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锂电池在运输中的危险性有哪些

时间:2012-7-27 14:41:17来源:本站原创浏览次数:

锂离子电池凭借其无与伦比的优势,应用的领域也越来越广,市场营销已走向国际化,同时锂电池又属于高危物品,因此的运输安全越来越受重视,现在是中国的夏季,高温和雨水都会容易对锂电池造成较大的影响,我们需要以更大的精力重视锂电池类货物安全运输。


锂电池的危险主要有以下几种:
漏液:leakage
外短路:external short circuit
内短路 internal short circuit
过充电 Overcharge
强制放电forced discharge
电气安全 Electrical Safety

漏液:leakage

电池设计和制造工艺的不良或受外部环境影响如UN38.3中T1-T4模拟的。电池可能漏液,通过测试确保电池在运输中不会漏液。包装要求即使有漏液也要保证运输安全。
The cell will leak if the design and producing process is not good and the cell will be affected by the condition as T1-T4 in UN38.3.We must be sure the cell will not leak during the transport through test .And the package instruct guarantees the transport will be safe even if the cell leaks

外短路:external short circuit

外短路如发生也是危险的,锂电池的温度会升的很高,甚至会发生着火、爆炸。UN38.3 中T5 模拟电池外短路,锂电池在经过T1-T4 运输中可能遇到的恶劣环境后进行外短路实验,可以说是最严厉的条件,锂电池在此条件下能满足安全要求,再加上在运输过程中包装等对电池的保护,可以排除此危险。
External short circuit will cause danger . The temperature of lithium batteries rises higher if happened ,and in certain condition battery will fire and explode.T5 in UN38.3 simulates external short circuit ,This test requires lithium battery is safe after it is subject to the special condition as T1-T4 in UN38.3. The package instruct also requires the protection for external short circuit .
着火后的锂电池图

内短路 internal short circuit

主要是电池隔膜不良或电池在生产过程中有导电小颗粒进入刺穿隔膜,还有锂离子电池在使用中由于过充等现象产生锂金属。内短路是锂电池着火、爆炸的主要原因,应该通过实验,改变设计减小锂电池的危险性。

The reasons to make the battery internal short circuit are (1)the separator is defective (2)little part of metal enters the cell during producing (3)Lithium metal comes into being because the battery is often overcharged . Internal short circuit is the main reason for fire and explosion by lithium battery .We should improvedesign to make the battery safe through test.

UN38.3 中T6 碰撞实验是模拟电池内短路的。当然现有的T6 碰撞不能很真实的模拟电池内短路情况,许多机构和专家正在研究更合适的实验方法,但在最近的UN38.3 草案中增加了挤压实验,而且大部分锂电池都要求用挤压实验,目前的挤压实验不能使很多电池形成内短路,对安全运输很不利,我们也提出自己意见,递交了正式文件
T6 in UN38.3 simulates the internal short circuit, As you know , It is incomplete same as the reality . Many experts in different institute are developing a good test method . In recent draft UN38.3 ,Crush test is used for most kinds of lithium cells. The crush test with 3000N can’t make most kinds of cells internal short circuit .It is not benefit for safe transport . We have submitted a formal document to express our opinion .

过充电 Overcharge

锂金属电池通常是不可充电的,所以不可能过充。
It is not fit for lithium metal battery. Most of them are primary.

锂离子电池在充电过程中,由于限压电路的失效或限定电压值偏离,会对电池过充,锂电池在过充条件下会有锂金属产生,有不稳定物质产生,电解液分解等使锂离子电池爆炸、着火,通常需要锂离子电池有过充保护。
Due to failure of the voltage limited circuit or deviation of the value of limited voltage , Lithium ion battery is often overcharged . Lithium metal comes into being ,Unstable substance is produced, the electrolyte is decomposed , Which will cause fire ,explosion and extreme temperature .Therefore lithium ion battery needs the protection for overcharge .
爆炸后的锂电池图
T7 实验就是验证锂离子电池的过充保护和过充安全性的。主要危险是使用过的电池
T7 in UN38.3 verifies the function of overcharge protection and the safety of the battery under overcharge . This danger mainly exists in the used batteries

强制放电forced discharge

锂金属电池在过放电时,会产生易爆炸的物质,在一定温度在会爆炸、着火在设计时应给于保护。
lithium metal cell will produce explosive substance when it is over-discharged . The explosive substance will explode under certain condition. Which should be protected .

锂离子电池在过放电时,会有铜等负极板材料析出。
The copper will be separated out on the positive polar if the lithium ion cell is over-discharged . It has an effect on performance .

T8实验就是检验电池在过放电时,也是安全的。
T8 in UN38.3 verifies the cell is safe under over-discharge condition.

电气安全 Electrical Safety

对大锂电池来说,大锂电池通常由许多电池芯串并联组成:
This is for larger lithium battery . Larger lithium battery is composed of a lot of small cells in parallel and in series.

由于串联,充电时只控制端电压,如何使每个电池芯的电压都相等是很重要的,不平衡将造成电池过充,产生危险。
Only terminal voltage of battery is controlled during charging .The cell blocks in serial must have a same voltage . If not ,some cell blocks must be overcharged , Overcharge will cause danger. So the cell consistency is very important.

由于并联,在每组并联电池中,一个电池由于内短路等原因电压下降,使这组电池中产生很大的电流,有可能导致电池爆炸、着火,我们应该也要有适当的实验,去避免这种危险发生。
Many cells are in parallel . If the voltage of one cell drops down due to internal short circuit or other reasons. The larger current will exist in this cell block . Which will make the cell fire or explode . We should pay more attention to this kind of danger .Developing a good test to avoid it .

另外,大锂电池电压较高,会造成高压击穿,耐压和绝缘阻抗等测试也是很有必要的。
Additional , larger lithium battery has high voltage ,High voltage will bring electrical danger . The test of High POT and insulated impedance is also needed .

在大电池中有电池管理系统,电池管理系统是由电池芯供电的,由于电池芯的能量很大,如果在印刷电流板上有短路,是否能保证电路板不着火等安全性也应该测试(在实验中我们经常发现规定螺丝脱落,很有可能会造成保护板短路)。
There is Battery management system (BMS) in the larger battery . BMS is powered by cell module ,If the short circuit happens on the circuit board , The larger current will flow the printed circuit board because the cell module has a large power . It is also possible for this current to make the printed circuit board fire . We should do some tests to avoid fire. (We often find the screw in the larger battery dropped out , It is possible for the screw to make the printed circuit board short circuit .)

 
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