In its discharged state, the Pellion battery has its lithium ions sitting snugly inside the cathode. The magic happens when the battery is charged for the first time, and the lithium ions travel from the cathode and deposit as a layer of lithium metal on the copper anode. The first charge is carried out in a state when the battery is completely sealed from the outside environment, and thus the newly formed layer of lithium metal is protected. This configuration is called “zero-lithium” or “lithium-free.”
“It is quite an impressive feat,” says Venkat Viswanathan, a battery expert at Carnegie Mellon University.