their swelling aspects in saturated conditions. For the free swelling test, a determination of the different swelling phases will be carried out followed by a comparison of the rate of evolution of the phases for the three samples from the site. In the same vein, the compressibility characteristics of the samples will also be provided from load-unload Oedometric tests. Thereafter, we proceed to a comparison of the void index at the initial state of the samples after two charge-discharge cycles and the influence of the cycles on the reorganization of the internal structure of the samples. These studies will provide more information on the swelling behavior of Diamniadio soils in the presence of water.展开更多
This study presents a centralized control scheme that coordinates parallel operations of power conditioning system(PCS)for the grid interactions of electric vehicles(EVs)in EV charge-discharge and storage integration ...This study presents a centralized control scheme that coordinates parallel operations of power conditioning system(PCS)for the grid interactions of electric vehicles(EVs)in EV charge-discharge and storage integration station.Key issues for the control and operation of PCS under various operation modes are discussed,including vehicle to grid(V2G)mode,stand-alone mode and seamless transfer mode.The intelligent multi-mode charge-discharge method is utilized for the V2G mode,and the parallel control method based on communication network is adopted for the standalone mode.In addition,a novel seamless transfer strategy is proposed,which is able to implement PCS transition between V2G mode and stand-alone mode.The detailed process of the seamless transfer between the two modes is illustrated.Experimental results are presented to show the performance and feasibility of this strategy.展开更多
In recent years,the rapid charge-discharge property of super capacitors based on metal-organic frameworks(MOFs)has seen excellent applications in energy storage equipment.However,the purposeful design of high-performa...In recent years,the rapid charge-discharge property of super capacitors based on metal-organic frameworks(MOFs)has seen excellent applications in energy storage equipment.However,the purposeful design of high-performance electrodes for MOFderived super capacitors is still an urgent problem that needs to be solved.Herein,we rationally design and prepare three MOFs with the same crystal configuration and controllable functional groups.Through the combination of rigorous experiment and calculation,we have verified the effects of the specific surface area of the electrode material as well as the binding energy between the electrode material and the electrolyte ions on the performance of the super capacitor.This work not only extends the application of MOFs,but also provides a model-material platform for the study of charge–discharge behavior of MOF-based super capacitors,creating a way of thinking for the selection and design of MOF materials for energy storage applications.展开更多
With the increasing demand for clean renewable energy and electric cars,people have put forward higher requirement for the energy storage system.One of the most successful lithium-ion batteries with a cathode combinat...With the increasing demand for clean renewable energy and electric cars,people have put forward higher requirement for the energy storage system.One of the most successful lithium-ion batteries with a cathode combination of lithium nickel manganese cobalt oxide(also called NCM lithium-ion battery),has been playing an increasingly important role.So far,numerous research has been done on the fabrication of cathode material with optimization of its composition,design,and assembly of the battery system in order to improve the energy storage performance.However,most of the previous studies were conducted based on relatively short cycling time of testing,with limited charge-discharge cycles of no more than 1000.Thus the conclusions were insufficient to be applied in the practical working condition.In this work,by using the developed NCM523 lithium-ion batteries,we have performed a series of ultra-long cycling tests on the individual cell and its module,with a comprehensive study on the relationship between the retained capacity after long cycling time and the depth of discharge(DOD),charge-discharge rate and operating temperature.Optimization of the charge-discharge strategies on a single cell and the whole module was also made to effectively improve the overall energy storage efficiency.This experimental study offers a guideline for the efficient use of similar types of lithium-ion batteries in the practical working condition.The developed batteries together with the optimized charge-discharge strategy proposed here are promising to meet the requirements for applications of stationary energy storage and electric cars.展开更多
Conducting polyaniline (PANI) powder was well mixed with graphite and acetylene black to obtain the optimum conductivity and porosity. The mixed powder was compressed into a pellet for cathode. Zinc powder was mixed w...Conducting polyaniline (PANI) powder was well mixed with graphite and acetylene black to obtain the optimum conductivity and porosity. The mixed powder was compressed into a pellet for cathode. Zinc powder was mixed with some metal powder, and compressed into a pellet used as the anode. The electrolyte comprised ZnCl2, NH4Cl, Triton-X100 and PVA at pH 3. The battery has an open-circuit voltage of 1.44 V. The battery underwent charge-discharge cycle with a constant current density of 3 mA·cm-2, within the voltage range of 0.40-1.68 V. It is found that the capacity of the battery is related to the charge-discharge cycles, the maximum capacity is 67.9 mAh·g-1, and Coulombic efficiency is between 95% and 100%. The battery stability was also investigated after 78 d of standing without use. It is found that the battery experiences a self-discharge of less than 0.29% per day.展开更多
