Mobile phone battery technology revealed why this explosion? Battery Samsung Note7, lithium-ion batteries-IT information

Don't know if you do not have share? Sitting recently in his Office, one heard around Samsung exclusive text message ringtone my heart will "click".

More than more than 30 "blow up" after the incident, Note 7 was "hatred", China and the United States there are security concerns, major airlines have battery block Note 7. Despite the stated its position on many occasions, Samsung SDI battery suppliers in battery explosion is blamed on the problem of different, contradictory, but mobile phone battery safety is no accident being pushed up into the air waves.

What batteries safely do? How to properly use the battery? Understanding of the issues, maybe you'll "blow up" a new understanding.

Why do cell phone battery explosion?

We now use the mobile phone battery is a lithium-ion battery, lithium-ion battery explosion caused by two common reasons: thermal and mechanical damage.

Overheating is the most common causes of lithium-ion battery explosion. This usually refers to the external factors causing thermal runaway, which is a part of the battery temperature rises, causing temperatures in other parts, so that the heating part more and more vicious, battery electrolyte begins to swell, steam appears, resulting in battery explosion because of the internal pressure is too high.

Mechanical damage is another reason, simply squeeze caused by a short circuit. Characteristics of lithium-ion batteries are lightweight and durable, from a bulky "big brother" to the light and stylish Smartphone today, battery improvement plays an important role. But because today we increasingly persistent pursuit for lightweight, lithium-ion batteries in design, its shell, and between positive and negative levels diaphragm more and more thin, this battery safety problems. Because once the diaphragm is damaged, it may cause a short circuit, resulting in batteries, internal heat production.

Note 7 explosion what kind of reason? Not long ago, Samsung said that "a rare mistake in the production process lead to the battery positive and negative touch, resulting in battery overheating", which seems to be describing an internal short circuit, but Samsung did not give more details.

Foreign Media based on the network described the explosion pictures and parties guessing, Note 7 explosion caused by mechanical damage caused by short circuit. Because in the multiple blasts, parties are not to charge mobile phones, no reference to the expansion of the mobile phone before the explosion occurred, and from the picture after the explosion, if overheating causes an explosion, mobile burn area should be greater.

Recently, SDI (Note 7 battery supplier) insiders also said that the explosion was due to a negative battery r-corner-short circuit problem.

Now what are the mark of a technique to prevent battery explosion?

It is important to note, either cause out of control, different battery of one form or another, and some will be on fire, but not necessarily explode.

In industry, for different safety problems, lithium-ion batteries will employ different security techniques, such as thermal fuses, Thermistors can be used to prevent a short circuit caused by overheating.

To prevent battery explosion, the traditional solution is to increase the safety valve. When the battery voltage is too high, the gas can escape out of the relief valve to prevent explosion.

Approach is similar to the thin battery case, this may sound a little weird, battery casing is thinner, not more prone to cracking? But, in fact, precisely because the slim battery casing to withstand less stress, so can the battery thermal runaway occurs, but the pressure has not reached dangerous levels when cracked, equivalent to form a safety valve.

There are also using fire-resistant electrolyte. Lithium-ion battery electrolytes are generally has a low boiling point, low flash point characteristics, once the battery is damaged, electrolyte is exposed to the air, probably poses the danger of explosion. Although developed both battery electrolyte ideal property without heat or open flames burning electrolyte is daydreaming, but increases the fire resistance of the electrolyte is still possible.

What kind of cell phone batteries more secure?

Not long ago, the famous iFixit teardown site leaks, Note 7 in the market outside China using lithium-ion batteries, instead of the more secure and safe lithium-ion polymer battery. So, here the polymer lithium-ion battery in the end is what? Do it more secure than other batteries?

First understand the classification of battery. Mobile phone battery has experienced the era of Nickel-chromium batteries and nickel-metal hydride batteries, and as said above, as has obvious advantages in performance compared with the previous two, lithium-ion batteries have become the mainstream of mobile phone batteries. But now, lithium-ion battery has also spawned many subclasses.

According to the electrolyte materials for lithium ion batteries, lithium ion batteries can be divided into liquid lithium-ion battery and lithium ion polymer batteries (lithium poly battery for short). The difference between the two is that using liquid electrolytes for lithium ion batteries, lithium ion polymer battery is "dry state" or "State" instead of solid polymer electrolyte. In addition, lithium-ion battery production costs are lower. Compared with ordinary liquid lithium-ion battery, lithium poly battery capacity not only higher, longer, more flexible, and because there are no leakage problems, security and more.

