US electric vehicle manufacturer Tesla Motors has filed patents which describe a combination lithium-ion and metal-air battery pack.
This hybrid battery pack would primarily use the lithium-ion side, drawing power from the metal-air battery pack only on extended journeys. Metal-air batteries, which use oxygen as an electrode, have a shorter lifetime when exposed to regular charging, but use more common elements like zinc or aluminium, reducing costs.
The patents also describe an operational mode where the metal-air battery would charge the lithium-ion battery, which powers the car’s systems. Such a hybrid battery pack could extend the range of cars like the Tesla Model S by up to 40%, allowing for 400 miles of driving between charges.
However, despite filing the patent, Tesla is expected to pursue lithium-ion for the forseeable future.