Zinc ion hybrid capacitors(ZIHCs),which integrate the features of the high power of supercapacitors and the high energy of zinc ion batteries,are promising competitors in future electrochemical energy storage applicat...Zinc ion hybrid capacitors(ZIHCs),which integrate the features of the high power of supercapacitors and the high energy of zinc ion batteries,are promising competitors in future electrochemical energy storage applications.Carbon-based materials are deemed the competitive candidates for cathodes of ZIHC due to their cost-effectiveness,high electronic conductivity,chemical inertness,controllable surface states,and tunable pore architectures.In recent years,great research efforts have been devoted to further improving the energy density and cycling stability of ZIHCs.Reasonable modification and optimization of carbon-based materials offer a remedy for these challenges.In this review,the structural design,and electrochemical properties of carbon-based cathode materials with different dimensions,as well as the selection of compatible,robust current collectors and separators for ZIHCs are discussed.The challenges and prospects of ZIHCs are showcased to guide the innovative development of carbon-based cathode materials and the development of novel ZIHCs.展开更多
The current collector is an indispensable component in potassium-ion hybrid capacitors,which not only provides mechanical support to load electrode materials,but also collects and outputs the current generated.Herein,...The current collector is an indispensable component in potassium-ion hybrid capacitors,which not only provides mechanical support to load electrode materials,but also collects and outputs the current generated.Herein,we investigate the effect of three different current collectors on the electrochemical properties of potassium ion capacitors using carbon black anode as a demonstration.Because of better adhesion and lower charge transfer resistance,the specific capacity of half-cells assembled using three-dimensional(3D)porous copper foil(PCu)and copper as current collector is better than that of Al foil,which stabilizes at 138.2 and 132.8 mAh·g^(-1)after 100 cycles at 0.05 A·g^(-1).The potassium-ion capacitor assembled using PCu exhibits an excellent energy/power density of 86.1 Wh·kg^(-1)and 4000 W·kg^(-1),respectively.This work will boost the rational design and provide an effective strategy to improve the performance of potassium-ion capacitors.展开更多
Objective For the inverters used in UPS, it is important to maintain the pure sinusoidal AC output voltage waveform over all loading conditions and transients. Methods A novel sinusoidal output voltage control strat...Objective For the inverters used in UPS, it is important to maintain the pure sinusoidal AC output voltage waveform over all loading conditions and transients. Methods A novel sinusoidal output voltage control strategy is pregented in this paper. The output voltage is controlled by introducing filtering eapacitor current feedback. Two simple PI regulators are used for the current and voltage control loops. Results With the new control strategy, the inverter achieves very low output voltage distortion, good output voltage regulation and strong perturbation rejection, fast dynamic response, and good performance under nonlinear loads. The THD under capacitance rectifying load is better than 0.2%, the output voltage regulation within 0 to full load is less than 0.1%. The resting time under load transient is within 200?μ s . Conclusion The merits of the new control strategy include rapid response and good steady state stiffness.展开更多
To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is prese...To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is presented in this paper. In our system, a switched capacitor filter (SCF) and an offset controller are also used to decrease vibrations and offset voltage at the output of the amplifier using SCNF. The theoretical output voltage of the very low level dc current amplifier using SCNF is obtained. The experimental results show that the unnecessary components of the amplifier’s output are much decreased, and that the response speed of the amplifier with both the SCNF and SCF is faster than that using high-ohmage resistor.展开更多
In this paper,an interleaved LCLC converter with enhancement-mode(E-mode)GaN devices is introduced to achieve the accurate current sharing performance for data center applications. Any tolerance in the resonant tank e...In this paper,an interleaved LCLC converter with enhancement-mode(E-mode)GaN devices is introduced to achieve the accurate current sharing performance for data center applications. Any tolerance in the resonant tank elements can lead to large load imbalance between any two different phases. Due to the steep gain curves of LCLC converters,conventional current sharing methods are not effective. In the proposed converter,the impedances of the resonant networks are matched by switching a capacitor,i.e.,switch controlled capacitor(SCC),in series with the resonant capacitor in one or some of the phases,which results in accurate load current sharing among the phases with an accuracy around 0.025%. The load share of a phase is sensed through the resonant current on it,and the control logic applied to such current sharing can be achieved. By this method,accurate current sharing is achieved for a wide input voltage range required for the hold-up time in data center applications. Interleaving is applied in the proposed multiphase LCLC converter,resulting in low current stress on the output capacitor and allowing ceramic capacitor implementation. Moreover,phase shedding accomplishes high light load efficiency. The performance of the proposed interleaved LCLC converter is verified by a two-phase 1 k W prototype with an input voltage ranging from 250 V to 400 V and a fixed 12 V output voltage.展开更多