So far,a clear understanding about the relationship of variable energy band structure with the corresponding charge-discharge process of energy storage materials is still lacking.Here,using optical spectroscopy(red-gr...So far,a clear understanding about the relationship of variable energy band structure with the corresponding charge-discharge process of energy storage materials is still lacking.Here,using optical spectroscopy(red-green-blue(RGB)value,reflectivity,transmittance,UV-vis,XPS,UPS)to studyα-Co(OH)_(2) electrode working in KOH electrolyte as the research object,we provide direct experimental evidence that:(1)The intercalation of OH-ions will reduce the valence/conduction band(VB and CB)and band gap energy(Eg)values;(2)The deintercalation of OH-ions corresponds with the reversion of VB,CB and E_(g) to the initial values;(3)The color of Co(OH)_(2) electrode also exhibit regular variations in RGB value during the charge-discharge process.展开更多
Dielectric capacitors with high capacitive energy storage are urgently needed to meet the growing demand for high-performance energy storage devices.Herein,a novel lead-free Sr_(5)BiTi_(3)Nb_(7)O_(30)(SBTN)tungsten br...Dielectric capacitors with high capacitive energy storage are urgently needed to meet the growing demand for high-performance energy storage devices.Herein,a novel lead-free Sr_(5)BiTi_(3)Nb_(7)O_(30)(SBTN)tungsten bronze relaxor ferroelectric ceramic is prepared and explored for potential energy storage applications.A high recoverable energy density Wrec(~3.72 J/cm^(3))and ultrahigh efficiencyη(~94.2%)at 380 kV/cm are achieved simultaneously.Both Wrec andηexhibit superior stabilities against temperature(30-140°C),cycles(100-105)and frequency(1-500 Hz).In addition,a high current density of 796 A/cm^(2) and a large power density of 71.7 MW/cm^(3) are achieved,together with good thermal endurance and fatigue resistance.These results demonstrate that the obtained SBTN ceramic can be deemed as the promising candidates for dielectric capacitor applications.展开更多
BaTiO_(3)(BT)has attracted extensive attention among advanced lead-free ferroelectric materials due to its unique dielectric and ferroelectric properties.However,the enormous remanent polarization and coercive field s...BaTiO_(3)(BT)has attracted extensive attention among advanced lead-free ferroelectric materials due to its unique dielectric and ferroelectric properties.However,the enormous remanent polarization and coercive field severely impede the improvement of its energy storage capabilities.Here,the BaTiO_(3)e-Bi(Zn_(0.5)Hf_(0.5))O_(3)(BT-BZH)ceramics with high breakdown field strength and remarkable relaxation characteristics can be obtained by introducing the composite component BZH in BT to regulate the phase structure and grain size of the ceramics.The findings demonstrate that the improvement of energy storage performance is related to the increase of relaxation behavior.A large energy storage density(Wrec~3.62 J/cm^(3))along with superior energy storage efficiency(h~88.5%)is achieved in 0.88BT-0.12BZH relaxor ceramics only at 240 kV/cm.In addition,the sample suggests superior thermal stability and frequency stability within 25e115℃and 1e500 Hz,respectively.Furthermore,the outstanding chargedischarge properties with an ultrafast discharge time(100 ns),large discharged energy density(1.2 J/cm^(3)),impressive current density(519.4 A/cm^(2))and power density(31.1 MW/cm^(3))under the electric field of 120 kV/cm are achieved in studied ceramics.The excellent energy storage performance of BT-BZH ceramics provides a promising platform for the application of lead-free energy-storage materials.展开更多
In the last few decades,dielectric capacitors have gotten a lot of attention because they can store more power and charge and discharge very quickly.But it has a low energy-storage density(Wrec),efficiency(h),and temp...In the last few decades,dielectric capacitors have gotten a lot of attention because they can store more power and charge and discharge very quickly.But it has a low energy-storage density(Wrec),efficiency(h),and temperature stability.By adding Pb(Mg1/3Nb2/3)O3(PMN)and(Bi0$1Sr0.85)TiO3(BST)to a nonstoichiometric(Bi0$51Na0.5)TiO3(BNT)matrix,the goal is to change the phase transition properties and make the material more relaxor ferroelectric(RFE)by lowering the remnant polarization Pr and keeping the maximum polarization Pmax.A viscous polymer process(VPP)is used to improve the electric breakdown strength,which is also a key part of being able to store energy.By working together,ceramics with the formula 0.79[0.85BNT-0.15PMN]-0.21BST(BP-0.21BST)are made.The phase structure has been changed from a rhombohedral phase to a rhombohedral-tetragonal coexisted phase.This is beneficial for RFE properties and gives a Wrec of 6.45 J/cm^(3) and a h of 90%at 400 kV/cm.Also,the energy-storage property is very temperature stable between 30 and 150C.These results show that process optimization and composition design can be used to improve the energy storage properties,and that the dielectric ceramic materials made can be used in high-powder pulse dielectric capacitors.展开更多
To improve the low-temperature charge-discharge performance of lithium-ion battery,low-temperature experiments of the charge-discharge characteristics of 35 Ah high-power lithium-ion batteries have been conducted,and ...To improve the low-temperature charge-discharge performance of lithium-ion battery,low-temperature experiments of the charge-discharge characteristics of 35 Ah high-power lithium-ion batteries have been conducted,and the wide-line metal film method for heating batteries is presented.At-40℃,heating and charge-discharge experiments have been performed on the battery pack.The results indicate the charge-discharge performance is substantially worse in cold climates,and can be significantly improved by heating the battery pack with a wide-line metal film.Pulse charge-discharge experiments show that at-40℃ambient temperature,the heated battery pack can charge or discharge at high current and offer almost80%power.展开更多
