As others have said, matter doesn't change. As I understand it, lithium crystals form inside the battery and eventually short the battery out. The lithium mov

As others have said, matter doesn't change. As I understand it, lithium crystals form inside the battery and eventually short the battery out. The lithium moves between the anode and cathode to release/store energy. I think when it's locked up in a crystal it isn't free to move and reduces the battery capacity as well.