For the battery only power system is hard to meet the energy and power requirements reasonably, a hybrid power system with uhracapacitor and battery is studied. A Topology structure is analyzed that the uhracapacitor ...For the battery only power system is hard to meet the energy and power requirements reasonably, a hybrid power system with uhracapacitor and battery is studied. A Topology structure is analyzed that the uhracapacitor system is connected with battery pack parallel after a bidirectional DC/DC converter. The ultracapacitor, battery and the hybrid power system are modeled. For the plug-in hybrid electric vehicle （PHEV） application, the control target and control strategy of the hybrid power system are put forward. From the simulation results based on the Chinese urban driving cycle, the hybrid power system could meet the peak power requirements reasonably while the battery pack＇ s current is controlled in a reasonable limit which will be helpful to optimize the battery pack＇ s working conditions to get long cycling life and high efficiency.展开更多
In this paper the cross correlation technique for measuring velocity of bulk material flow in pipe line was investigated and a new capacitance transducer with converter has been introduced. The system was controlled b...In this paper the cross correlation technique for measuring velocity of bulk material flow in pipe line was investigated and a new capacitance transducer with converter has been introduced. The system was controlled by single chip computer with a real-time cross correlation cumputing software. Computing time reaches 1 sec and velocity measuring error is less than 1%.展开更多
In this article, the replacement of the car battery by a hybrid supply is proposed. The specific power of the supercapacitor makes it very attractive for the startup of the car. This component has very high lifetime ...In this article, the replacement of the car battery by a hybrid supply is proposed. The specific power of the supercapacitor makes it very attractive for the startup of the car. This component has very high lifetime （1 million of cycles） which can improve the lifetime of the supply （for starter or starter-alternator）. After the identification of the internal combustion engine torque developed at the startup, the validation of the hybrid supply interest is proved by the simulation of the system using Matlab-Simulink software. Finally, a test bench is developed in the laboratory to validate the simulation results.展开更多
Research was undertaken to define the concept of a coach-based braking energy recoupment, storage and regeneration system to augment the acceleration of regional commuter trains hauled by diesel locomotives. Functiona...Research was undertaken to define the concept of a coach-based braking energy recoupment, storage and regeneration system to augment the acceleration of regional commuter trains hauled by diesel locomotives. Functional specifications were developed having the goal of increasing by 25% the acceleration rate of a train consisting of 10 bi-level coaches hauled by a 3,000 hp diesel locomotive, typical of the rolling stock now in commuter services in Canada and the USA. Examining three alternate hybrid system technologies for train retardation based, respectively, on hydrostatic, battery and ultracapacitor energy storage. The ultracapacitor hybrid system appeared the most promising due to the capability ofultracapacitors to repeatedly and rapidly accept large energy charges without degradation, temperature insensitive and flexible in the placement of modules in the limited space available. Analyses of train operation simulations showed that in addition to augmenting acceleration and reducing trip time, braking energy recoupment reduced fuel consumption and concomitant diesel emissions.展开更多
Activated carbon （AC） was fabricated by Coconut shell as carbon source, KOH as activator. Cyclic voltammetry and galvanostatic charge-discharge were used to characterize the electrochemical performance of the sample...Activated carbon （AC） was fabricated by Coconut shell as carbon source, KOH as activator. Cyclic voltammetry and galvanostatic charge-discharge were used to characterize the electrochemical performance of the samples. The results showed that： Supercapacitors based on the sample AC-3 have low Equivalent series resistanceb （ESR） and excellent power property.展开更多
In this work, a rational design and construction of porous spherical Ni O@NiMoO4 wrapped with PPy was reported for the application of high-performance supercapacitor(SC). The results show that the NiMoO4 modification ...In this work, a rational design and construction of porous spherical Ni O@NiMoO4 wrapped with PPy was reported for the application of high-performance supercapacitor(SC). The results show that the NiMoO4 modification changes the morphology of Ni O, and the hollow internal morphology combined with porous outer shell of Ni O@NiMoO4 and Ni O@NiMoO4@PPy hybrids shows an increased specific surface area(SSA), and then promotes the transfer of ions and electrons. The shell of NiMoO4 and PPy with high electronic conductivity decreases the charge-transfer reaction resistance of Ni O, and then improves the electrochemical kinetics of Ni O. At 20 Ag^-1, the initial capacitances of Ni O, NiMoO4, Ni O@NiMoO4 and Ni O@NiMoO4@PPy are 456.0, 803.2, 764.4 and 941.6 Fg^-1, respectively. After 10,000 cycles, the corresponding capacitances are 346.8, 510.8, 641.2 and 904.8 Fg^-1, respectively. Especially, the initial capacitance of Ni O@NiMoO4@PPy is 850.2 Fg^-1, and remains 655.2 Fg^-1 with a high retention of 77.1% at30 Ag^-1 even after 30,000 cycles. The calculation result based on density function theory shows that the much stronger Mo-O bonds are crucial for stabilizing the Ni O@NiMoO4 composite, resulting in a good cycling stability of these materials.展开更多
