I thought I would bring this thread up to current as Voyageur mentioned using battery lead.
It has been my experience that many people purport to have done something, when in fact they have only read about it. I used to sell over 500 car batteries a year.
The old lead/acid battery, also known as the dry charge battery, is a dinosaur that has all but disappeared many years ago. A few may still be available for commercial applications.
With the advent of the wet charged or sealed battery many years ago, technology changed drastically. The old batteries were sealed with asphaltum, which could be heated and the plates extracted. A battery with a dead cell could have the plates in that cell replaced and the battery resold by rebuilders.
New batteries can only be opened by cutting the case open. Inside, you will not find lead plates, but rather grids which are individually enclosed in packets of some type of plastic envelope. If you take one of those grids and remove it from the envelope, you will find that it crumbles in your hand. It is not lead, but as others have said contains a variety of toxic materials. This is the reason why they are now classified as hazardous waste and must be recycled, and also the reason why you must have an old battery to exchange when you buy a new one.