双电层电容器的制备及性能

双电层电容器 (EDLC)是一种介于化学电源和静电电容器之间的新型储能元件 ,它有着比化学电源高出 10倍以上的功率密度 ,可与化学电源联用而组成未来电动汽车的混合动力系统。研制了圆柱形EDLC ,并测定了其在不同温度下的各种性能。实验研究结果表明 ,电容器的容量随着温度的升高线性增加 ,等效串联内阻随温度变化不大 ,漏电却随温度升高而增大。电容器的容量也与充放电电流密度有关 ,在一定电流密度范围内二者呈半对数关系。通过数千次的循环充放电可以看出 ,电容器的容量并没有较大的变化。     

Discharger using cascaded switched capacitor converters and selectable intermediate taps for electric double‐layer capacitors

Electric double‐layer capacitors (EDLCs) offer several advantages over traditional batteries, such as a long cycle life, high power capability, and good low‐temperature performance. However, their major drawbacks, such as low specific energy and large voltage variation due to charge/discharge cycling, necessitate the use of high‐efficiency power conversion electronics that can be used to efficiently discharge EDLCs and thus completely utilize the precious stored energy. In this study, we propose a novel discharger for EDLCs; this discharger uses cascaded switched capacitor converters (SCCs) and selectable intermediate taps. Although the voltage conversion ratio of SCCs is fixed, the load voltage can be maintained within a desired range by the selectable intermediate taps. The circuit configuration, operating principles, and procedure for designing SCCs and selectable intermediate taps are presented. Experimental tests were performed using an EDLC module and a 200‐W prototype of the discharger. The obtained results showed that the 60‐V EDLC could be discharged to 30 V with an average efficiency of 96% when the load voltage was maintained within the range of 30 to 40 V. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(3): 37–45, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22281     

超级电容器用高性能中孔活性炭的研究

以工业活性炭为原料,采用化学活化法以KOH为活化剂进行二次活化改性来提高活性炭的比表面积及吸附性能。研究了KOH用量、活化温度、停留时间等工艺参数对活性炭性能(包括比表面积、收率、亚甲基蓝吸附性能及双电层电容)的影响。实验结果表明,KOH二次活化显著提高了活性炭的BET比表面积,从原来的759 m2/g提高到2 200 m2/g,中孔率达到51.4%,亚甲基蓝的吸附量由245 mg/g提高到566 mg/g。随着热处理温度提高、KOH用量及停留时间的增加,活性炭的收率下降,比表面积增大,亚甲基蓝吸附能力及双电层电容提高。     

A method for designing the power and capacitance of fuel cells and electric double‐layer capacitors of hybrid railway vehicles

A hybrid railway traction system with fuel cells (FC) and electric double‐layer capacitors (EDLC) is discussed in this paper. This system can save FC costs and absorb regenerative energy. A method for designing FC and EDLC on the basis of the output power and capacitance, respectively, has not been reported, although their design is one of the most important technical issues encountered in the design of hybrid railway vehicles. Such a design method is presented along with a train load pro?le and an energy management strategy. The design results obtained using the proposed method are veri?ed by performing numerical simulations for a running train. These results reveal that the proposed method for designing the EDLC and FC on the basis of the capacitance and power, respectively, and using a method for controlling the EDLC voltage, is su?ciently e?ective in designing e?cient EDLC and FC of hybrid railway traction systems. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(3): 47–54, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22395     

离子液体/聚合物电解质在双电层电容器中的应用

以P(VDF-HFP)为基体,与离子液体1-乙基-3-甲基咪唑钅翁四氟硼酸盐(EMIBF4)和1-丁基-3-甲基咪唑钅翁六氟磷酸盐(BMIPF6)制备出离子液体/聚合物电解质凝胶膜,并组装了活性炭电极双电层电容器(EDLC)。基于EMIBF4/P(VDF-HFP)和BMIPF6/P(VDF-HFP)聚合物电解质(质量比2∶1)的双电层电容器,比电容分别为38.5 F/g和20.9 F/g。基于EMIBF4/P(VDF-HFP)的双电层电容器显示了优良的电化学性能。     

