Lithium is a very reactive alkali metal and is usually only found in metallic form in laboratories. It can be pulled from lithium batteries with a little bit of force and a pair of pliers.
It’s a good idea to have an air-tight container filled with methanol to store the lithium, as it will quickly corrode in the air.
Grab a fresh lithium battery (used ones won’t work) and carefully peel back the outer casing of the battery to explode the core. It’s easy to accidentally short out the battery, if you do you should submerge it in water to prevent fire or an explosion.
Once you have peeled off the outer casing, unravel the core and discard the plastic sheets and electrolyte. There should be a thin strip of dirty lithium metal; you can wash it in methanol to clean it. Store it in an air tight container to prevent it from corroding.
To test that this is lithium, cut a small piece off and drop it in water, it will react violently giving off hydrogen gas and creating Lithium Hydroxide.