In order to review storage performance of the electric double layer capacitor (EDLC) in microgrid applications, charging time and storage efficiency issues are mainly studied aiming at three different charging modes...In order to review storage performance of the electric double layer capacitor (EDLC) in microgrid applications, charging time and storage efficiency issues are mainly studied aiming at three different charging modes, including the constant voltage charging mode (CVCM), the constant current charging mode (CCCM) and the constant power charging mode (CPCM), based on the practical EDLC product. Numerical calculation methods are presented for different charging modes, and the charging efficiency is also reviewed with strict mathematical deductions, which is validated to be accurate enough and applicable through a simple case with the PV/EDLC system illustration. Finally, trade-off problems between charging time and energy loss are also studied. Research results show that the CPCM is more suitable for microgrid networks compared with the traditional constant-voltage and constant-current charging modes. The hybrid charging method is recommended to save energy and keep high efficiency relatively at the same time. However, how to manage the combination percentage of different charging modes in a reasonable way should be dealt with according to the practical requirements.展开更多
Electric double-layer capacitors(EDLCs) are emerging technologies to meet the ever-increasing demand for sustainable energy storage devices and systems in the 21 st Century owing to their advantages such as long lifet...Electric double-layer capacitors(EDLCs) are emerging technologies to meet the ever-increasing demand for sustainable energy storage devices and systems in the 21 st Century owing to their advantages such as long lifetime, fast charging speed and environmentally-friendly nature, which play a critical part in satisfying the demand of electronic devices and systems. Although it is generally accepted that EDLCs are suitable for working at low temperatures down to-40℃, there is a lack of comprehensive review to summarize the quantified performance of EDLCs when they are subjected to low-temperature environments. The rapid and growing demand for high-performance EDLCs for auxiliary power systems in the aeronautic and aerospace industries has triggered the urge to extend their operating temperature range,especially at temperatures below-40℃. This article presents an overview of EDLC’s performance and their challenges at extremely low temperatures including the capability of storing a considerable amount of electrical energy and maintaining long-term stability. The selection of electrolytes and electrode materials is crucial to the performance of EDLCs operating at a desired low-temperature range. Strategies to improve EDLC’s performance at extremely low temperatures are discussed, followed by the future perspectives to motivate more future studies to be conducted in this area.展开更多
Supercapacitors,or electric double-layer capacitors(EDLCs),are the new generation of energy storage devices to store electrical charges and provide high power densities and long cyclic life compared to other storage d...Supercapacitors,or electric double-layer capacitors(EDLCs),are the new generation of energy storage devices to store electrical charges and provide high power densities and long cyclic life compared to other storage devices.EDLC mainly consists of activated carbon electrodes and an electrolyte,and the performance of EDLC depends on the activated carbon electrodes.In this work,the structural changes of activated carbon electrodes are analyzed using commercial 2.7 V/9500F EDLCs in its manufacturing process.It is found that there is no significant change in morphology and crystal structure of the activated carbon,but its specific surface area(SSA)reduced greatly.The SSA of activated carbon was decreased by 23%after they were manufactured or converted into electrodes and finally retained only 40%of SSA after the capacitance test.Besides,the SSA of the positive electrodes was found to decrease critically than that of the negative electrodes.The SSA of the external positive electrodes is only 14.3%after fl oating test at 65℃.展开更多
The electrode materials as the key component of supercapacitors have attracted considerable research interests, especially for nickel/cobalt based materials by virtue of their superior electrochemical performance with...The electrode materials as the key component of supercapacitors have attracted considerable research interests, especially for nickel/cobalt based materials by virtue of their superior electrochemical performance with multiple oxidation states for richer redox reactions, abundant natural resources, lower prices and toxicity. There are many advanced electrodes based on the nickel/cobalt materials exploited for the application of supercapacitors, however, some controversial statements have induced some confusion. Herein, we refine the mechanism of energy storage for the nickel/cobalt based materials for supercapacitors and reclassify them into battery-type materials with the corresponding devices named as hybrid supercapacitors.展开更多