There is a growing demand for hybrid supercapacitor systems to overcome the energy density limitation of existing-generation electric double layer capacitors （EDLCs）, leading to next generation-Ⅱ supercapacitors wi...There is a growing demand for hybrid supercapacitor systems to overcome the energy density limitation of existing-generation electric double layer capacitors （EDLCs）, leading to next generation-Ⅱ supercapacitors with minimum sacrifice in power density and cycle life. Here, an advanced graphene-based hybrid system, consisting of a graphene-inserted Li4Ti5O12 （LTO） composite anode （G-LTO） and a three-dimensional porous graphene-sucrose cathode, has been fabricated for the purpose of combining both the benefits of Li-ion batteries （energy source） and supercapacitors （power source）. Graphene-based materials play a vital role in both electrodes in respect of the high performance of the hybrid supercapacitor. For example, compared with the theoretical capacity of 175 mA-h.g-1 for pure LTO, the G-LTO nanocomposite delivered excellent reversible capacities of 207, 190, and 176 mA·1h·g-1 at rates of 0.3, 0.5, and 1 C, respectively, in the potential range 1.0-2.5 V vs. Li/Li＋; these are among the highest values for LTO-based nano- composites at the same rates and potential range. Based on this, an optimized hybrid supercapacitor was fabricated following the standard industry procedure; this displayed an ultrahigh energy density of 95 Wh·kg-1 at a rate of 0.4 C （2.5 h） over a wide voltage range （0-3 V）, and still retained an energy density of 32 Wh·kg-1 at a high rate of up to 100 C, equivalent to a full discharge in 36 s, which is exceptionally fast for hybrid supercapacitors. The excellent performance of this Li-ion hybrid supercapacitor indicates that graphene-based materials may indeed play a significant role in next-generation supercapacitors with excellent electrochemical performance.展开更多
The charging kinetics of electric double layers （EDLs） is closely related to the performance of a wide variety of nanostructured devices including supercapacitors, electro-actuators, and electrolyte-gated transistor...The charging kinetics of electric double layers （EDLs） is closely related to the performance of a wide variety of nanostructured devices including supercapacitors, electro-actuators, and electrolyte-gated transistors. While room temperature ionic liquids （RTIL） are often used as the charge carrier in these new applications, the theoretical analyses are mostly based on conventional electrokinetic theories suitable for macroscopic electrochemical phenomena in aqueous solutions. In this work, we study the charging behavior of RTIL-EDLs using a coarse-grained molecular model and constant-potential molecular dynamics （MD） simulations. In stark contrast to the predictions of conventional theories, the MD results show oscillatory variations of ionic distributions and electrochemical properties in response to the separation between electrodes. The rate of EDL charging exhibits non-monotonic behavior revealing strong electrostatic correlations in RTIL under confinement.展开更多
文摘For the battery only power system is hard to meet the energy and power requirements reasonably, a hybrid power system with uhracapacitor and battery is studied. A Topology structure is analyzed that the uhracapacitor system is connected with battery pack parallel after a bidirectional DC/DC converter. The ultracapacitor, battery and the hybrid power system are modeled. For the plug-in hybrid electric vehicle （PHEV） application, the control target and control strategy of the hybrid power system are put forward. From the simulation results based on the Chinese urban driving cycle, the hybrid power system could meet the peak power requirements reasonably while the battery pack＇ s current is controlled in a reasonable limit which will be helpful to optimize the battery pack＇ s working conditions to get long cycling life and high efficiency.
基金This project is supported by the doctorate fund of State Education Commission
文摘In this paper the cross correlation technique for measuring velocity of bulk material flow in pipe line was investigated and a new capacitance transducer with converter has been introduced. The system was controlled by single chip computer with a real-time cross correlation cumputing software. Computing time reaches 1 sec and velocity measuring error is less than 1%.
文摘In this article, the replacement of the car battery by a hybrid supply is proposed. The specific power of the supercapacitor makes it very attractive for the startup of the car. This component has very high lifetime （1 million of cycles） which can improve the lifetime of the supply （for starter or starter-alternator）. After the identification of the internal combustion engine torque developed at the startup, the validation of the hybrid supply interest is proved by the simulation of the system using Matlab-Simulink software. Finally, a test bench is developed in the laboratory to validate the simulation results.
文摘Research was undertaken to define the concept of a coach-based braking energy recoupment, storage and regeneration system to augment the acceleration of regional commuter trains hauled by diesel locomotives. Functional specifications were developed having the goal of increasing by 25% the acceleration rate of a train consisting of 10 bi-level coaches hauled by a 3,000 hp diesel locomotive, typical of the rolling stock now in commuter services in Canada and the USA. Examining three alternate hybrid system technologies for train retardation based, respectively, on hydrostatic, battery and ultracapacitor energy storage. The ultracapacitor hybrid system appeared the most promising due to the capability ofultracapacitors to repeatedly and rapidly accept large energy charges without degradation, temperature insensitive and flexible in the placement of modules in the limited space available. Analyses of train operation simulations showed that in addition to augmenting acceleration and reducing trip time, braking energy recoupment reduced fuel consumption and concomitant diesel emissions.