Layered Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08-x)Al_xO_2(0 ≤ x ≤(0.08)) cathode materials were successfully synthesized by a sol-gel method. X-ray diffraction and the refinement data indicate that all materials have typ...Layered Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08-x)Al_xO_2(0 ≤ x ≤(0.08)) cathode materials were successfully synthesized by a sol-gel method. X-ray diffraction and the refinement data indicate that all materials have typical α-NaFeO_2 structure with R-3m space group, and the a-axis has almost no change, but there is a slight decrease in the c lattice parameter as well as the cell volume. Scanning electron microscopy and high resolution transmission electron microscopy prove that all the samples have uniform particle size of about 200–300 nm and smooth surface. The energy-dispersive X-ray spectroscopy mapping shows that aluminum has been homogeneously doped in the Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08)O_2 cathode material. The cyclic voltammetry and electrochemical impedance spectroscopy reveal that appropriate Al-doping contributes to the reversible lithium-ion insertion and extraction, and then reduces the electrochemical polarization and charge transfer resistance. Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08-x)Al_xO_2(x = 0.05)shows the lowest charge transfer resistance and the highest lithium-ion diffusion coefficient among all the samples. The Li-rich electrodes with low-level Al doping shows a much higher discharge capacity than the pristine one, especially the Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08-x)AlxO_2(x = 0.05) sample, which exhibits greater rate capacity and better fast charge-discharge performance than the other samples. Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08-x)Al_xO_2(x = 0.05) also exhibits higher discharge capacity than the pristine one at each cycle at 55°C. These results clearly indicate that the high rate capacity together with a good high rate cycling performance and high-temperature performance of the low-Co Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08-x)Al_xO_2(x=0.05) is a promising alternative to next-generation lithium-ion batteries.展开更多
Layered Li-rich Mn-based oxides are promising cathode materials for Li-ion batteries due to their high capacity and high operation voltage.However,their commercial applications are hindered by irreversible capacity lo...Layered Li-rich Mn-based oxides are promising cathode materials for Li-ion batteries due to their high capacity and high operation voltage.However,their commercial applications are hindered by irreversible capacity loss in the first charge-discharge process,voltage decay during cycling,inefficient cyclability and rate capability.Many attempts have been performed to solve such issues,including the mechanism study and strategies to improve the electrochemical performance.This article provides a brief review and future perspective on the main challenges of the high-capacity Li-rich Mn-based cathodes for Li-ion batteries.展开更多
Increasing concern has been focused on the search for ecofriendly dielectric ceramics to meet the extensive demands of pulsed capacitors.Due to the advantages of high-energy storage density,efficiency,and excellent te...Increasing concern has been focused on the search for ecofriendly dielectric ceramics to meet the extensive demands of pulsed capacitors.Due to the advantages of high-energy storage density,efficiency,and excellent temperature stability,optimization of energy storage performance in dielectric ceramics has been a goal in the past decades.This review summarizes the recently reported progress in energy storage properties of typical perovskite-type lead-free ceramics.The advantages and shortcomings in the various kinds of ceramics are discussed.Finally,future prospects are presented to provide some guidelines for the exploration of new materials.展开更多
Environmentally friendly lead-free ceramics capacitors,with outstanding power density,rapid charging/discharging rate,and superior stability,have been receiving increasing attention of late for their ability to meet t...Environmentally friendly lead-free ceramics capacitors,with outstanding power density,rapid charging/discharging rate,and superior stability,have been receiving increasing attention of late for their ability to meet the critical requirements of pulsed power devices in low-consumption systems.However,the relatively low energy storage capability must be urgently overcome.Herein,this work reports on leadfree SrTi_(0.875)Nb_(0.1)O_(3)(STN)replacement of(Bi_(0.47)La_(0.03)Na_(0.5))_(0.94)Ba_(0.06)TiO_(3)(BLNBT)ferroelectric ceramics with excellent energy storage performance.Improving relaxor behaviour and breakdown strength(Eb),decreasing grain size,and mitigating large polarization difference are conductive to the enhancement of comprehensive energy storage performances.The phase-field simulation methods are further analysized evolution process of electrical tree in the experimental breakdown.In particular,the 0.70BLNBT-0.30STN ceramic exhibit a large discharged energy density of 4.2 J/cm^(3) with an efficiency of 89.3%at room temperature under electric field of 380 kV/cm.Additionally,for practical applications,the BLNBT-based ceramics achieve a high power density(~62.3 MW/cm^(3))and fast discharged time(~148.8 ns)over broad temperature range(20-200℃).Therefore,this work can provide a simple and effective guideline paradigm for acquiring high-performance dielectric materials in low-consumption systems operating in a wide range of temperatures and long-term operations.展开更多
Lead-free ceramic capacitors have the application prospect in the dielectric pulse power system due to the advantages of large dielectric constant,lower dielectric loss and good temperature stability.Never-theless,mos...Lead-free ceramic capacitors have the application prospect in the dielectric pulse power system due to the advantages of large dielectric constant,lower dielectric loss and good temperature stability.Never-theless,most reported dielectric ceramics have limitation of realizing large energy storage density(W_(rec))and high energy storage efficiency(h)simultaneously due to the low breakdown electric field(E_(b)),low maximum polarization and large remanent polarization(P_(r)).These issues above can be settled by raising the bulk resistivity of dielectric ceramics and optimizing domain structure.Therefore,we designed a new system by doping(Bi_(0.5)Na_(0.5))_(0.7)Sr_(0.3)TiO_(3) into 0.9NaNbO_(3)-0.1Bi(Ni_(0.5)Zr_(0.5))O_(3) ceramics,which simulta-neously obtained a higher bulk resistivity by decreasing the grain size and achieved a smaller P_(r) by optimizing domain structure,thus the better E_(b) of 530 kV/cm and W_(rec) of 6.43 J/cm^(3) were achieved,h was improved from 34%to 82%.Besides,the 0.4BNST ceramics show excellent temperature,frequency and fatigue stability under the conditions of 20-180℃,1-100 Hz and 104 cycles,respectively.Mean-while,superior power density(P_(D)=107 MW/cm^(3)),large current density(C_(D)=1070 A/cm^(2))and discharge speed(1.025 m s)were achieved in 0.4BNST ceramic.Finally,the charge-discharge performance displayed good temperature stability in the temperature range of 30℃-180℃.The above results indicated that the ceramics have potential practical value in the field of energy storage capacitor.展开更多