Pictures from the millet Forum is for reference only

Although, according to Samsung's previous position, Note 7 explosion design flaw is the direct cause, but as Note 7 battery capacity and fast charge technology upgrades, the risk of using lithium ion batteries has increased. By contrast, Apple, Huawei, HTC brand mobile phones are used together, such as lithium batteries, which, from the first generation of Apple iPhone lithium poly battery is used in the first place.

IFixit offers the first generation iPhone cell pictures

In this regard, has good friends in the Samsung website asked technology expert, Live Chat, their response is: Samsung and non-traditional lithium-ion batteries lithium-ion batteries, because the polymer lithium battery has high resistance problem, but compared with other more mature cells, lithium poly battery charge time is longer, lower maximum rate.

How can we avoid battery explosion?

But even in the relative safety of lithium poly battery is still possible because of high temperature, short-circuit, overcharge, suffered a heavy blow or battery damage, exploded. In theory, not a battery can be absolutely safe, security can only be relative to different standards.

Different battery safety standards

So, in normal use, we still want to avoid extremes, here are some lithium-ion battery safety guide:

Use original battery of mobile phone manufacturers, don't be cheap and use little-known manufacturers of batteries (although Note 7 this is very awkward, but the purchase of batteries will only increase the risk of the unknown);

Not at a temperature too high or too low (below freezing) environment charging, high temperature cause the battery to overheat, temperature is too low, the formation of metallic lithium anode surface in lithium Crystal lithium Crystal deposition will pierce the diaphragm causing short circuits within the battery (and now some have joined in a low temperature environment to prevent charging of the battery technology);

If you need to use some easy to make while charging your mobile phone fever features, or charging all night, it's best to remove the phone cover, to ensure that the batteries cool;

Keep the phone more than half of electricity is very helpful to extend battery life, vulnerable at low voltage as lithium ion battery;

Note that charging environment, try not to get in the vicinity of inflammable materials, car or recharge within the secure channel;

Finally, not in the mood for death! You may often see online child abuse video: with a knife, hit with a hammer, use a microwave oven baked ... ... Without wasting time to imitate, the outcome is likely to have only one-the explosion.

手机电池技术大揭密：为何会爆炸？ - 电池,三星Note7,锂电池 - IT资讯

不知道你们有没有同感？最近坐在办公室里，一听到身边响起三星专属短信铃声心里就会“咯噔”一下。

30多起“炸机”事件后，Note 7几乎成了“过街老鼠”，中国和美国日各大航空公司纷纷以电池存在安全隐患为由封杀Note 7。尽管在几次三番的表态中，三星与其电池供应商SDI在电池是否是爆炸元凶的问题上说法不一，前后矛盾，但手机电池安全还是毫无意外地被推上了风口浪尖。

目前电池安全做到什么地步了？如何正确使用电池？了解这些问题，或许你就会对“炸机”有全新的认识。

手机电池为什么会爆炸？

我们现在使用的手机电池大多是锂离子电池，引起锂离子电池爆炸的常见原因有两个：过热和机械损坏。

过热是锂离子电池发生爆炸最常见的原因。这通常是指外部因素引起热失控，也就是电池某一部分温度升高，进而导致其他部分温度升高，这样，电池发热部分越来越多，形成恶性循环，电池内电解质开始膨胀，蒸汽出现，最终导致电池因内压过大而爆炸。

机械损坏是另一个原因，简单来说就是挤压引起短路。锂离子电池有轻巧耐用的特点，从当年笨重的“大哥大”到今天轻薄时髦的智能机，电池的改良起到了重要作用。但也正是因为今天我们对于轻便越来越执着的追求，锂离子电池在设计上，其外壳和正负级之间的隔膜越来越薄，这就为电池安全埋下了隐患。因为一旦隔膜损坏，就可能引起短路，导致电芯内部产热。

那么Note 7爆炸属于哪种原因呢？不久前，三星曾表示“生产过程中一个罕见的错误导致电池正负极相触，造成电池过热”，这似乎是在描述内部短路，但目前三星没有对此给出更多细节。

有外媒依据网传的爆炸图片及当事人描述猜测，Note 7爆炸正是由机械损坏导致的短路引起。因为在多起爆炸事件中，当事人并没有在给手机充电，没有提到手机在爆炸前出现膨胀的情况，并且从爆炸后的图片来看，如果是过热导致的爆炸，手机烧毁面积应该更大。

