Lithium ion batteries are the de facto choice for most plug-in...

Lithium ion batteries are the de facto choice for most plug-in hybrid and electric vehicle manufacturers, but at least one company thinks that zinc-air batteries are a better option. Advanced Power and Energy Sources Transportation (APET), a small Taiwanese startup, has developed a zinc-filled pouch that fits in an EV's fuel cell stack along with a demo car outfitted with the zinc-air fuel cells to prove that it works.

Zinc air has a number of advantages over lithium. The fuel cells are both lighter and cheaper ($3,600 for a zinc air fuel cell stack vs $15,000-$20,000 for lithium)-- a big advantage, since high lithium battery prices are preventing PHEVs from entering the mainstream.

There are some downsides. Zinc batteries can't store as much energy as lithium, and they wear down after only a few charges. But APET is trying to work around the problem with an easy-to-remove zinc pouch that turns white when it's spent. And once the the batteries are decommissioned, leftover zinc can be turned into fuel or chemicals for other applications--i.e. zinc oxide sunscreen.

Lithium certainly has the advantage in terms of production capacity--a slew of companies in the US and elsewhere are gearing up to produce large quantities of lithium ion batteries--but zinc also has a number of companies on its side, including ReVolt, PowerAir, ZPower, and PowerGenix.

So who will win the battery wars? It's too early to tell, but zinc proponents will have to be extremely vocal if they want to drown out the voices of the growing lithium brigade.