Why does the battery of a mobile phone/notebook explode?

Compared with other secondary battery technologies, lithium-ion batteries are lighter, cheaper, and have higher energy density. It has become an important form of rechargeable batteries today, and everything from mobile phones and laptops to cars and commercial jets uses lithium-ion batteries. But this kind of battery has a small problem—not only short-circuit, but also fire and explode. Please see the analysis on the Gizmodo website below: The reason why lithium-ion batteries tend to explode is due to a process called thermal runaway. In essence, thermal runaway is a positive energy feedback cycle: increased temperature will cause the system to heat up, and the system will heat up and increase the temperature, which in turn makes the system hotter. Thermal runaway is a very common phenomenon. Thermal runaway may occur in a large number of physical and chemical processes from concrete curing (which releases heat) to star explosions (supernovae are the product of thermal runaway). There are many reasons for the thermal runaway of lithium-ion batteries. For example, when the two ends of a 9V battery are bridged by a coin, the tearing of the membrane that separates the negative and positive electrodes of the lithium-ion battery will cause a short circuit, and the short circuit will often cause thermal breakdown. The reasons for the fire of the lithium ion battery include: the ambient temperature exceeds 60°C, often overcharge, and unauthorized modification of the shell. Regardless of the reason, it is the cobalt oxide chemical in the battery that undergoes this reaction. Joe Lamoreux, vice president of research and development at Valence Technologies, explained: If you heat this chemical to a certain temperature, it will start to heat up by itself, and then develop into fire and explosion. In some cases, the release of pressure from this organic electrolyte can cause the battery to break. If exposed to a high temperature environment, or encounter sparks, it may also burn. Although this uncontrollable reaction does not happen often, the number of lithium-ion batteries is too large, which makes us feel that such accidents often happen. For example, in 2006, almost all important notebook computer manufacturers—Apple, HP, Toshiba, Lenovo, Dell and other companies—have recalled products after receiving reports of a small number of batteries overheating. Apple alone recalled 1.8 million Powerbooks and ibooks after 9 valid reports appeared. More importantly, the size, configuration, and number of cells of the battery all affect the intensity of thermal runaway. Small battery packs (such as those on digital SLR cameras) have only a few battery power sources, so the chance of thermal runaway spreading from the problematic battery unit to other units is relatively low. The huge battery packs of the Boeing 787 are another matter: they are housed in a sealed metal box and cannot emit waste heat. As a result, when one battery cell is hot enough to ignite the electrolyte, the remaining battery cells will quickly follow. Enter. But you don’t need to worry too much. Your notebook is not a ticking time bomb. As long as some maintenance is done regularly, the lithium-ion battery will work safely and reliably. Lithium ion has a short lifespan and can generally last two to three years (whether you use it or not). Because of this, all lithium-ion battery packs should be replaced every 36 months or so. Moreover, whenever the power drops to 50%, you should be able to charge it. Lithium ions have no memory effect, but too low a voltage can severely damage them.