Medals are awarded to the Commander after successful Raids on other Commanders, and successfully defending your Base from incoming Raids. Medals have no commercial use; they are simply currencies used to rank a player towards the Raid leaderboard.
The Superconductor 2000 requires you to have 1000 Medals in order to purchase it with Raid Chips.
28~33 Medals are won or lost for each Raid or Base attack.