The zinc-air article is on
The zinc-air article is on point about Li system costs and economic advantages of zinc systems; however, until the electrical round-trip discharge-charge efficiency is improved zinc-air systems will be limited to markets where round-trip energy efficiency is not particularily important. For EVs & PHEVs round-trip energy efficiency is important.
Best zinc-air technology known (and have not followed recent investigations by new start-ups) is about 64% DC-DC electrical efficiency and in systems with active charging of the whole cell it is more like 55%. Until a technical breakthrough on the overvoltage for the oxygen electrode is created zinc-air systems will be stuck to more limited markets.
Note: These lower efficiencies can be acceptable in some cases for wind and solar energy storage.