So, this would involve anodizing the steel in Nitric Acid to make a suitable anodized surface (that wasn't just rust). I'm not sure what the anodizing bath needs to be for brass. I wonder what they use?

This sounds like a great thing to release an instructable for. I'd be happy to give some home chemistry and construction a try to build a big battery. However, I question whether all this can really be done safely with "home chemicals". Many home chemicals are hardly safe and have some serious potential for harm if you find yourself breathing fumes, burning, heating, boiling, or handling them. I wonder at potassium hydroxide in sufficient concentration to be a useful electrolyte. Anything >2% is considered caustic.

I think the biggest problem with this, based on the paper - is the fact that to anodize the steel, you have to heat it to 600+ degrees F for an hour, in an argon or hydrogen atmosphere.

How the heck you do that "at home" won't be easy. Maybe take an old oven (outdoors), stick it on the cleaning cycle, then put the steel electrodes in a sealed pyrex container (?) filled with argon/hydrogen?

Maybe fill a steel pipe capped off with hydrogen, then heat that in the oven (where the inner surface becomes the electrode) - that might actually work ok (if a bit dangerous). Though how to seal it properly to prevent the hydrogen from leaking out might be a challenge.

If the pipe idea could be worked out - then a series of brass rods or plates could be used suspended (and electrically insulated) from the steel pipe, to form the battery electrodes (similar to how a regular alkaline or carbon-zinc cell is constructed).

Hydrogen is a pain to work with. Other than being explosive in air, it leaks unless the seal is near perfect. On the flip side, it's easy to obtain via electrolysis. If argon is acceptable it would be much easier to work with. The pdf reads like a mixture was used. I have done some work @ 1300C where we needed an inert atmosphere, so we plumbed an argon tank to the furnace and ran it at a slight positive pressure.

This has the potential (pun intended) to be a big deal in wild world of battery tech. BUT I'd like to see the next phase if, or more hopefully when, they can demonstrate a battery with enough capacity for a home. And provide DIY instructions on how to build. Still very exciting nonetheless.

More information:

http://pubs.acs.org/doi/suppl/10.1021/acsenergylett.6b00295/...

Interesting discovery, however the energy density of such a battery would mean it couldn't ever be used to replace current lithium cells due to weight/space constraints. Might have a niche somewhere if gets to commercialisation stage?

Stationary storage doesn't care about weight and doesn't care a whole lot about space, so it sounds like a decent fit. Grid storage is becoming very important and useful as inconsistent renewable power (wind and solar) becomes cheaper and more common.