There is a tension between making batteries that are safe and batteries powerful enough to support consumer's ever increasing expectations for more powerful mac

There is a tension between making batteries that are safe and batteries powerful enough to support consumer's ever increasing expectations for more powerful machines. Battery makers have to weight making a battery more devoted to batter materials (more electrical storage) versus more casing (to control the contents). It just boils down to chemistry: we're trying to jam a huge amount of energy into a small place, yet release it in a controlled manor. Li-ion batteries have a membrane that separates the two side of the battery. If it has a defect any any manor, it turns into an uncontrolled release. A 30 watt battery can power a 30 watt light bulb for a full hour. It doesn't seem like a lot of light and heat, but that is because it is released over the course of an hour. Now, think about all of that energy being released in ten seconds. We're talking basically about a 5,000 watt heater trapped into a little space not designed to dissipate it. It's going to catch on fire. What's amazing to me about batteries isn't that they occasionally catch on fire, but how infrequently they do. Modern Li-ion batteries have an amazing amount of energy density.