Designing dielectric materials with the tremendous energy storage density is fundamentally important for developing pulse power capacitors.An effective approach was proposed to favorably modify the dielectric energy s...Designing dielectric materials with the tremendous energy storage density is fundamentally important for developing pulse power capacitors.An effective approach was proposed to favorably modify the dielectric energy storage properties(ESP)of Bi_(0.5)Na_(0.5)TiO_(3) ceramics using CaTiO_(3) incorporation.The dielectric breakdown strength was effectively enhanced,and simultaneously the relaxor behavior was optimized to lower the remnant polarization,which is resulted from the decreased grains size with the introduction of Ca^(2+)ion.Remarkably,at a CaTiO_(3) doping level of 0.2,a 0.8Bi_(0.5)Na_(0.5)TiO_(3)-0.2CaTiO_(3)(0.8BNT-0.2CT)ceramic obtained both high energy storage density(Wtotal)of~1.38 J/cm^(3) together with excellent efficiency(h)of~91.3%.Furthermore,an ultrafast discharge response speed(t0:9)~94 ns was achieved in 0.8BNT-0.2CT ceramic,as well as tremendous current density(C_(D)~1520 A/cm2)and power density(P_(D)~115 MW/cm^(3)).This study not only revealed the superior ESP mechanism as regards Bi_(0.5)Na_(0.5)TiO_(3) based ceramics but also provided candidate materials in pulse power capacitor devices.展开更多
Polyfluorene (PF) film has been successfully electropolymerized at lower potential (0.91 V vs.Ag/AgCl) in the mixed electrolyte of boron trifluoride diethyl etherate and trifluoroacetic acid.The PF film is characteriz...Polyfluorene (PF) film has been successfully electropolymerized at lower potential (0.91 V vs.Ag/AgCl) in the mixed electrolyte of boron trifluoride diethyl etherate and trifluoroacetic acid.The PF film is characterized to have about 10 repeat units and no presence of ketonic defect site.UV-vis and photoluminescent spectral studies indicate that the PF film is blue light emitting.From cyclic voltammetry and galvanostatic charge-discharge tests in 1 M lithium perchlorate/acetonitrile electrolyte,the polyfluorene/activated carbon electrode shows a specific capacitance of 227.1 F g-1 (per active layer mass) and reversible redox reaction at the potential of 1.4 V in a three electrode configuration.An asymmetric electrochemical capacitor based on this composite electrode and activated carbon electrode exhibits a specific energy of 14.7 Wh kg-1 (per active layer mass).These results indicate that electrochemically prepared polyfluorene could be used as energy storage component for electrochemical application.展开更多
Despite the promising characteristics of Dielectric Elastomel Actuator(DEA)as a practical soft actuator,the need of high voltage for its operation prevents the successful fabrication of a practical DEA,that is,the hig...Despite the promising characteristics of Dielectric Elastomel Actuator(DEA)as a practical soft actuator,the need of high voltage for its operation prevents the successful fabrication of a practical DEA,that is,the high voltage generation takes a bulky and costly power supply.Induction of complex shape change motion of DEA such as oscillatory shape change takes even a more bulky and costly multipurpose power supply.It is a serious practical issue to be overcome.In our latest study,however,we could build a simple DEA system which exhibited a relatively complex and autonomous oscillatory shape change merely under a constant voltage,though the voltage needed was high.This successful outcome must broaden the potential usefulness of DEA as a practical soft actuator.展开更多
One-dimensional manganese oxide nanobelt bundles with birnessite-type structure have been synthesized by a hydrothermal process in a NaOH solution employing K-type layered manganese oxide as a precursor. The obtained ...One-dimensional manganese oxide nanobelt bundles with birnessite-type structure have been synthesized by a hydrothermal process in a NaOH solution employing K-type layered manganese oxide as a precursor. The obtained manganese oxide nanobelt bundles exhibit excellent discharge properties and cycle stability. The initial capacity is 376 mAh-g-1 and the reversible capacity of 243 mAhog-1 is maintained after the 50th cycle at a current density of 20 mA·g-t. Meanwhile, the manganese oxide nanobelt bundles show an excellent cycle performance even if at relative high current density.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)(Grant No.52272119,51872177)the Natural Science Basic Research Plan in the Shaanxi Province of China(Grant No.2021ZDLSF06-03,2021JM-201)+1 种基金the Fundamental Research Funds for the Central Universities(Program No.GK202002014)the Fondamental Innovation Project in School of Materials Science and Engineering(SNNU).
文摘Lead-free relaxor ceramics(1−x)K_(0.5)Na_(0.5)NbO_(3)−xBi(Mn_(0.5)Ni_(0.5))O_(3)((1−x)KNN-xBMN)with considerable charge-discharge characteristics and energy storage properties were prepared by a solid state method.Remarkable,a BMN doping level of 0.04,0.96KNN-0.04BMN ceramic obtained good energy storage performance with acceptable energy storage density Wrec of 1.826 J/cm^(3) and energy storage efficiencyηof 77.4%,as well as good frequency stability(1-500 Hz)and fatigue resistance(1-5000 cycles).Meanwhile,a satisfactory charge-discharge performance with power density PD~98.90 MW/cm^(3),discharge time t0.9<70 ns and temperature stability(30-180°C)was obtained in 0.96KNN-0.04BMN ceramic.The small grain size(~150 nm)and the high polarizability of Bi3+are directly related to its good energy storage capacity.This work proposes a feasible approach for lead-free KNN-based ceramics to achieve high-energy storage and ultra-fast charge-discharge performance as well as candidate materials for the application of advanced high-temperature pulse capacitors.
