PC Pitstop is a website regarding the PC optimization and usage. So they have experimented with a laptop having Li Ion battery and made it burn by puncturing the battery which makes it explode in different times due to the different packing's inside it. In the real situation this happens with the faulty packing of the battery or due to the external circuit near the battery which causes it to damage. A trusted company would never manufacture such a faulty one, very rare chances it happens.
Generally a battery gets weakens after a 3 years of use in regular use, replacement is the best option instead of using the same old once.
Here is the video where they have experimented: