How do I recycle old MacBook Pro batteries?
The disposal and/or recycling of batteries will differ depending on your local jurisdiction, namely because of local laws.

In some jurisdictions you can take your old electronic equipment, including batteries, to any Apple Retail Store. The local store will ensure that it will be recycled in a responsible manner.

Based on your profile, I see you're based in Germany. Germany is one of those places where Apple will happily take your batteries.

For more info, see So einfach wie Apple Produkte sollte auch ihr Recycling sein1.


1 The UK english version of the above referenced page is: Recycling an Apple product is as easy as it is good for the planet.