Supercapacitors,comprising electrical double-layer capacitors(EDLCs)and pseudocapa-citors,are widely acknowledged as high-power energy storage devices.However,their local structures and fundamental mechanisms remain p...Supercapacitors,comprising electrical double-layer capacitors(EDLCs)and pseudocapa-citors,are widely acknowledged as high-power energy storage devices.However,their local structures and fundamental mechanisms remain poorly understood,and suitable experimental techniques for investigation are also lacking.Recently,nuclear magnetic resonance(NMR)has emerged as a powerful tool for addressing these fundamental issues with high local sensitivity and non-invasiveness.In this paper,we first review the limi-tations of existing characterization methods and highlight the advantages of NMR in investigating mechanisms of supercapacitors.Subsequently,we introduce the basic prin-ciple of ring current effect,NMR-active nuclei,and various NMR techniques employed in exploring energy storage mechanisms including cross polarization(CP)magic angle spinning(MAS)NMR,multiple-quantum(MQ)MAS,two-dimensional exchange spec-troscopy(2D-EXSY)NMR,magnetic resonance imaging(MRI)and pulsed-field gradient(PFG)NMR.Based on this,recent progress in investigating energy storage mechanisms in EDLCs and pseudocapacitors through various NMR techniques is discussed.Finally,an outlook on future directions for NMR research in supercapacitors is offered.展开更多
无线电能传输WPT(wireless power transfer)技术可在无人工辅助的条件下为无人机提供灵活便捷的电能补给,是未来无人机智能化发展的重要探索方向。为适应无人机WPT系统轻量化、恒流恒压充电、高能量传输效率等实际需求,提出了1种基于压...无线电能传输WPT(wireless power transfer)技术可在无人工辅助的条件下为无人机提供灵活便捷的电能补给,是未来无人机智能化发展的重要探索方向。为适应无人机WPT系统轻量化、恒流恒压充电、高能量传输效率等实际需求,提出了1种基于压控电容的无人机WPT系统高效率恒流/恒压输出调节方法。在系统发射线圈回路中采用压控电容作为补偿电容,通过动态调节该压控电容的等效阻抗,可在实现系统输出电流/电压有效控制的同时,保障宽负载范围条件下逆变器的软开关状态,且无需额外辅助电源及电感器件。详细分析了所提无人机WPT系统的工作原理及损耗模型,设计了1套完整的压控电容直流偏置电压调节模块、闭环控制策略及其参数设计方法。实验证明,在25.2 V-6 A的额定输出条件下,系统整体效率达88.8%。展开更多
基金the financial support from the National Natural Science Foundation of China(22108044)the 111 Project(B20088)+3 种基金the Fundamental Research Funds for the Central Universities(2572022DJ02)the Research and Development Program in Key Fields of Guangdong Province(2020B1111380002)the Basic Research and Applicable Basic Research in Guangzhou City(202201010290)the Guangdong Provincial Key Laboratory of Plant Resources Biorefinery(2021GDKLPRB07)。
文摘Zinc ion hybrid capacitors(ZIHCs),which integrate the features of the high power of supercapacitors and the high energy of zinc ion batteries,are promising competitors in future electrochemical energy storage applications.Carbon-based materials are deemed the competitive candidates for cathodes of ZIHC due to their cost-effectiveness,high electronic conductivity,chemical inertness,controllable surface states,and tunable pore architectures.In recent years,great research efforts have been devoted to further improving the energy density and cycling stability of ZIHCs.Reasonable modification and optimization of carbon-based materials offer a remedy for these challenges.In this review,the structural design,and electrochemical properties of carbon-based cathode materials with different dimensions,as well as the selection of compatible,robust current collectors and separators for ZIHCs are discussed.The challenges and prospects of ZIHCs are showcased to guide the innovative development of carbon-based cathode materials and the development of novel ZIHCs.
基金financially supported by the National Key Research and Development Program of China(No.2017YFE0198100)the National Natural Science Foundation of China(Nos.52072145 and 51802111)+4 种基金the Research Program on Science and Technology from the Education Department of Jilin Province(Nos.JJKH20220439KJ and JJKH20210450KJ)Jilin Talent Development Funding(No.2021Y027)the Funding of Jilin Province Development and Reform Commission(No.2020C026-2)Special Projects of the Central Government in Guidance of Local Science and Technology Development(No.202002017JC)Funding of JLNU Innovation Program for Graduate Education(No.202016)。
文摘The current collector is an indispensable component in potassium-ion hybrid capacitors,which not only provides mechanical support to load electrode materials,but also collects and outputs the current generated.Herein,we investigate the effect of three different current collectors on the electrochemical properties of potassium ion capacitors using carbon black anode as a demonstration.Because of better adhesion and lower charge transfer resistance,the specific capacity of half-cells assembled using three-dimensional(3D)porous copper foil(PCu)and copper as current collector is better than that of Al foil,which stabilizes at 138.2 and 132.8 mAh·g^(-1)after 100 cycles at 0.05 A·g^(-1).The potassium-ion capacitor assembled using PCu exhibits an excellent energy/power density of 86.1 Wh·kg^(-1)and 4000 W·kg^(-1),respectively.This work will boost the rational design and provide an effective strategy to improve the performance of potassium-ion capacitors.
文摘Objective For the inverters used in UPS, it is important to maintain the pure sinusoidal AC output voltage waveform over all loading conditions and transients. Methods A novel sinusoidal output voltage control strategy is pregented in this paper. The output voltage is controlled by introducing filtering eapacitor current feedback. Two simple PI regulators are used for the current and voltage control loops. Results With the new control strategy, the inverter achieves very low output voltage distortion, good output voltage regulation and strong perturbation rejection, fast dynamic response, and good performance under nonlinear loads. The THD under capacitance rectifying load is better than 0.2%, the output voltage regulation within 0 to full load is less than 0.1%. The resting time under load transient is within 200?μ s . Conclusion The merits of the new control strategy include rapid response and good steady state stiffness.
文摘To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is presented in this paper. In our system, a switched capacitor filter (SCF) and an offset controller are also used to decrease vibrations and offset voltage at the output of the amplifier using SCNF. The theoretical output voltage of the very low level dc current amplifier using SCNF is obtained. The experimental results show that the unnecessary components of the amplifier’s output are much decreased, and that the response speed of the amplifier with both the SCNF and SCF is faster than that using high-ohmage resistor.
文摘In this paper,an interleaved LCLC converter with enhancement-mode(E-mode)GaN devices is introduced to achieve the accurate current sharing performance for data center applications. Any tolerance in the resonant tank elements can lead to large load imbalance between any two different phases. Due to the steep gain curves of LCLC converters,conventional current sharing methods are not effective. In the proposed converter,the impedances of the resonant networks are matched by switching a capacitor,i.e.,switch controlled capacitor(SCC),in series with the resonant capacitor in one or some of the phases,which results in accurate load current sharing among the phases with an accuracy around 0.025%. The load share of a phase is sensed through the resonant current on it,and the control logic applied to such current sharing can be achieved. By this method,accurate current sharing is achieved for a wide input voltage range required for the hold-up time in data center applications. Interleaving is applied in the proposed multiphase LCLC converter,resulting in low current stress on the output capacitor and allowing ceramic capacitor implementation. Moreover,phase shedding accomplishes high light load efficiency. The performance of the proposed interleaved LCLC converter is verified by a two-phase 1 k W prototype with an input voltage ranging from 250 V to 400 V and a fixed 12 V output voltage.
基金supported by the National Natural Science Foundation of China(Grant No.22075064)National Key Laboratory Projects(No.SYSKT20230056).
文摘Supercapacitors,comprising electrical double-layer capacitors(EDLCs)and pseudocapa-citors,are widely acknowledged as high-power energy storage devices.However,their local structures and fundamental mechanisms remain poorly understood,and suitable experimental techniques for investigation are also lacking.Recently,nuclear magnetic resonance(NMR)has emerged as a powerful tool for addressing these fundamental issues with high local sensitivity and non-invasiveness.In this paper,we first review the limi-tations of existing characterization methods and highlight the advantages of NMR in investigating mechanisms of supercapacitors.Subsequently,we introduce the basic prin-ciple of ring current effect,NMR-active nuclei,and various NMR techniques employed in exploring energy storage mechanisms including cross polarization(CP)magic angle spinning(MAS)NMR,multiple-quantum(MQ)MAS,two-dimensional exchange spec-troscopy(2D-EXSY)NMR,magnetic resonance imaging(MRI)and pulsed-field gradient(PFG)NMR.Based on this,recent progress in investigating energy storage mechanisms in EDLCs and pseudocapacitors through various NMR techniques is discussed.Finally,an outlook on future directions for NMR research in supercapacitors is offered.
文摘无线电能传输WPT(wireless power transfer)技术可在无人工辅助的条件下为无人机提供灵活便捷的电能补给,是未来无人机智能化发展的重要探索方向。为适应无人机WPT系统轻量化、恒流恒压充电、高能量传输效率等实际需求,提出了1种基于压控电容的无人机WPT系统高效率恒流/恒压输出调节方法。在系统发射线圈回路中采用压控电容作为补偿电容,通过动态调节该压控电容的等效阻抗,可在实现系统输出电流/电压有效控制的同时,保障宽负载范围条件下逆变器的软开关状态,且无需额外辅助电源及电感器件。详细分析了所提无人机WPT系统的工作原理及损耗模型,设计了1套完整的压控电容直流偏置电压调节模块、闭环控制策略及其参数设计方法。实验证明,在25.2 V-6 A的额定输出条件下,系统整体效率达88.8%。
