 What's the deal with lithium-ion batteries and risk in planes? Lithium-ion batteries allow large amounts of energy to be squeezed into a very small volume and they allow that energy to be extracted very fast. This is fantastic news for airlines where lighter planes reduce environmental impact and increase profits. But as Boeing are discovering in their 787 Dreamliner, these benefits are not risk free. To understand how lithium-ion batteries potentially cause harm and how this might be avoided we really need to dig into the science behind the technology. We'll be doing this next week on Risk Bites but for now here are the risk highlights. The primary hazard in a lithium-ion battery is the electrolyte, the stuff that the lithium-ions move through when the battery is charged and discharged. This often contains an organic solvent that is corrosive and flammable, fine when it's sealed inside the battery, not so fine if it gets out or gets hot or both. Under the wrong conditions this stuff can cause problems through corrosion, fire and explosion. These are the associated risks but what are the wrong conditions that transform this hazard into a risk? There are four things you can do to a lithium-ion battery that transform its inherent hazard into a tangible risk. You can mechanically abuse it, you can short circuit it, you can overcharge it or you can heat it up. None of these are a good idea. Bashing the battery around for instance increases the chances of a breach in the casing leading to a release of corrosive electrolyte. It could also lead to an internal short circuit. Short circuits in lithium-ion batteries whether inside or outside are bad news. They cause the battery to heat up fast as it discharges and the hotter it gets the faster it heats up. When this happens the electrolyte vaporizes, pressure builds up and either flammable vapor is released or the battery explodes. And if your overheating battery is next to another one the heat produced could possibly start a knock-on reaction. Internal short circuits can be caused by rough handling but overcharging can also cause problems and turn a high hazard but low probability product into something you probably don't want to hang around with for any length of time. The good news is that a lot of technology goes into making lithium-ion batteries safe and it's getting better all the time. And even where the inherent hazard remains it's getting increasingly difficult to transform this into a significant risk. But as Boeing are finding out high hazard technologies need to be handled carefully if they're to be used successfully in low-risk products. Next week risk bites will be delving deeper into the science behind lithium-ion battery hazards and risks so stay tuned and stay safe.