The effects of particle size of activated carbon (AC) on its wettability, electrode coating technology and electric chemical performance were studied to assemble nonaqueous electric double layer capacitors (EDLCs)...The effects of particle size of activated carbon (AC) on its wettability, electrode coating technology and electric chemical performance were studied to assemble nonaqueous electric double layer capacitors (EDLCs) for high power requirements. The results show that the specific surface area and total pore volume of AC decrease from 2 137 m^2/g to 1 683 m^2/g, and 0.95 cm^3/g to 0.78 cm^3/g, respectively, if it is ball-milled for 8 h. The pore size distributions are similar in the range of 0.7 nm to 3.5 nm for different ball-milling time. There exists oxidation on the surface of AC during the ball-milling process and the ratios of O-C=O oxygen compositions increase whereas those of C-O, C=O decrease. The peeling strength of AC coated on current collector is almost inverse proportion with the particle size of AC as well as the resistance of EDLCs, and its capacitance decreases about 6%.展开更多
The conventional liquid electrolytes(LEs) have a high level of ionic conductivity;however, they often suffer from the poor processability and safety risks of potential leakage. Although solid-state electrolytes(SSEs) ...The conventional liquid electrolytes(LEs) have a high level of ionic conductivity;however, they often suffer from the poor processability and safety risks of potential leakage. Although solid-state electrolytes(SSEs) can solve these inherent problems of LEs, the ionic conductivity of most SSEs is several magnitudes lower than these of LEs. Herein, we report a novel strategy by building liquid ion-transport channels in a solid framework and prepared an electrolyte-locked separator(ELS) using a collagen fiber membrane(CFm). The liquid electrolyte was primarily infiltrated in the smaller voids of CFm, and its ionic conductivity could attain to 9.0×10-3 S cm-1 when the electrolyte absorption(EA) reached up to 112.0%. After centrifuging treatment, the electrolyte retentions(ER) and ionic conductivities of ELS were 108.93% and 8.37×10-3 S cm-1, respectively, which were much higher than those of commercial cellulose separator(CS), exerting excellent liquid-locking performances. In particular, the electrical double-layer capacitors(EDLC) assembled by ELS or CS were characterized and exhibited similar electrochemical performance,demonstrating the satisfactory ability and applicability of ELS for commercial use. In addition, the ELSbased EDLC exhibited favorable flexibility with relative lower loss of capacitance under different angles of bending.展开更多
基金The National Natural Science Foundation of China (No.50907010)Ph.D.Programs Foundation of Ministry of Education of China(No.20070286047)Scientific Innovation Foundation for Youngsters of CSEE
摘要In order to review storage performance of the electric double layer capacitor (EDLC) in microgrid applications, charging time and storage efficiency issues are mainly studied aiming at three different charging modes, including the constant voltage charging mode (CVCM), the constant current charging mode (CCCM) and the constant power charging mode (CPCM), based on the practical EDLC product. Numerical calculation methods are presented for different charging modes, and the charging efficiency is also reviewed with strict mathematical deductions, which is validated to be accurate enough and applicable through a simple case with the PV/EDLC system illustration. Finally, trade-off problems between charging time and energy loss are also studied. Research results show that the CPCM is more suitable for microgrid networks compared with the traditional constant-voltage and constant-current charging modes. The hybrid charging method is recommended to save energy and keep high efficiency relatively at the same time. However, how to manage the combination percentage of different charging modes in a reasonable way should be dealt with according to the practical requirements.
基金the Australian Research Council for its support through the Discovery Project scheme (DP190103186)the Industrial Transformation Training Centre Scheme(IC180100005)。
摘要Electric double-layer capacitors(EDLCs) are emerging technologies to meet the ever-increasing demand for sustainable energy storage devices and systems in the 21 st Century owing to their advantages such as long lifetime, fast charging speed and environmentally-friendly nature, which play a critical part in satisfying the demand of electronic devices and systems. Although it is generally accepted that EDLCs are suitable for working at low temperatures down to-40℃, there is a lack of comprehensive review to summarize the quantified performance of EDLCs when they are subjected to low-temperature environments. The rapid and growing demand for high-performance EDLCs for auxiliary power systems in the aeronautic and aerospace industries has triggered the urge to extend their operating temperature range,especially at temperatures below-40℃. This article presents an overview of EDLC’s performance and their challenges at extremely low temperatures including the capability of storing a considerable amount of electrical energy and maintaining long-term stability. The selection of electrolytes and electrode materials is crucial to the performance of EDLCs operating at a desired low-temperature range. Strategies to improve EDLC’s performance at extremely low temperatures are discussed, followed by the future perspectives to motivate more future studies to be conducted in this area.