煤基活性炭用作双电层电容器电极材料

以云南小发路煤矿产无烟煤为原料,KOH为活化剂制取双电层电容器用高比表面积活性炭电极材料。系统考察了活化剂用量、活化时间和活化温度对活性炭电容特性的影响。研究结果表明,在mKOH/m无烟煤=4、升温速度为4℃/min、活化温度为750℃及保温时间为1h的工艺条件下,可制得双电极比电容达69.7F/g的无烟煤基高比表面积活性炭,由它组装的模拟双电层电容器具有良好的充放电性能和循环性能。     

Noncorrosive separator materials for electric double layer capacitor

The paper evaluates noncorrosive and inexpensive materials, namely polypropylene sheet, fiberglass, and glass wool, as potential separator materials for electric double‐layer capacitor (EDLC) application. Using these materials as separators and the same activated carbon electrodes, properties of two‐electrode capacitors filled with aqueous sulfuric acid (H₂SO₄) were investigated by cyclic voltammetry (CV) as well as galvanostatic and electrochemical impedance spectroscopy (EIS) measurements. Performance comparison of the tested capacitors with an identical capacitor with conventional cellulose separator was also carried out. As a benchmark, the noncorrosive‐separator‐based capacitors demonstrate comparable power and energy densities to those of a cellulose separator, with the highest specific capacitance of 131 F/g and lowest equivalent series resistance of 13 Ω for the glass wool separator. Application of such noncorrosive separators may realize the utilization of high‐concentration aqueous electrolytes, leading to higher rating EDLCs at lower cost compared to organic‐solution‐based capacitors. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A study of series‐parallel changeover circuit of a capacitor bank for an energy storage system utilizing electric double‐layer capacitors

Electric double‐layer capacitors showing a remarkably high energy density (compared with conventional electrolytic capacitors) are now under development. Capacitors of this type have significant advantages, namely, high durability against repeated charge and discharge and no need for maintenance. Therefore, we have studied feasible basic circuit configurations and control methods required to apply electric double‐layer capacitors as an energy storage element in output‐power leveling systems for solar cells or windmill power generators, and in uninterruptible power supply systems. This paper discussed operating methods for a capacitor bank to improve the efficiency. High efficiency has been demonstrated by the simulations and the experiments. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(3): 33–42, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10155     

碳纳米管/活性炭复合电极的电容特性

为改进活性炭电极组成的电双层电容器 (EDLC)的性能 ,采用碳纳米管 (CNT) /活性炭 (AC)复合材料制备可极化电极。考察了CNT对电容器性能的影响 ,用DC 5电池试验仪测试了其充放电性能、循环容量稳定性及自放电现象。结果表明 ,碳纳米管能有效地降低可极化电极的内阻 ,增强充放电循环稳定性 ,并降低EDLC的自放电速率。当复合电极中CNT含量为 5 % (质量百分数 )时 ,充电截止电压为 3V的条件下 ,CNT/AC复合电极的放电容量达 43F/g ,而AC电极仅 3 3F/g ,复合电极组成的EDLC的自放电速率下降约 5 0 %。     

Electric double‐layer capacitor module with series‐parallel reconfigurable cell voltage equalizers

When electric double‐layer capacitors (EDLCs) are connected in series, a cell voltage imbalance occurs due to nonuniform cell properties. Cell voltage imbalance should be minimized to prolong cycle lives and maximize the available energy of cells. In this study, we propose a series‐parallel reconfigurable cell voltage equalizer that is considered suitable for energy storage systems using EDLCs instead of traditional secondary batteries as the main energy storage sources. The proposed equalizer requires only EDLCs and switches as its main circuit elements, and it utilizes EDLCs not only for energy storage but also for equalization. An equivalent circuit model using equivalent resistors that can be regarded as an index of equalization speed is developed. Current distribution and cell voltage imbalancing during operation are quantitatively generalized. Experimental charge–discharge tests were performed on the EDLC modules to demonstrate the performance of the cell voltage equalizer. All the cells in the modules could be charged/discharged uniformly even when a degradation‐mimicking cell was intentionally included in the module. The resultant cell voltage imbalances and current distributions were in good agreement with those predicted by mathematical analyses. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(4): 38–50, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21287     

