The swelling is the result of heat. It causes the solid O2 in the cell to turn to gas. If it gets hot enough, the oxygen ignites. Laptops have cooling fans. If the device is left on and wrapped up in a bag, the fan cannot do its job. Even when using a laptop - make sure the fan is not blocked. The biggest problem with Lithium is that people don’t take the time to learn how to care for them.