文摘In Senegal, the Diamniadio, Sebikhotane and Bargny sector contains clay soils that are problematic for construction. In order to have more information on the behavior of the clay soils of Diamniadio, free swelling tests followed by load-discharge cycles were carried out according to standard NF P 94-090-1. These tests were carried out using an Oedometric device on the three samples from the study site (sandy clays with calcareous concretion, marls with crumbs and laminated marls with attapulgite) to apprehend their swelling aspects in saturated conditions. For the free swelling test, a determination of the different swelling phases will be carried out followed by a comparison of the rate of evolution of the phases for the three samples from the site. In the same vein, the compressibility characteristics of the samples will also be provided from load-unload Oedometric tests. Thereafter, we proceed to a comparison of the void index at the initial state of the samples after two charge-discharge cycles and the influence of the cycles on the reorganization of the internal structure of the samples. These studies will provide more information on the swelling behavior of Diamniadio soils in the presence of water.
基金This work was supported in part by the National Natural science Foundation of China under Grant 51361130150 and Grant 51477067in part by the Fundamental Research Funds for the Central Universities under Grant 2014QN219.
文摘This study presents a centralized control scheme that coordinates parallel operations of power conditioning system(PCS)for the grid interactions of electric vehicles(EVs)in EV charge-discharge and storage integration station.Key issues for the control and operation of PCS under various operation modes are discussed,including vehicle to grid(V2G)mode,stand-alone mode and seamless transfer mode.The intelligent multi-mode charge-discharge method is utilized for the V2G mode,and the parallel control method based on communication network is adopted for the standalone mode.In addition,a novel seamless transfer strategy is proposed,which is able to implement PCS transition between V2G mode and stand-alone mode.The detailed process of the seamless transfer between the two modes is illustrated.Experimental results are presented to show the performance and feasibility of this strategy.
基金supported by the National Natural Science Foundation of China(Nos.22005273 and 21825106).
文摘In recent years,the rapid charge-discharge property of super capacitors based on metal-organic frameworks(MOFs)has seen excellent applications in energy storage equipment.However,the purposeful design of high-performance electrodes for MOFderived super capacitors is still an urgent problem that needs to be solved.Herein,we rationally design and prepare three MOFs with the same crystal configuration and controllable functional groups.Through the combination of rigorous experiment and calculation,we have verified the effects of the specific surface area of the electrode material as well as the binding energy between the electrode material and the electrolyte ions on the performance of the super capacitor.This work not only extends the application of MOFs,but also provides a model-material platform for the study of charge–discharge behavior of MOF-based super capacitors,creating a way of thinking for the selection and design of MOF materials for energy storage applications.
基金This work was financially supported by the National K ey Basic Research Program of China(2014CB249200).
文摘With the increasing demand for clean renewable energy and electric cars,people have put forward higher requirement for the energy storage system.One of the most successful lithium-ion batteries with a cathode combination of lithium nickel manganese cobalt oxide(also called NCM lithium-ion battery),has been playing an increasingly important role.So far,numerous research has been done on the fabrication of cathode material with optimization of its composition,design,and assembly of the battery system in order to improve the energy storage performance.However,most of the previous studies were conducted based on relatively short cycling time of testing,with limited charge-discharge cycles of no more than 1000.Thus the conclusions were insufficient to be applied in the practical working condition.In this work,by using the developed NCM523 lithium-ion batteries,we have performed a series of ultra-long cycling tests on the individual cell and its module,with a comprehensive study on the relationship between the retained capacity after long cycling time and the depth of discharge(DOD),charge-discharge rate and operating temperature.Optimization of the charge-discharge strategies on a single cell and the whole module was also made to effectively improve the overall energy storage efficiency.This experimental study offers a guideline for the efficient use of similar types of lithium-ion batteries in the practical working condition.The developed batteries together with the optimized charge-discharge strategy proposed here are promising to meet the requirements for applications of stationary energy storage and electric cars.
基金This work was financially supported by the National Natural Science Foundation of China (No.10374053)
文摘Conducting polyaniline (PANI) powder was well mixed with graphite and acetylene black to obtain the optimum conductivity and porosity. The mixed powder was compressed into a pellet for cathode. Zinc powder was mixed with some metal powder, and compressed into a pellet used as the anode. The electrolyte comprised ZnCl2, NH4Cl, Triton-X100 and PVA at pH 3. The battery has an open-circuit voltage of 1.44 V. The battery underwent charge-discharge cycle with a constant current density of 3 mA·cm-2, within the voltage range of 0.40-1.68 V. It is found that the capacity of the battery is related to the charge-discharge cycles, the maximum capacity is 67.9 mAh·g-1, and Coulombic efficiency is between 95% and 100%. The battery stability was also investigated after 78 d of standing without use. It is found that the battery experiences a self-discharge of less than 0.29% per day.
基金supported by the National Natural Science Foundation of China(Nos.51972146,52072150).
