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[信息] 锂聚合物与锂离子有什麽差别?

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发表于 2007-9-7 13:47:43 | 显示全部楼层 |阅读模式

锂聚合物与锂离子有什麽差别?
翻译: 张志炫 先生
感谢张先生的技术知识分享

原始文章
http://www.buchmann.ca/Article6-Page1.asp
最近锂聚合物已经成为尖端电池科技的代名词,但是锂聚合物与锂离子友什麽差别?
在本篇文章中我们将探讨这两种电池的差距,同时也将单位电力成本做一比较
锂聚合电池与其他电池最大的不同在传递电的介质不同,1970年当初的设计是做成像软片一样的材质,这种材质并不会传导电子但是会彼此交换离子(带电的原子)聚合物的电解质会填充在隔板的小缝隙间乾的聚合物很单纯是设计来使电池不易燃,安全,容易任意变形,这是液体或是胶质电解质所做不到的这种电池可以设计到只有1mm厚,工程师可以竭尽其想像将电池作成不同的形状如像草蓆般的捲起或是作成衣服的一部份,然而这些构想才刚开始,真正商业化还须一小段时间
不幸的是真正的锂聚合物导电性非常差,内电阻也非常大,无法提供瞬间大电流所须,而必须将聚合物加温到60度C或者更高才会有良好的导电性,因此这个特性非常不适合手提式的电子元件使用一些固态的锂聚合电池可以适用在炎热的气候环境下当成备用电力,而且必须加一个加热器让温度保持在适合导电的温度于是工程师们便开始研发适合在室温下可以正常操作的聚合物电池,预期到2005年后这种乾式的锂聚合电池技术可以让电池稳定的充放电达1000次并达到比现在锂离子电池更高电能密度的容量现在的锂聚合电池是如何在室温下操作的呢?现在大部分的锂聚合电池都是溷合着胶质电解质在乾的聚合物上,为了商业的目的,业者宣称是聚合物锂电池其实应该说是锂离子聚合物电池才洽当既然被加上胶值得电解质,那锂聚合物与锂离子有什麽差别其实两者的差距不大只是胶质的电解质取代了液态的锂离子电解质罢了其实锂离子聚合电池与锂离子电池的性能几乎一样,可能电量还会比较差,实在没有理由去取代锂离子电池,
原文如下:
The word ‘Lithium Polymer’ has become synonymous with advanced battery technology. But what is the relationship between ‘polymer’ and the classic Lithium Ion battery? In this article we examine the basic differences between the Li-ion and Li-ion polymer battery. We look at packaging techniques and evaluate the cost-to-energy ratio of these batteries.
The Li-polymer differs from other battery systems in the type of electrolyte used. The original design, which dates back to the 1970s, uses a polymer electrolyte. This electrolyte resembles a plastic-like film that does not conduct electricity but allows the exchange of ions (electrically charged atoms or groups of atoms). The polymer electrolyte replaces the traditional porous separator, which is soaked with electrolyte.
The dry polymer design offers simplifications with respect to fabrication, ruggedness, safety and thin-profile profile. There is no danger of flammability because no liquid or gelled electrolyte is used.
With a cell thickness measuring as little as one millimeter (0.039 inches), design engineers are left to their own imagination in terms of form, shape and size. Theoretically, it is possible to create designs which form part of a protective housing, are in the shape of a mat that can be rolled up, or are even embedded into a carrying case or a piece of clothing. Such innovative batteries are still a few years away, especially for the commercial market.
Unfortunately, the dry Li-polymer suffers from poor conductivity. The internal resistance is too high and cannot deliver the current bursts needed for modern communication devices and spinning up the hard drives of mobile computing equipment. Although heating the cell to 60°C (140°F) and higher increases the conductivity to acceptable levels. This requirement, however, is unsuitable for portable applications.
Some dry solid Li-polymers are currently used in hot climates as standby batteries for stationary applications. One manufacturer has added heating elements in the cells that keep the battery in the conductive temperature range at all times. Such a battery performs well for the application intended because high ambient temperatures do not degrade the service life of this battery in the same way as it does with the VRLA type. Although longer lasting, the cost of the Li-polymer battery is high.
Engineers are continuing to develop a dry solid Li-polymer battery that performs at room temperature. A dry solid Li-polymer version is anticipated by 2005. This battery should be very stable; would run 1000 full cycles and would have higher energy densities than today’s Li‑ion battery.
How then is the current Li-polymer battery made conductive at ambient temperatures? Most of the commercial Li-polymer batteries or mobile phones are a hybrid. Some gelled electrolyte has been added to the dry polymer. The correct term for this system is Lithium Ion Polymer. For marketing reasons, most battery manufacturers call it simply Li-polymer. Since the hybrid lithium polymer is the only functioning polymer battery for portable use today, we will focus on this chemistry variation but use the correct term of lithium ion polymer (Li-ion polymer).
With gelled electrolyte added, what then is the difference between Li‑ion and Li‑ion polymer? Although the characteristics and performance of the two systems are very similar, the Li‑ion polymer is unique in that the solid electrolyte replaces the porous separator. The gelled electrolyte is simply added to enhance ion conductivity.
Technical difficulties and delays in volume manufacturing have deferred the introduction of the Li‑ion polymer battery. In addition, the promised superiority of the Li‑ion polymer has not yet been realized. No improvements in capacity gains are achieved — in fact, the capacity is slightly less than that of the standard Li‑ion battery. For the present, there is no cost advantage in using the Li‑ion polymer battery. The major reason for switching to the Li-ion polymer is form factor. It allows wafer-thin geometries, a style that is demanded by the highly competitive mobile phone industry. Figure 1 summarizes the advantages and limitations of the Li-ion polymer battery.

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