最近有SDI（Note 7电池供应商）的内部人士也表示，爆炸是由于电池R角位出现了正负极短路的问题。

现在有哪些靠谱的技术可以防止电池爆炸？

需要说明的是，无论是哪种原因引起的失控，不同电池电芯的表现形式不同，有的会起火，但并不一定会爆炸。

在工业上，针对不同的安全问题，锂离子电池会采用不同的安全技术，例如热熔断器、热敏电阻可以用来防止短路引起的过热。

而在防止电池爆炸方面，最传统的解决方案是增加安全阀。当电池内压过大时，气体可以通过安全阀逃逸出去，从而阻止爆炸发生。

类似的办法是把电池外壳做薄，这可能听起来有点不可思议，电池外壳越薄，不就越容易开裂？但事实上，正是因为轻薄的电池外壳能够承受的压力更小，所以可以在电池发生热失控，但压力还没有达到特别危险的程度时及时裂开，相当于形成了一个安全阀。

另外还有使用抗燃型电解质。锂离子电池采用的电解质一般都具有低沸点、低燃点的特点，一旦电池受到损坏，电解质暴露在空气中，很可能就会带来爆炸的危险。虽然说，研制出既具电池电解质理想属性、又不会在遇热或明火时燃烧的电解质几乎是白日做梦，但是增加电解质的抗燃性还是有可能的。

什么样的手机电池比较安全？

前不久，著名拆机网站iFixit爆料，在中国以外市场发售的Note 7使用的都是锂离子电池，而不是更为稳妥安全的聚合物锂离子电池。那么，这里所说的聚合物锂离子电池到底是什么？它比其他电池更加安全吗？

首先了解一下电池的分类。手机电池曾经历过镍铬电池和镍氢电池时代，而正如上文所说，由于在性能上与前两者相比有明显优势，锂离子电池已成为主流的手机电池。但是现在，锂离子电池也衍生出了许多子类。

根据锂离子电池所用的电解材料，锂离子电池可以分为液态锂离子电池和聚合物锂离子电池（简称聚锂电池）。两者的区别就在于，液态锂离子电池使用的是液体电解质，聚合物锂离子电池则以“干态”或“胶态”的固体聚合物电解质来代替。此外，锂离子电池的生产成本要低一些。与普通液态锂离子电池相比，聚锂电池不仅容量更高、寿命更长、设计更加灵活，而且由于不存在漏液问题，安全性也更高。

图片来自小米论坛仅供参考

虽然根据三星此前的表态，设计缺陷才是Note 7爆炸的直接原因，但是随着Note 7电池容量增加以及快充技术的升级，使用液态锂离子电池的风险也随之增加。与之相比，目前苹果、华为、HTC等品牌手机均采用了聚锂电池，其中，苹果从第一代iPhone开始就采用了聚锂电池。

iFixit提供的第一代iPhone电池图片

对此，曾有好事的网友在三星官网的Live Chat上询问过技术专家，对方的回应是：三星采用传统锂离子电池而非聚锂电池，是因为聚锂电池有高电阻的问题，而且与其他更加成熟的电池技术相比，聚锂电池充电时间较长，最大放点速率较低。

如何能避免电池爆炸？

但即使是相对安全的聚锂电池，也依然有可能因为温度过高、短路、过度充电、遭遇重击或电池损坏等发生爆炸。理论上，没有一款电池可以做到绝对安全，安全只能是相对于不同的标准而言。

不同的电池安全标准

所以，在平时使用中，我们还是要避免极端情况，以下是部分锂离子电池安全使用指南：

使用手机生产商提供的原配电池，不要因贪图便宜而使用不知名的厂商生产的电池（虽然Note 7事件让这一条显得十分尴尬，但购买来路不明的电池只会增加风险）；

不要在温度过高或过低（低于零度）的环境中充电，温度过高容易引起电池过热，而温度过低时，金属锂会在负极表面析出形成锂结晶，锂结晶沉积会刺穿隔膜造成电池内短路（但现在有些电池已经加入了低温环境中阻止充电的技术）；

如果你需要在充电时使用某些容易使手机发热的功能，或彻夜充电，那么最好摘掉手机套，以保证电池正常散热；

保持手机有一半以上的电量对延长电池寿命很有帮助，因为锂离子电池在低电压下容易受损；

注意充电环境，尽量不要在易燃物附近、车内或安全通道内充电；

最后，不要花样作死！你可能经常在网上看到虐机视频：用刀扎、用锤子砸、用微波炉烤……不用浪费时间去模仿了，结局很可能只有一个——爆炸。