文摘So far,a clear understanding about the relationship of variable energy band structure with the corresponding charge-discharge process of energy storage materials is still lacking.Here,using optical spectroscopy(red-green-blue(RGB)value,reflectivity,transmittance,UV-vis,XPS,UPS)to studyα-Co(OH)_(2) electrode working in KOH electrolyte as the research object,we provide direct experimental evidence that:(1)The intercalation of OH-ions will reduce the valence/conduction band(VB and CB)and band gap energy(Eg)values;(2)The deintercalation of OH-ions corresponds with the reversion of VB,CB and E_(g) to the initial values;(3)The color of Co(OH)_(2) electrode also exhibit regular variations in RGB value during the charge-discharge process.
基金supported by the Natural Science Foundation of Zhejiang Province(LY22E020006).
文摘Dielectric capacitors with high capacitive energy storage are urgently needed to meet the growing demand for high-performance energy storage devices.Herein,a novel lead-free Sr_(5)BiTi_(3)Nb_(7)O_(30)(SBTN)tungsten bronze relaxor ferroelectric ceramic is prepared and explored for potential energy storage applications.A high recoverable energy density Wrec(~3.72 J/cm^(3))and ultrahigh efficiencyη(~94.2%)at 380 kV/cm are achieved simultaneously.Both Wrec andηexhibit superior stabilities against temperature(30-140°C),cycles(100-105)and frequency(1-500 Hz).In addition,a high current density of 796 A/cm^(2) and a large power density of 71.7 MW/cm^(3) are achieved,together with good thermal endurance and fatigue resistance.These results demonstrate that the obtained SBTN ceramic can be deemed as the promising candidates for dielectric capacitor applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.11574057,and 12172093),the Guangdong Basic and Applied Basic Research Foundation(Grant No.2021A1515012607),and the Science and Technology Program of Guangdong Province of China(Grant No.2017A010104022).
文摘BaTiO_(3)(BT)has attracted extensive attention among advanced lead-free ferroelectric materials due to its unique dielectric and ferroelectric properties.However,the enormous remanent polarization and coercive field severely impede the improvement of its energy storage capabilities.Here,the BaTiO_(3)e-Bi(Zn_(0.5)Hf_(0.5))O_(3)(BT-BZH)ceramics with high breakdown field strength and remarkable relaxation characteristics can be obtained by introducing the composite component BZH in BT to regulate the phase structure and grain size of the ceramics.The findings demonstrate that the improvement of energy storage performance is related to the increase of relaxation behavior.A large energy storage density(Wrec~3.62 J/cm^(3))along with superior energy storage efficiency(h~88.5%)is achieved in 0.88BT-0.12BZH relaxor ceramics only at 240 kV/cm.In addition,the sample suggests superior thermal stability and frequency stability within 25e115℃and 1e500 Hz,respectively.Furthermore,the outstanding chargedischarge properties with an ultrafast discharge time(100 ns),large discharged energy density(1.2 J/cm^(3)),impressive current density(519.4 A/cm^(2))and power density(31.1 MW/cm^(3))under the electric field of 120 kV/cm are achieved in studied ceramics.The excellent energy storage performance of BT-BZH ceramics provides a promising platform for the application of lead-free energy-storage materials.
文摘In the last few decades,dielectric capacitors have gotten a lot of attention because they can store more power and charge and discharge very quickly.But it has a low energy-storage density(Wrec),efficiency(h),and temperature stability.By adding Pb(Mg1/3Nb2/3)O3(PMN)and(Bi0$1Sr0.85)TiO3(BST)to a nonstoichiometric(Bi0$51Na0.5)TiO3(BNT)matrix,the goal is to change the phase transition properties and make the material more relaxor ferroelectric(RFE)by lowering the remnant polarization Pr and keeping the maximum polarization Pmax.A viscous polymer process(VPP)is used to improve the electric breakdown strength,which is also a key part of being able to store energy.By working together,ceramics with the formula 0.79[0.85BNT-0.15PMN]-0.21BST(BP-0.21BST)are made.The phase structure has been changed from a rhombohedral phase to a rhombohedral-tetragonal coexisted phase.This is beneficial for RFE properties and gives a Wrec of 6.45 J/cm^(3) and a h of 90%at 400 kV/cm.Also,the energy-storage property is very temperature stable between 30 and 150C.These results show that process optimization and composition design can be used to improve the energy storage properties,and that the dielectric ceramic materials made can be used in high-powder pulse dielectric capacitors.
基金This work was supported by the defense preresearch project(104010108)the Fujian province natural science foundation(2014J01173)+1 种基金the key discipline of mechanical engineering in Fujian province(6112c1600)the Fujian province department of education(JA12100).
文摘To improve the low-temperature charge-discharge performance of lithium-ion battery,low-temperature experiments of the charge-discharge characteristics of 35 Ah high-power lithium-ion batteries have been conducted,and the wide-line metal film method for heating batteries is presented.At-40℃,heating and charge-discharge experiments have been performed on the battery pack.The results indicate the charge-discharge performance is substantially worse in cold climates,and can be significantly improved by heating the battery pack with a wide-line metal film.Pulse charge-discharge experiments show that at-40℃ambient temperature,the heated battery pack can charge or discharge at high current and offer almost80%power.