文摘Activated carbon （AC） was fabricated by Coconut shell as carbon source, KOH as activator. Cyclic voltammetry and galvanostatic charge-discharge were used to characterize the electrochemical performance of the samples. The results showed that： Supercapacitors based on the sample AC-3 have low Equivalent series resistanceb （ESR） and excellent power property.
基金This work was supported by the National Natural Science Foundation of China(U1960107,21773060,51771046,and 51674068)the Fundamental Research Funds for the Central Universities(N182304014)Key Program for International S&T Cooperation Projects of China(2017YFE0124300).
文摘In this work, a rational design and construction of porous spherical Ni O@NiMoO4 wrapped with PPy was reported for the application of high-performance supercapacitor(SC). The results show that the NiMoO4 modification changes the morphology of Ni O, and the hollow internal morphology combined with porous outer shell of Ni O@NiMoO4 and Ni O@NiMoO4@PPy hybrids shows an increased specific surface area(SSA), and then promotes the transfer of ions and electrons. The shell of NiMoO4 and PPy with high electronic conductivity decreases the charge-transfer reaction resistance of Ni O, and then improves the electrochemical kinetics of Ni O. At 20 Ag^-1, the initial capacitances of Ni O, NiMoO4, Ni O@NiMoO4 and Ni O@NiMoO4@PPy are 456.0, 803.2, 764.4 and 941.6 Fg^-1, respectively. After 10,000 cycles, the corresponding capacitances are 346.8, 510.8, 641.2 and 904.8 Fg^-1, respectively. Especially, the initial capacitance of Ni O@NiMoO4@PPy is 850.2 Fg^-1, and remains 655.2 Fg^-1 with a high retention of 77.1% at30 Ag^-1 even after 30,000 cycles. The calculation result based on density function theory shows that the much stronger Mo-O bonds are crucial for stabilizing the Ni O@NiMoO4 composite, resulting in a good cycling stability of these materials.
基金The authors gratefully acknowledge financial support from Ministry of Science and Technology of the People＇s Republic of China （MOST） （Grants Nos. 2012CB933401 and 2011DFB50300）, and National Natural Science Foundation of China （NSFC） （Grants Nos. 50933003 and 51273093）.
文摘There is a growing demand for hybrid supercapacitor systems to overcome the energy density limitation of existing-generation electric double layer capacitors （EDLCs）, leading to next generation-Ⅱ supercapacitors with minimum sacrifice in power density and cycle life. Here, an advanced graphene-based hybrid system, consisting of a graphene-inserted Li4Ti5O12 （LTO） composite anode （G-LTO） and a three-dimensional porous graphene-sucrose cathode, has been fabricated for the purpose of combining both the benefits of Li-ion batteries （energy source） and supercapacitors （power source）. Graphene-based materials play a vital role in both electrodes in respect of the high performance of the hybrid supercapacitor. For example, compared with the theoretical capacity of 175 mA-h.g-1 for pure LTO, the G-LTO nanocomposite delivered excellent reversible capacities of 207, 190, and 176 mA·1h·g-1 at rates of 0.3, 0.5, and 1 C, respectively, in the potential range 1.0-2.5 V vs. Li/Li＋; these are among the highest values for LTO-based nano- composites at the same rates and potential range. Based on this, an optimized hybrid supercapacitor was fabricated following the standard industry procedure; this displayed an ultrahigh energy density of 95 Wh·kg-1 at a rate of 0.4 C （2.5 h） over a wide voltage range （0-3 V）, and still retained an energy density of 32 Wh·kg-1 at a high rate of up to 100 C, equivalent to a full discharge in 36 s, which is exceptionally fast for hybrid supercapacitors. The excellent performance of this Li-ion hybrid supercapacitor indicates that graphene-based materials may indeed play a significant role in next-generation supercapacitors with excellent electrochemical performance.
基金This work was supported as part of the Fluid Interface Reactions, Structures and Transport （FIRST） Center, an Energy Frontier Research Center funded by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences. K. X. is grateful to the Chinese Scholarship Council for a visiting fellowship. Additional support was provided by National Natural Science foundation of China （No. 21276138） and Tsinghua University Foundation （No. 2013108930）. The numerical calculations were performed at the National Energy Research Sdentific Computing Center （NERSC）.
文摘The charging kinetics of electric double layers （EDLs） is closely related to the performance of a wide variety of nanostructured devices including supercapacitors, electro-actuators, and electrolyte-gated transistors. While room temperature ionic liquids （RTIL） are often used as the charge carrier in these new applications, the theoretical analyses are mostly based on conventional electrokinetic theories suitable for macroscopic electrochemical phenomena in aqueous solutions. In this work, we study the charging behavior of RTIL-EDLs using a coarse-grained molecular model and constant-potential molecular dynamics （MD） simulations. In stark contrast to the predictions of conventional theories, the MD results show oscillatory variations of ionic distributions and electrochemical properties in response to the separation between electrodes. The rate of EDL charging exhibits non-monotonic behavior revealing strong electrostatic correlations in RTIL under confinement.
