Are lithium batteries safe? In what situations can they explode? | Estadão Mobility | Electric Planet

At the end of July, a video went viral on social media in which a lithium battery explodes in an elevator while a man is transporting it. The accident happened in China. This week, a new video is circulating around the internet. In it, two dogs left alone at home cause a fire after one of them bites a portable charger that used lithium batteries.

Punctures are a big risk. Therefore, hide batteries from animals or children. Video/Playback

Both incidents raise some questions. For example: Are lithium batteries really safe? Is there a risk of fire when using bicycles or cars with this equipment? How to stay safe?

Mobilidade Estadão interviewed two experts in the field to present measures that help avoid risks. Therefore, continue reading if you want to know more about the subject and find out how to protect yourself.

Find out more: Clarios shows battery that will run on sodium ions, water, wood and air

Why do lithium batteries explode?

“Batteries, in general, convert the energy of chemical compounds into electrical energy. The most classic and the one that conventional cars use is the battery that contains lead and sulfuric acid in its composition”, explains Célia Lino dos Santos, professor at IPT and Researcher at the Corrosion and Protection Laboratory (LCP-MA).

“In the lead acid battery, the electrodes are lead plates, in the lithium ion system there are different materials, electrodes based on graphite” comments the specialist.

The professor points out that in older lead batteries, the electrode (material used to conduct electrical ions) was sulfuric acid. Meanwhile, lithium batteries use organic solvent, which can ignite if it comes into contact with air.

At the same time, there is a small possibility that a lithium ion will leave the graphite structure that carries it. In this case, during the charging process, the ion would be reduced to metallic lithium. “The characteristic of these alkali metals is high reactivity, as they react very quickly with oxygen and humidity in the air. If it comes into contact with water, the reaction is intense and exothermic. In other words, it releases heat”, explains Célia.

Lead-acid batteries, in turn, are also not 100% safe. In these devices, there was a risk of users coming into contact with sulfuric acid, “a strong and very aggressive mineral acid, both for the skin and the environment”, says Célia. This model is also less advantageous than current lithium batteries.

Also read: The correct way to recycle and dispose of batteries

Benefits of lithium battery

Despite the above, Célia emphasizes that lithium batteries are safe and have several advantages. “The density of lithium is low. Therefore, with this material we were able to make much smaller batteries than lead-acid batteries.” It was advances in this area that allowed the emergence of electric vehicles and bicycles with compact batteries.

“Another brutal advantage that lithium offers is the energy itself; it has a much higher electrochemical potential than lead”, adds the expert.

“We only have electric cars that are economically viable because there are lithium batteries, which are lighter and have more power. If we only depended on lead batteries, we would be at the previous level (using only combustion cars)”

Célia Lino dos Santos, professor of Corrosion of Metallic Materials at USP

Are lithium batteries safe?

“Like all forms of energy storage, when well maintained and well used, the risk of fire is very low”, comments Ricardo Frazzato about lithium batteries. He is a businessman and founder of iPedal, a company that designs and manufactures batteries for electric bikes.

Frazzato argues that “to explode a battery, you need to have a combination of poor quality materials, wrong design and misuse”.

Professor Célia agrees and adds that the flammable components in a lithium battery do not make it any less safe. In fact, there are a series of safety standards to prevent these devices from causing fires.

“There is a device that batteries have, regardless of their size, called BMS, an acronym in English for Battery Management System”, explains Célia. BMS are also available in cars and bicycles.

The BMS monitors each of the battery cells, measuring energy level, temperature and other variables. If there is a risk, the BMS automatically disconnects the battery and prevents fires or explosions.

“In our project, when the battery has a problem, it goes into safe mode. The customer comes for technical assistance, receives a diagnosis and a repair or replacement, as appropriate. From an operational point of view, it is not at all complicated to do”, explains Frazzato about the BMS of the batteries that his company designs.

He further adds that “good quality lithium batteries have a fuse at the positive end. When the battery has a problem with excess current, temperature or internal pressure, it trips itself.” Finally, the businessman mentions that a good coating on the equipment and a good charger are also necessary.

What caused the explosions we see in videos and how to avoid them?

“In the case of dogs, unfortunately, they must have caused a puncture when biting the battery. When we produce this drilling, we really take risks”, explains Célia. “If you respect the packaging and don’t break this battery, the chance of an accident is greatly reduced,” she adds.

Bulging can also be a sign of imbalance within a battery. Therefore, if you find bubbles in the lithium battery of your bicycle or car, take it quickly to the responsible manufacturer or a collection point.

The gentleman who had an accident with a lithium battery in the elevator was probably using a device that had a BMS failure. The scenario, according to Célia, is rare.

In everyday life, to avoid explosions or damage, “very careful washing is necessary.” Electric bicycles cannot be washed with a pressure machine, they cannot sink in the river. A little rain is no problem, but respect your vehicle”, adds Frazzato.

“Frequent use of the battery also benefits its health. When storing, for example, for three months without using it, the ideal is to leave it with 50% of its charging capacity. When we store a discharged battery, it degrades very quickly”, concludes the businessman.

How can I be sure my battery is of good quality?

The main tool a user can turn to to make sure their lithium battery is safe is to purchase devices with BMS. It is easy to find batteries without this equipment on sales websites, however, in this case the risk is high.

Franzzato also emphasizes that it is necessary to “resist the temptation of easy fixes. If the BMS caused the battery to stop working there is a reason.” Therefore, homemade repairs or direct connections are not recommended and pose great danger.

When purchasing a device, “the customer should ask the seller or the company directly about the safety of the battery, serious companies have no difficulty demonstrating their safety”, adds the businessman.

Also read: Retro electric bicycle has two batteries and a range of more than 250 km

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Author: Fellipe.leite