基金supported by Anhui Provincial Natural Science Foundation(1508085MB25)the National Natural Science Foundation of China(51274002 and 51404002)+1 种基金Anhui Provincial Science Fund for Excellent Young Scholars(gxyqZD2016066)the Program for Innovative Research Team in Anhui University of Technology(TD201202)
文摘Layered Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08-x)Al_xO_2(0 ≤ x ≤(0.08)) cathode materials were successfully synthesized by a sol-gel method. X-ray diffraction and the refinement data indicate that all materials have typical α-NaFeO_2 structure with R-3m space group, and the a-axis has almost no change, but there is a slight decrease in the c lattice parameter as well as the cell volume. Scanning electron microscopy and high resolution transmission electron microscopy prove that all the samples have uniform particle size of about 200–300 nm and smooth surface. The energy-dispersive X-ray spectroscopy mapping shows that aluminum has been homogeneously doped in the Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08)O_2 cathode material. The cyclic voltammetry and electrochemical impedance spectroscopy reveal that appropriate Al-doping contributes to the reversible lithium-ion insertion and extraction, and then reduces the electrochemical polarization and charge transfer resistance. Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08-x)Al_xO_2(x = 0.05)shows the lowest charge transfer resistance and the highest lithium-ion diffusion coefficient among all the samples. The Li-rich electrodes with low-level Al doping shows a much higher discharge capacity than the pristine one, especially the Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08-x)AlxO_2(x = 0.05) sample, which exhibits greater rate capacity and better fast charge-discharge performance than the other samples. Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08-x)Al_xO_2(x = 0.05) also exhibits higher discharge capacity than the pristine one at each cycle at 55°C. These results clearly indicate that the high rate capacity together with a good high rate cycling performance and high-temperature performance of the low-Co Li_(1.2)Mn_(0.56)Ni_(0.16)Co_(0.08-x)Al_xO_2(x=0.05) is a promising alternative to next-generation lithium-ion batteries.
基金This work was supported by NSFC(21621091)National Key Research and Development of China(2016YFB0100202)+4 种基金Natural Science Foundation of Fujian Province(2015J01063)the support of National Materials Genome Project(2016YFB0700600)National Key R&D Program of China(2016YFB0700600)the Guangdong Innovation Team Project(No.2013N080)Shenzhen Science and Technology Research(Nos.JCYJ20151015162256516,JCYJ20150729111733470 and JCYJ20160226105838578)。
文摘Layered Li-rich Mn-based oxides are promising cathode materials for Li-ion batteries due to their high capacity and high operation voltage.However,their commercial applications are hindered by irreversible capacity loss in the first charge-discharge process,voltage decay during cycling,inefficient cyclability and rate capability.Many attempts have been performed to solve such issues,including the mechanism study and strategies to improve the electrochemical performance.This article provides a brief review and future perspective on the main challenges of the high-capacity Li-rich Mn-based cathodes for Li-ion batteries.
基金supported by the Ministry of Science and Technology of China through the 973–Project under grant(2015CB654601)National Key R&D Program of China(2016YFA0201103)National Natural Science Foundation of China under Grant(No.51772211)and the Instrument Developing Project of Chinese Academy of Sciences(ZDKYYQ20180004).
文摘Increasing concern has been focused on the search for ecofriendly dielectric ceramics to meet the extensive demands of pulsed capacitors.Due to the advantages of high-energy storage density,efficiency,and excellent temperature stability,optimization of energy storage performance in dielectric ceramics has been a goal in the past decades.This review summarizes the recently reported progress in energy storage properties of typical perovskite-type lead-free ceramics.The advantages and shortcomings in the various kinds of ceramics are discussed.Finally,future prospects are presented to provide some guidelines for the exploration of new materials.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51902167,51902134)Natural Science Foundation of Ningbo City(Grant No.2021J064)+1 种基金Zhejiang Province Natural Science Foundation of China(Grant No.LY21E020002)Natural Science Foundation of Anhui Province(No.2008085ME133).
文摘Environmentally friendly lead-free ceramics capacitors,with outstanding power density,rapid charging/discharging rate,and superior stability,have been receiving increasing attention of late for their ability to meet the critical requirements of pulsed power devices in low-consumption systems.However,the relatively low energy storage capability must be urgently overcome.Herein,this work reports on leadfree SrTi_(0.875)Nb_(0.1)O_(3)(STN)replacement of(Bi_(0.47)La_(0.03)Na_(0.5))_(0.94)Ba_(0.06)TiO_(3)(BLNBT)ferroelectric ceramics with excellent energy storage performance.Improving relaxor behaviour and breakdown strength(Eb),decreasing grain size,and mitigating large polarization difference are conductive to the enhancement of comprehensive energy storage performances.The phase-field simulation methods are further analysized evolution process of electrical tree in the experimental breakdown.In particular,the 0.70BLNBT-0.30STN ceramic exhibit a large discharged energy density of 4.2 J/cm^(3) with an efficiency of 89.3%at room temperature under electric field of 380 kV/cm.Additionally,for practical applications,the BLNBT-based ceramics achieve a high power density(~62.3 MW/cm^(3))and fast discharged time(~148.8 ns)over broad temperature range(20-200℃).Therefore,this work can provide a simple and effective guideline paradigm for acquiring high-performance dielectric materials in low-consumption systems operating in a wide range of temperatures and long-term operations.
基金This work was supported by Natural Science Foundation of China(Nos.12064007 and 61761015)Natural Science Foundation of Guangxi(Nos.2018GXNSFFA050001,2017GXNSFDA198027 and 2017GXNSFFA198011)High Level Innovation Team and Outstanding Scholar Program of Guangxi Institutes.
