Carefully said, this is an IATA (International Air Transport Association) regulation that all member carriers have adopted. All Lithium based batteries including those powering your camera, smart phone, laptop, etc must be part of your cabin baggage. The reason is that they do occasionally burst into flames and you don't want that happening in the cargo hold where it can't be detected. Li-on fires are thought to have been the cause of at least one cargo plane crash.
Other kinds of batteries are okay to put into your checked luggage.