Why laptop batteries explode

Nickel Cadmium were the first rechargeable batteries manufactured for laptops. They were relatively inexpensive, had high output and versatile, because they could be used in a wide variety of products. Lithium Ion type of batteries has become the most popular for laptops since the memory effect has been eliminated, and much lighter than the other two in weight. However, the market price is also the highest. Laptop batteries may explode if left overnight all the time while charging. The laptop should be turned off occasionally. Exposure of laptop battery to heat, short-circuit, or factory defects.