In our previous blog posts, we have mentioned safety as one of the key characteristics of batteries - if not the most important one. Additionally, we have shown different applications where batteries are handling an extremely hard workload while being expected to be efficient. These expectations and the complex chemistry which runs the batteries bring with them major potential risks. Accidents are rare, but those that do occur can be devastating, resulting in an explosion or fire. But what causes batteries to destroy like that?
What makes it burn and how bad is the fire?
In order to understand why batteries can catch on fire or explode, you first need to understand how they function. As we have touched upon in previous blog posts, one of the key features of a battery is how quickly it assumes energy when it is charging - the less time it takes the better. This causes a lot of heat generation. The losses mostly end up as heat, and the faster we charge the battery, the more energy we want to pump into it, and the faster it heats up. If something goes wrong - even in one cell of a battery - and it heats up too much, it becomes unstable and will heat up further much faster, eventually catching fire or exploding. As the neighboring cells get heated too, this instability can propagate very fast, causing a major fire with toxic fumes. Li-ion batteries heat up significantly when charged and discharged too quickly or when using the wrong charge voltage.
Because of the inherent instability of li-ion systems and easy propagation of the fire between the cells, battery-related fires are difficult to extinguish. Normal methods like water and powder are completely ineffective. You may need to dig the battery into sand or place it into a special fireproof package (today, airplanes do have those for consumer electronics). Burnt EVs often need to be immersed completely into a water tank to make sure that fire does not reignite. And if we step away from consumer electronics and look into the consequences of the fire at the power station or, say, at the electric bus which is operating using opportunity charging, the fire hazard is absolutely not acceptable.
Why does this matter?
The fire itself is only half of the problem. Complex organic electrolytes used in Li-ion batteries and contemporary supercapacitors release extremely toxic fumes when burning, including hydrogen cyanide and hydrogen fluoride. The release of these compounds, even in small doses in confined environments such as airplanes, underground or residential homes, may have worse consequences for humans than the fire itself
Once the used battery has to be transported for recycling, a new challenge presents itself: The transportation is not safe either. You may not know why the used battery was dumped and what might happen while it will be placed next to similar devices. Hence, even the recycling part of the battery’s journey needs to be heavily controlled in order to guarantee the full safety of the operations. This adds major costs to the second use of li-ion batteries and their recycling - to the extent that up to 95% of li-ion batteries actually end up in a landfill (where they are now an even bigger source of fire!).
What is the future?
Electrification is on the rise like never before and there is a major transition towards renewable energy. This means that clean energy, once it is captured, has to drive and run all types of vehicles, electronics and power grids. Hence, batteries will be coming in use 10 times faster, meaning that technology used for this has to be very stable, safe and cost-effective. While we see complex battery control and fire suppression systems being introduced along with electrolyte additives that reduce fire risks, the fundamental problem of fire hazardous and extremely toxic organic electrolytes remain. Their use is closely associated with the need for high energy density batteries, but for more and more applications, the issues of safety, sustainability and circular economy in the battery industry come into the foreground.
Realizing this, we at Geyser Batteries are working with cost-efficient electrolyte solvent like water. This is accessible, it has the least amount of environmental footprint, and it will not catch on fire - for obvious reasons. To learn about our methods, read more here: https://www.geyserbatteries.com/technology