文摘Lead-free ceramic capacitors have the application prospect in the dielectric pulse power system due to the advantages of large dielectric constant,lower dielectric loss and good temperature stability.Never-theless,most reported dielectric ceramics have limitation of realizing large energy storage density(W_(rec))and high energy storage efficiency(h)simultaneously due to the low breakdown electric field(E_(b)),low maximum polarization and large remanent polarization(P_(r)).These issues above can be settled by raising the bulk resistivity of dielectric ceramics and optimizing domain structure.Therefore,we designed a new system by doping(Bi_(0.5)Na_(0.5))_(0.7)Sr_(0.3)TiO_(3) into 0.9NaNbO_(3)-0.1Bi(Ni_(0.5)Zr_(0.5))O_(3) ceramics,which simulta-neously obtained a higher bulk resistivity by decreasing the grain size and achieved a smaller P_(r) by optimizing domain structure,thus the better E_(b) of 530 kV/cm and W_(rec) of 6.43 J/cm^(3) were achieved,h was improved from 34%to 82%.Besides,the 0.4BNST ceramics show excellent temperature,frequency and fatigue stability under the conditions of 20-180℃,1-100 Hz and 104 cycles,respectively.Mean-while,superior power density(P_(D)=107 MW/cm^(3)),large current density(C_(D)=1070 A/cm^(2))and discharge speed(1.025 m s)were achieved in 0.4BNST ceramic.Finally,the charge-discharge performance displayed good temperature stability in the temperature range of 30℃-180℃.The above results indicated that the ceramics have potential practical value in the field of energy storage capacitor.
基金This work was supported by the National Natural Science Foundation of China(Grant NO 51872177)The authors would also like to thank the Natural Science Basic Research Plan in the Shaanxi Province of China(Grant No.2022JQ-338,2021ZDLSF06-03,2021JM-201)+1 种基金Science and Technology Project of Xian,China(Grant No.2020KJRC0014)the Fundamental Research Funds for the Central Universities(Program No.GK202002014).
文摘Designing dielectric materials with the tremendous energy storage density is fundamentally important for developing pulse power capacitors.An effective approach was proposed to favorably modify the dielectric energy storage properties(ESP)of Bi_(0.5)Na_(0.5)TiO_(3) ceramics using CaTiO_(3) incorporation.The dielectric breakdown strength was effectively enhanced,and simultaneously the relaxor behavior was optimized to lower the remnant polarization,which is resulted from the decreased grains size with the introduction of Ca^(2+)ion.Remarkably,at a CaTiO_(3) doping level of 0.2,a 0.8Bi_(0.5)Na_(0.5)TiO_(3)-0.2CaTiO_(3)(0.8BNT-0.2CT)ceramic obtained both high energy storage density(Wtotal)of~1.38 J/cm^(3) together with excellent efficiency(h)of~91.3%.Furthermore,an ultrafast discharge response speed(t0:9)~94 ns was achieved in 0.8BNT-0.2CT ceramic,as well as tremendous current density(C_(D)~1520 A/cm2)and power density(P_(D)~115 MW/cm^(3)).This study not only revealed the superior ESP mechanism as regards Bi_(0.5)Na_(0.5)TiO_(3) based ceramics but also provided candidate materials in pulse power capacitor devices.
基金supported by the National Natural Science Foundation of China (50903078)Specialized Research Fund for the Doctoral Program of Higher Education (New Teachers) (20090132120017)Promotive Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province (BS2009CL036)
文摘Polyfluorene (PF) film has been successfully electropolymerized at lower potential (0.91 V vs.Ag/AgCl) in the mixed electrolyte of boron trifluoride diethyl etherate and trifluoroacetic acid.The PF film is characterized to have about 10 repeat units and no presence of ketonic defect site.UV-vis and photoluminescent spectral studies indicate that the PF film is blue light emitting.From cyclic voltammetry and galvanostatic charge-discharge tests in 1 M lithium perchlorate/acetonitrile electrolyte,the polyfluorene/activated carbon electrode shows a specific capacitance of 227.1 F g-1 (per active layer mass) and reversible redox reaction at the potential of 1.4 V in a three electrode configuration.An asymmetric electrochemical capacitor based on this composite electrode and activated carbon electrode exhibits a specific energy of 14.7 Wh kg-1 (per active layer mass).These results indicate that electrochemically prepared polyfluorene could be used as energy storage component for electrochemical application.
基金This study was carried out under the financial support of New Energy and Industrial Technology Development Organization,Research and Development of Innovative Robotic Components and its effective Manner of Utilization using Next Generation Functional Materials.We are quite grateful to Okura Industrial CO.,Ltd.(Kagawa,Japan)for providing us with the free sample of Silkron.
文摘Despite the promising characteristics of Dielectric Elastomel Actuator(DEA)as a practical soft actuator,the need of high voltage for its operation prevents the successful fabrication of a practical DEA,that is,the high voltage generation takes a bulky and costly power supply.Induction of complex shape change motion of DEA such as oscillatory shape change takes even a more bulky and costly multipurpose power supply.It is a serious practical issue to be overcome.In our latest study,however,we could build a simple DEA system which exhibited a relatively complex and autonomous oscillatory shape change merely under a constant voltage,though the voltage needed was high.This successful outcome must broaden the potential usefulness of DEA as a practical soft actuator.
文摘One-dimensional manganese oxide nanobelt bundles with birnessite-type structure have been synthesized by a hydrothermal process in a NaOH solution employing K-type layered manganese oxide as a precursor. The obtained manganese oxide nanobelt bundles exhibit excellent discharge properties and cycle stability. The initial capacity is 376 mAh-g-1 and the reversible capacity of 243 mAhog-1 is maintained after the 50th cycle at a current density of 20 mA·g-t. Meanwhile, the manganese oxide nanobelt bundles show an excellent cycle performance even if at relative high current density.
