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标题: 国外牛人总结的超级电容器 [打印本页]

作者: 大唐    时间: 2009-10-9 18:28     标题: 国外牛人总结的超级电容器

What's the role of the Supercapacitor? (BU8)

The supercapacitor resembles a regular capacitor with the exception that it offers very high capacitance in a small package. Energy storage is by means of static charge rather than of an electro-chemical process that is inherent to the battery. Applying a voltage differential on the positive and negative plates charges the supercapacitor. This concept is similar to an electrical charge that builds up when walking on a carpet. The supercapacitor concept has been around for a number of years. Newer designs allow higher capacities in a smaller size.

Whereas a regular capacitor consists of conductive foils and a dry separator, the supercapacitor crosses into battery technology by using special electrodes and some electrolyte. There are three types of electrode materials suitable for the supercapacitor. They are: high surface area activated carbons, metal oxide and conducting polymers. The high surface electrode material, also called Double Layer Capacitor (DLC), is least costly to manufacture and is the most common. It stores the energy in the double layer formed near the carbon electrode surface.

The electrolyte may be aqueous or organic. The aqueous variety offers low internal resistance but limits the voltage to one volt. In contrast, the organic electrolyte allows 2.5 volts of charge, but the internal resistance is higher.

To operate at higher voltages, supercapacitors are connected in series. On a string of more than three capacitors, voltage balancing is required to prevent any cell from reaching over-voltage.

The amount of energy a capacitor can hold is measured in microfarads or µF. (1µF = 0.000,001 farad). While small capacitors are rated in nano-farads (1000 times smaller than 1µF) and pico-farads (1 million times smaller than 1µF), supercapacitors come in farads.

The gravimetric energy density of the supercapacitor is 1 to 10Wh/kg. This energy density is high in comparison to a regular capacitor but reflects only one-tenth that of the nickel-metal-hydride battery. Whereas the electro-chemical battery delivers a fairly steady voltage in the usable energy spectrum, the voltage of the supercapacitor is linear and drops evenly from full voltage to zero volts. Because of this, the supercapacitor is unable to deliver the full charge.
If, for example, a 6V battery is allowed to discharge to 4.5V before the equipment cuts off, the supercapacitor reaches that threshold within the first quarter of the discharge cycle. The remaining energy slips into an unusable voltage range. A DC-to-DC converter could correct this problem but such a regulator would add costs and introduce a 10 to 15 percent efficiency loss.

Rather than operate as a main battery, supercapacitors are more commonly used as memory backup to bridge short power interruptions. Another application is improving the current handling of a battery. The supercapacitor is placed in parallel to the battery terminal and provides current boost on high load demands. The supercapacitor will also find a ready market for portable fuel cells to enhance peak-load performance. Because of its ability to rapidly charge, large supercapacitors are used for regenerative braking on vehicles. Up to 400 supercapacitors are connected in series to obtain the required energy storage capacity.

The charge time of a supercapacitor is about 10 seconds. The ability to absorb energy is, to a large extent, limited by the size of the charger. The charge characteristics are similar to those of an electrochemical battery. The initial charge is very rapid; the topping charge takes extra time. Provision must be made to limit the current when charging an empty supercapacitor.

In terms of charging method, the supercapacitor resembles the lead-acid battery. Full charge occurs when a set voltage limit is reached. Unlike the electrochemical battery, the supercapacitor does not require a full-charge detection circuit. Supercapacitors take as much energy as needed. When full, they stop accepting charge. There is no danger of overcharge or 'memory'.

The supercapacitor can be recharged and discharged virtually an unlimited number of times. Unlike the electrochemical battery, there is very little wear and tear induced by cycling and age does not affect the supercapacitor much. In normal use, a supercapacitor deteriorates to about 80 percent after 10 years.

The self-discharge of the supercapacitor is substantially higher than that of the electro-chemical battery. Supercapacitors with an organic electrolyte are affected the most. In 30 to 40 days, the capacity decreases from full charge to 50 percent. In comparison, a nickel-based battery discharges about 10 percent during that time.

Supercapacitors are relatively expensive in terms of cost per watt. Some design engineers argue that the money would be better spent in providing a larger battery by adding extra cells. But the supercapacitor and chemical battery are not necessarily in competition. Rather, they enhance one another.
Advantages
Limitations

作者: 杰克    时间: 2009-10-9 20:14

看不懂!!!!!!!!!
作者: ronwe    时间: 2009-10-10 10:31


作者: tiangyan    时间: 2009-10-14 09:47

好贴,不过因为是英文的估计会比较少人顶,谢谢LZ !
作者: bigdanchen    时间: 2009-10-18 14:40

感謝分享
作者: uranusman    时间: 2009-10-28 16:03

感谢分享啊
作者: mpowertech    时间: 2009-10-29 14:09

非常好的文章,学习
作者: liu100    时间: 2009-10-30 10:20

什么是超级电容器的角色? (BU8)

