The great thing about Li-ion batteries is that they can store a lot of energy, and that energy can be extracted very quickly. But that very benefit can also pose a problem. Today, we’re looking at battery safety.
Corrosion, Fire and Explosion
So, the ability of a Li-ion battery to accept, store and discharge a great amount of energy in a short time makes them fantastic for use in our EVs. But of course, having all this energy flying around can pose a risk. The main issue and potential for hazard have to do with the electrolyte. This is the stuff that the Lithium Ions move through when the battery is being charged and discharged. This ‘stuff’…I’m really putting my scientific hat on here folks!...so, this ‘stuff’ can be made of compounds that are corrosive and quite flammable. Now, that’s fine when it’s stored in the nice, safe casing of the battery…but not so much if it gets out or overheats!
So, if you’re going to have a problem with your battery, then it’s probably one or a combination of some main dangers. The first is corrosion, where the electrolytes leak out of the battery. The second is fire. The third is the battery potentially exploding.
So, we’ve just looked at some very basic things that can go wrong with a battery. But what about looking at how these things can happen. Well, there are some main culprits, so let’s look at those.
The first is physical damage to the battery. This could happen in any number of ways. If we were talking about mobile phones, it could be something like dropping your phone down the stairs. But if we’re talking about EVs, then we’re probably talking about a car crash. Suffice to say, that if the battery and its casing get damaged, this could lead to the electrolytes leaking out of the battery. And that is not good!
The next issue is a short circuit. This could also happen if the battery gets physically damaged. A short circuit causes the battery to heat up faster as it discharges. And the faster is discharges, the more it heats up. And so on, and so forth.
Responding to car accidents.
With ever-increasing numbers of EVs on roads, emergency services are having something extra to think about when responding to road incidents. Now, the idea of danger at a scene isn’t something new…60 liters of highly flammable petrol in a tank is a threat.
But a high voltage battery is something that Fire Services and Ambulances previously wouldn’t have thought of. Some newer EVs such as the Porsche Taycan are based on 800-volt architectures.
As we mentioned earlier, that voltage in a lithium-ion battery gives a great opportunity for high-speed charging and quick acceleration, but it also presents a hazard to a response crew that may have to cut a person out of a car following an accident. Thankfully, emergency services around the world are getting trained on how to handle such incidents safely.
How we charge our EVs is also a crucial part of Battery Safety. Thanks to regulations and improvements in safety standards, we can nearly always trust our chargers. But some dangers remain. The use of a ‘granny cable’, if used irresponsibly, can be a danger. Hiring an under-qualified person to install your charger may present dangers by using cheap or inappropriate materials. Cutting corners to save a few dollars here is probably not a good idea!
Structural battery packs
Let’s turn the idea of battery safety on its head for a moment and look at some connected aspects. We spoke of the integrity of the battery pack, and how damaging it could potentially cause a fire or explosion. So rigidity of the packs became a focus of research. It has continued to improve. And now manufacturers are learning to produce such robust battery packs that they are actually becoming part of the structural rigidity of the car. New and dedicated platforms are involving the battery packs in the structure of the vehicle, as opposed to simply building a chassis and then stuffing some batteries into various cavities.
Role of Battery Management Systems
Let’s end on the role of Battery Management Systems, because let’s face it, folks, the BMS does the heavy lifting! Thankfully we have next to nothing to think about in terms of battery safety. The BMS does the work for us.
Our EVs are fitted with software that allows them to control how our vehicles are charged, discharged, and to monitor the health and safety of the pack.
So, as we all know, there are millions and millions of li-ion batteries all around us….in our phones, our laptops, our children's toys, and our EVs. And in the vast, vast majority of cases, they work for their lifetimes without issue. There really is very little to worry about. Technology has improved, and it will continue to improve to make these products both more efficient and safer.