电动汽车为改善空气质量、降低燃料成本提供了一条途径，并成为汽车制造商不断增长的新类别。但随着向电动交通的过渡，带来了新的挑战：配备锂离子电池的车辆着火时尤其危险。
好消息是电池电动汽车火灾并不经常发生。
澳大利亚墨尔本 EV FireSafe 项目总监 Emma Sutcliffe 表示，研究人员需要更多数据来最终确定火灾率，但初步研究表明，全电动汽车发生火灾的情况很少见。
另一家公司 AutoinsuranceEZ 的研究表明，电池电动汽车的点火几率仅为 0.03%，而内燃机汽车的点火几率为 1.5%。根据他们的研究，具有高压电池和内燃机的混合动力电动汽车发生车辆起火的可能性为 3.4%。
然而，当火灾确实发生时，配备锂离子电池的电动汽车会燃烧得更热、更快，并且需要更多的水才能最终灭火，Sutcliffe 说。并且电池可以在最初控制火灾数小时甚至数天后重新点燃，从而使打捞场、维修店和其他人处于危险之中。
宾夕法尼亚州下梅里恩消防局的首席消防官查斯·麦加维告诉 CNBC，他的部门在 2021 年处理的一场特斯拉 Model S 格子花呢大火燃烧得如此之热，以至于它融化了下面的道路。
萨特克利夫告诉 CNBC，“很多时候，消防员和消防机构只是希望能弄明白。”有这么多新车型上路，宾夕法尼亚州消防队长麦加维说：“我们仍在努力赶上所有这些东西。但它几乎每天都在变化！”
马里兰州能源研究所所长埃里克·瓦克斯曼 (Eric Wachsman) 表示，锂离子电池单元强大到足以移动乘用车的特性也可能使它们容易被点燃 - 特别是如果其中的电池单元损坏或有缺陷。
他说，锂离子电池的电极靠得很近，这增加了短路的机会，而且它们充满了易燃的液体电解质。
“这种易燃液体可能会进入所谓的热失控情况，它刚刚开始沸腾，并导致火灾，”他说。
电动汽车包括电池管理系统，以保持内部高压电池的正确工作温度，并且这些系统控制电池充电和放电的速度。对它们以及电池本身的改进有望使电动汽车更安全。
特斯拉最近宣布从锂离子电池转换为磷酸铁锂 (LFP) 电池。包括福特和大众在内的其他主要汽车制造商也在用 LFP 替代其部分电动汽车中使用的镍或钴配方。
“人们普遍认为这些更安全，”纽卡斯尔大学电化学教授保罗克里斯滕森说，他的研究重点是锂离子电池的火灾和安全。
他认为，最终，全电动汽车有机会比它们所取代的汽油或柴油车型更安全。
“我们花了很长时间来充分了解与汽油和柴油汽车相关的风险和危害。我们将不得不更快地学习如何应对电动汽车的挑战。但我们会的。”
Electric vehicle fires are rare, but hard to fight — here's why
Electric vehicles provide a path to better air quality, reduced fuel costs and comprise a growing new category for automakers. But with the transition to electric transportation comes a new challenge: Vehicles with lithium ion batteries can be especially dangerous when they catch fire.
The good news is battery electric vehicle fires don't happen often.
Project Director of EV FireSafe in Melbourne, Australia, Emma Sutcliffe, says researchers need more data to determine fire rates conclusively, but preliminary studies indicate fires in fully electric cars are rare.
Research by another firm, AutoinsuranceEZ, says battery electric vehicles have just a .03% chance of igniting, compared to internal combustion engine vehicle's 1.5% chance. Hybrid electrics, which have both a high voltage battery and an internal combustion engine, have a 3.4% likelihood of vehicle fires according to their study.
However, when fires do occur, electric vehicles with lithium ion batteries burn hotter, faster and require far more water to reach final extinguishment, Sutcliffe says. And the batteries can re-ignite hours or even days after the fire is initially controlled, leaving salvage yards, repair shops and others at risk.
Chas McGarvey, the Chief Fire Officer of Pennsylvania's Lower Merion Fire Department, told CNBC that one Tesla Model S Plaid fire his department handled in 2021 burned so hot that it melted the roadway beneath it.
Sutcliffe told CNBC, “A lot of the time fire fighters and fire agencies are just expected to kind of figure it out.” With so many new models hitting the road, McGarvey the fire chief in Pennsylvania said, “We're still trying to catch up with all this stuff. But it changes almost every day!”
The Director of Maryland's Energy Institute, Eric Wachsman, says that the qualities that make lithium ion battery cells powerful enough to move a passenger vehicle can also make them vulnerable to igniting-- especially if battery cells within them are damaged or defective.
Lithium ion battery cells have electrodes placed close together, which increases the chances of a short, he says, and they are filled with a flammable liquid electrolyte.
“This flammable liquid could get into what's called a thermal runaway situation where it just starts sort of boiling, and that results in a fire,” he said.
Electric vehicles include battery management systems to maintain the right operating temperature for high voltage batteries inside, and those systems control how fast batteries charge and discharge. Improvements to them as well as the battery cells themselves promise to make EVs safer.
Tesla recently announced it's switching from lithium ion battery cells to lithium iron phosphate (LFP) batteries. Other major automakers including Ford, and VW are also substituting LFPs for nickel or cobalt formulations used in some of their electric vehicles.
“These are generally believed to be a lot safer,” said Paul Christensen, a professor of electrochemistry at Newcastle University whose research focuses on lithium ion battery fires and safety.
In the end, he believes, fully electric vehicles have a chance to be safer than the gasoline- or diesel-burning models they replace.
“We've had a long time to fully understand the risks and hazards associated with petrol and diesel cars. We're going to have to learn faster how to deal with the challenges with electric vehicles. But we will.”
