This is not fresh news but it is news to me.

Last year Tesla Motors was granted two patents related to the use of a metal-air battery backup for their lithium ion batteries to give journey ranges over 640 km.

Metal air batteries have much better energy density than Li-ion because the oxidant is obtained from the atmosphere rather than carried. BUT they can’t be recharged electrically so if you wanted to use it you would need to swap in, swap out once it was dead. I suppose the idea would be that you would normally be using just your Li-ion and would switch to the metal air when the Li is depleted. (Technically the metal air is used to continually recharge the Li-ion when in use so the car is still being driven by the Li-ion.)

Prime candidates would be zinc, aluminium and nickel.

Clean Technica article

Patent 1“20130181511”.PGNR.&OS=DN/20130181511&RS=DN/20130181511

Patent 2“20130187591”.PGNR.&OS=DN/20130187591&RS=DN/20130187591

I first heard about zinc-air batteries about 20 years ago but have never seen one.

Wikipedia has “Zinc-air batteries have higher energy density and specific energy (and weight) ratio than other types of battery because atmospheric air is one of the battery reactants. The air is not packaged with the battery, so that a cell can use more zinc in the anode than a cell that must also contain, for example, manganese dioxide. This increases capacity for a given weight or volume. As a specific example, a zinc–air battery of 11.6 mm diameter and height 5.4 mm from one manufacturer has a capacity of 620 mAh and weight 1.9 g; various silver oxide and alkaline cells of the same size supply 150–200 mAh and weigh 2.3–2.4 g.”

so as a battery it’s virtually useless as it can’t be used again??

looks like a red herring patent to me

wookiemeister said:

so as a battery it’s virtually useless as it can’t be used again??

looks like a red herring patent to me

Nah, it can be used again and reformed mechanically back at the plant, but can’t be recharged electrically.