基金the Major Special Projects of the Plan“Science and Technology Innovation 2025”in Ningbo(No.2019B10045)the Key Project of CRRC(No.2019CKB198).
摘要Supercapacitors,or electric double-layer capacitors(EDLCs),are the new generation of energy storage devices to store electrical charges and provide high power densities and long cyclic life compared to other storage devices.EDLC mainly consists of activated carbon electrodes and an electrolyte,and the performance of EDLC depends on the activated carbon electrodes.In this work,the structural changes of activated carbon electrodes are analyzed using commercial 2.7 V/9500F EDLCs in its manufacturing process.It is found that there is no significant change in morphology and crystal structure of the activated carbon,but its specific surface area(SSA)reduced greatly.The SSA of activated carbon was decreased by 23%after they were manufactured or converted into electrodes and finally retained only 40%of SSA after the capacitance test.Besides,the SSA of the positive electrodes was found to decrease critically than that of the negative electrodes.The SSA of the external positive electrodes is only 14.3%after fl oating test at 65℃.
基金supported by the National Natural Science Foundation of China(No.51672109)Natural Science Foundation of Shandong Province for Excellent Young Scholars(No.ZR2016JL015)
摘要The electrode materials as the key component of supercapacitors have attracted considerable research interests, especially for nickel/cobalt based materials by virtue of their superior electrochemical performance with multiple oxidation states for richer redox reactions, abundant natural resources, lower prices and toxicity. There are many advanced electrodes based on the nickel/cobalt materials exploited for the application of supercapacitors, however, some controversial statements have induced some confusion. Herein, we refine the mechanism of energy storage for the nickel/cobalt based materials for supercapacitors and reclassify them into battery-type materials with the corresponding devices named as hybrid supercapacitors.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.50672025, 50730003), and the Science Foundation of Shanghai Municipal Commission of Science and Technology (Grant Nos.06JC14018, 06DZ22003)
摘要The effects of particle size of activated carbon (AC) on its wettability, electrode coating technology and electric chemical performance were studied to assemble nonaqueous electric double layer capacitors (EDLCs) for high power requirements. The results show that the specific surface area and total pore volume of AC decrease from 2 137 m^2/g to 1 683 m^2/g, and 0.95 cm^3/g to 0.78 cm^3/g, respectively, if it is ball-milled for 8 h. The pore size distributions are similar in the range of 0.7 nm to 3.5 nm for different ball-milling time. There exists oxidation on the surface of AC during the ball-milling process and the ratios of O-C=O oxygen compositions increase whereas those of C-O, C=O decrease. The peeling strength of AC coated on current collector is almost inverse proportion with the particle size of AC as well as the resistance of EDLCs, and its capacitance decreases about 6%.
基金supported by the National Natural Science Foundation of China (21878191)。
摘要The conventional liquid electrolytes(LEs) have a high level of ionic conductivity;however, they often suffer from the poor processability and safety risks of potential leakage. Although solid-state electrolytes(SSEs) can solve these inherent problems of LEs, the ionic conductivity of most SSEs is several magnitudes lower than these of LEs. Herein, we report a novel strategy by building liquid ion-transport channels in a solid framework and prepared an electrolyte-locked separator(ELS) using a collagen fiber membrane(CFm). The liquid electrolyte was primarily infiltrated in the smaller voids of CFm, and its ionic conductivity could attain to 9.0×10-3 S cm-1 when the electrolyte absorption(EA) reached up to 112.0%. After centrifuging treatment, the electrolyte retentions(ER) and ionic conductivities of ELS were 108.93% and 8.37×10-3 S cm-1, respectively, which were much higher than those of commercial cellulose separator(CS), exerting excellent liquid-locking performances. In particular, the electrical double-layer capacitors(EDLC) assembled by ELS or CS were characterized and exhibited similar electrochemical performance,demonstrating the satisfactory ability and applicability of ELS for commercial use. In addition, the ELSbased EDLC exhibited favorable flexibility with relative lower loss of capacitance under different angles of bending.