Active device‐less voltage equalization charger using capacitors,diodes, and an AC power source

Conventional cell/module voltage equalizers or equalization chargers based on traditional DC‐DC converters require numerous switches or transformers as the number of series connections increases; therefore, their cost and complexity tend to increase and their reliability decreases as the number of connections increases. This paper proposes a novel voltage equalization charger that consists only of passive components such as capacitors, diodes, and a transformer. The fundamental operating principle, major features, and derivation of equivalent DC circuits are presented. A symmetrical configuration is also proposed to mitigate the RMS current flowing through energy storage cells in the charging process. Simulations and experimental charging and cycle tests were performed on series‐connected electric double‐layer capacitor modules to demonstrate the equalization performance. The experimental and simulation results were in good agreement, and the voltage imbalances were gradually eliminated as time elapsed even during charge‐discharge cycling. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(3): 39‐48, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21288     

一种新型双电层超级电容器模型及其应用

提出了一种新型双电层超级电容器模型——改进2阶RC模型,该模型由瞬时、电压自调整、自放电3条支路组成,考虑了温度、端电压对超级电容器运行特性的影响,能够准确描述充放电过程中电压的非线性变化以及充放电之后的自调整特性。在详细介绍模型结构的基础上,给出一套通过恒流充电实验快速确定模型参数的辨识方法,具有较强的工程实用性。将此模型应用到超级电容器均压电路的设计中,采用单飞渡电容法均压策略,取得了良好的效果。     

Energy storage system utilizing large‐capacity electric double‐layer capacitors for peak‐cut of power demand

Recently, due to a rapid increase of demand for air conditioning in summer, peak power demand is becoming increasingly acute. Therefore, the load factor has a tendency to drop every year. The drop of the load factor is leading to a drop in the utilization factor of the power facilities and an increase in the cost of installation. In this paper, we propose an energy storage system for peak‐cut of power demand, in which we use large‐capacity electric double‐layer capacitors. This energy storage system has some distinctive characteristics, including long life span, maintenance‐free operation, preservation of environment, high efficiency at charge/discharge, and so on. This paper deals with the circuit arrangement of the proposed energy storage system, the charge equalization method of the capacitors, and the control method of the converter at charge/discharge. Finally, the operating characteristics of this system are evaluated by simulation analysis. © 2000 Scripta Technica, Electr Eng Jpn, 133(3): 83‐92, 2000     

微波辐射制备双电层电容器用竹炭

以毛竹废弃物为原料,KOH为活化剂,采用微波加热法制备出双电层电容器用活性炭.研究了不同微波功率对活性炭比电容量的影响,并考察了竹炭双电层电容器的充放电特性.结果表明:在KOH与毛竹质量比例为2∶1、微波功率为720 W和辐射时间为15 min时,制备出的活性炭比电容量达244.2 F/g,而且稳定性很好.     

高频变压器6集总电容等效电路模型转换

随着开关电源开关频率的不断升高,合理的高频变压器集总电容等效模型对功率变换器性能的分析具有极其重要的作用。首先介绍了已有的几类集总电容等效模型;其次,通过电路分析方法,研究了高频变压器几类集总电容模型的转换方法;最后,通过一款双绕组高频变压器的实际测试,论证了电容等效电路模型相互转换的可行性。     

超级电容器用炭材料的研究进展

综述了活性炭(AC)、活性炭纤维(ACF)、炭气凝胶、碳纳米管(CNTs)和模板炭等5种用于超级电容器的炭材料的性能和不足,展望了炭材料应用于超级电容器的发展方向.     

