EOS Energy (and not the solar panel company in the UK) is the only one I am aware of working on this technology. Here’s the gist. These batteries have a density of 400Wh/L for EV use, they are seriously safe (as in zinc and an electrolyte that has more in common with tooth paste than anything), they are so resistant to bursting into flames that they need nothing but a very very basic BMS, and they can be run to zero %. But, while with a 100kWh pack they can support a 175hp compact car, when you shrink things to motorcycle level and power needs, I think you will find that a 20kWh pack (double that of the proposed Empulse) would only support 35hp. This is where hobbyists found themselves only a few years ago with LiFePo4. The discharge rates just weren’t high enough to support a competitive street bike.
Now that last statement needs some explaining. If you run with the Tesla belief that EV need to be better than their gas counter parts to be successful then Zinc-Air isn’t the solution. But, if you believe in the Zero philosophy that EVs (at least elmotos) will develop on their own path, then these batteries would be a gold mine. Imagine an 18kWh 2011 Zero S. I say 2011 because I think the 2012 would be too powerful for the pack. Or a 16kWh Brammo Enertia would be perfect for this type of battery. But unfortunately, other than base model commuter motorcycles, these batteries don’t seem to have the oomph needed to help elmotos compete head to head with ICE bikes.
The rest of the story is that EOS has a lead acid battery technology that may be combined with the Zinc-Air for those high power demand moments. I suspect this may also be an area super capacitors could help out in.
Some very interesting articles I got my info from: