For full disclosure, I'm currently trying to start a business to convert vehicles from Gasoline to Electricity. (Plug-In Motors Inc. www.pluginmotors.com) Our first vehicle is a Mustang Conversion. We are setting up our base vehicle to run 85 miles @ 55mph on a charge but are capable of setting up the vehicle to run 250 miles @55 mph per charge.
It's surprising to me that this would be such a big deal. When you consider the number of laptops that have batteries in them and no one is asking any similar questions. And if you consider the extended concerns with gasoline and gasoline engines, it's pretty obvious that an electric vehicle is much easier on the environment. First, AC Induction electric motors usually last about 10 times gasoline engines. So we could have 10 times fewer "engines" in the world even with the same number of cars. They are much smaller (about 10 times smaller when designed correctly for an electric vehicle) and much easier to make. If anyone has seen a gasoline engine plant you would understand how environmentally unfriendly that whole discussion is. Add to that the opportunity to eliminate the transmission, or at least much of it's internals, and just with these two components one is able to make up for any increase in land fill for the batteries.
Additionally, there are many options for the batteries even after the vehicle is finished with them. At Plug-In Motors, we expect that customers will use the batteries in our vehicles until they reach about 80% of their original capacity. Thus, if our original set up goes 85miles, at the end of their life cycle (expected to be between 2000 and 2500 cycles) the vehicle would still travel 68 miles at 55mph before needing another charge. If we are correct, then these batteries, while probably not adequate for the vehicle any longer could very easily be used for other needs. Specifically for power plants to charge at night so that they can load level between the night and day, or for second by second changes to peak demand. The value here is extra-ordinary as it could easily reduce our need for new powerplants by 30-40%. This isn't done today because of the cost of batteries is too high, but if the pack has already been used for 200,000 miles in a vehicle, being able to then sell them to the power plant can help pay for the next pack. Alternatively, if you live in a region where the power company charges more for electricity during the day than at night you can charge them at night and sell back during the day. Or, hook it up to your own solar cell and be "off the grid". Really there are lots of options before going to recycling.
As for the original question, It's my understanding that Ni-Cd (Nickel Cadnium) and Lead Acid batteries are very tough to recycle and are a real issue for the landfills. However, recycling is possible with both. Nickel Metal Hydride is somewhat easier and Li-Ion batteries are the easiest. Li-Ion batteries have no environmental downside like the Lead Acids or the Ni-Cd's which leach lead into the environment.
"Take that, you hostile sons-of-bitches!" -- James Coburn, in the finale of _The_President's_Analyst_