新型复合电化学电容器的研究

在单体碳/碳型双电层电容器的电极中分别添加一定量具有高容量性质的活性物质,构成正、负复合电极,活性物质经激活后即可在两极存储电能。该新型复合电容器与原碳/碳型双电层电容器相比,具有更高的稳定工作电压以及较高的单电极比容量,可有效改善双电层电容器的比能量及安全性能。根据所加活性物质比例及所选工作电压之不同,比能量可增加45%～70%。经不同电流密度恒流充放电试验,复合电容器的功率密度、充放电效率及循环寿命等性能良好,高容量活性物质的添加对双电层电容器较高的自放电现象具有一定的抑制作用。     

Double‐Switch Series‐Resonant Cell‐Voltage Equalizer Using a Voltage Multiplier for Series‐Connected Energy Storage Cells

Series connections of energy storage cells, such as lithium‐ion cells and electric double‐layer capacitors (EDLCs), require cell‐voltage equalizers to ensure years of operation. Conventional equalizers require multiple switches, magnetic components, and/or secondary windings of a multiwinding transformer in proportion to the number of series connections, which usually makes them complex, expensive, bulky, and less extendable with increasing series connections. A double‐switch series‐resonant equalizer using a voltage multiplier is proposed in this paper. The double‐switch operation without a multiwinding transformer achieves simplified circuitry and good modularity at reduced size and cost, compared to conventional equalizers. Operational analyses were separately performed for the following two functional parts of the proposed equalizer: a series‐resonant inverter and a voltage multiplier. The mathematical analyses derived a dc‐equivalent circuit of the proposed equalizer, with which simulation analyses of even an hour's duration can be completed in an instant. Simulation analyses were separately performed for both the original and equivalent circuits. The simulation results of the derived circuit correlated well with those of the original circuit, thus verifying the derived dc‐equivalent circuit. A 5‐W prototype of the proposed equalizer was built for eight cells connected in series and an experimental equalization was performed for series‐connected EDLCs from an initially voltage‐imbalanced condition. The voltage imbalance was gradually eliminated over time, and the standard deviation in the cell voltages decreased to approximately 5 mV at the end of the experiment, thus demonstrating the equalization performance of the proposed equalizer.     

Energy Saving Speed and Charge/Discharge Control of a Railway Vehicle with On-board Energy Storage by Means of an Optimization Model

The optimal operation of rail vehicle minimizing total energy consumption is discussed in this paper. In recent years, the energy storage devices have enough energy and power density to use in trains as on-board energy storage. The on-board storage can assist the acceleration/deceleration of the train and may decrease energy consumption. Many works on the application of the energy storage devices to trains were reported, however, they did not deal enough with the optimality of the control of the devices. The authors pointed out that the charging/discharging command and vehicle speed profile should be optimized together based on the optimality analysis. The authors have developed the mathematical model based on a general optimization technique, sequential quadratic programming. The proposed method can determine the optimal acceleration/deceleration and current commands at every sampling point under fixed conditions of transfer time and distance. Using the proposed method, simulations were implemented in some cases. The electric double layer capacitor (EDLC) is assumed as an energy storage device in our study, because of its high power density etc. The trend of optimal solutions such as values of control inputs and energy consumption is finally discussed. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Development of passive heat control system for direct methanol fuel cell using electric double layer capacitor

A direct methanol fuel cell (DMFC) is highly anticipated as a new, high‐density energy source for mobile usage; however, its poor power density presents a problem. As a result, the size of portable electronic equipment using DMFCs is far larger than that of equipment using another type of battery. In addition, steady power supply control is difficult, because the output power of the DMFC is affected by the environment. First, this paper presents a pulse charge control system that is a new control system applied to a mobile device, which uses the DMFC and an electric double layer capacitor (EDLC), then describes the new passive heat control and presents experimental results. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(1): 46–53, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21129