该超级像是一个例外,它提供一个小型套件非常高的电容经常电容器。储能是由静电的手段,而不是一个电化进程,固有的电池。应用的积极和消极板电压超级电容器收取不同的费用。这个概念类似于电荷积聚时的地毯上走过。该超级电容器的概念已经出现了数年。较新的设计允许在一个更小的尺寸更大的容量。

鉴于经常电容的导电箔和分离干组成的超级杂交利用一些特殊的电极和电解液到电池技术。有三种类型的电极材料的超级电容器合适。他们是:高比表面积活性炭,金属氧化物和导电聚合物。高表面电极材料,也被称为双电层电容器(金刚石),是生产成本最低,是最常见的。它存储在附近的碳形成的双层电极表面的能量。

电解液可能是水或有机。水溶液品种提供内阻低,但限制一伏的电压。相反,有机电解液允许收费2.5伏特,但内阻较高。

工作在更高的电压,超级电容器串联连接。在以上三个电容器串,需要平衡电压,以防止达成的任何细胞电压。

在能源电容可容纳量是衡量微或μF的。 (1μF的= 0.000,001法拉)。虽然小电容器的额定电压在纳米法拉(1000倍小于1μF的)和微微法拉(1万倍小于1uF的),在法拉电容器来。

该电容器重量能量密度为1至10Wh/kg。这种能量密度极高,比普通电容,但只反映十分之一的镍金属氢化物电池。鉴于电化学电池提供了一个在可用能量谱相当稳定电压,电容器的电压是线性的,从全电压下降到零伏均匀。正因为如此,该超级电容器是不能提供全费。
例如,如果一个6V的电池可以放电到4.5V的设备之前切断,内到达的超级电容器的放电周期的第一季度的门槛。其余的能量滑入一不可用电压范围。一个DC - DC转换器能够纠正这一问题,但这样的规会增加成本,并推出10至百分之十五的效率损失。

而不是作为一个主要的电池,超级电容器较常用的记忆备份桥梁短期电力供应中断。另外一个应用是提高电池的电流处理。该超级电容器是并联的电池终端,并提供了较高的负载电流的要求提高。该超级电容器也将找到一个便携式燃料电池现成的市场,以加强高峰负荷的性能。因为它能够快速充电,大型超级电容器用于再生制动车辆。最多400超级电容器串联连接,以获得所需的能量存储能力。

一个超级电容器充电时间约10秒钟。吸收的能力能量,在很大程度上限制了充电器的大小。的电荷特性类似的电化学电池的。最初的收费非常迅速,需要充电平顶额外的时间。必须要作出规定来限制电流充电时一空超级电容器。

在收费方法方面,类似于超级铅酸电池。充满电时发生的电压达到极限。不同的是电化学电池,超级电容器不需要完全充电检测电路。作为超级电容器的能量需要。当充分,他们停止接受收费。不存在危险或滥收费用的记忆'。

该超级电容器充电,并可以出院,几乎是无限次。电化学电池不同,很少有磨损的循环和年龄诱导不会影响超级电容器了。在正常使用,一个超级恶化到百分之八十左右,10年后。

的自我超级电容器大大高于电子的化学电池。与有机电解液超级电容器受到的影响最大。在30至40天,从全面负责的能力下降到百分之五十。相比之下,一镍基电池放电在百分之十左右的时间。

超级电容器是相对昂贵,每瓦成本方面。有些设计工程师认为,这笔钱将通过提供更好的细胞中添加额外的花费更大的电池。但是,超级电容器和化学电池并不一定竞争。相反,它们相互提高。优势

几乎无限的循环寿命-可循环数以百万计的时间。

低阻抗-增强的负载处理时,在与电池并联付诸表决。

快速充电,在几秒钟内电容器充电。

简单的收费方法-不完全充电检测需要,不滥收费用的危险。
限制

线性放电电压防止能源的充分利用频谱。
低能量密度-通常认为的五分之一到十分之一的电化学电池能量。
细胞具有低电压-串行连接需要获得更高的电压。需要平衡电压如果超过3个电容器串联。
高自放电-率大大高于一个电化学电池。
作者: 38738106    时间: 2009-11-25 15:55


作者: 冰红茶加可乐    时间: 2010-8-26 21:57

嘿嘿,俺是来拿分的。
作者: 冰红茶加可乐    时间: 2010-9-1 12:15

就是自放电的问题呀
作者: nm-ffs    时间: 2010-9-3 00:33

谢谢楼主分享!
作者: guojunpingguo    时间: 2010-9-11 21:28

非常关注,帮顶!
作者: bluemotion    时间: 2010-10-19 00:04

拿分很重要啊!!
作者: nm-ffs    时间: 2010-10-19 05:42

谢谢楼主分享!
作者: yu98719    时间: 2010-11-18 16:02

顶,好文章!{:5_202:}




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