Another battery chemistry for those who want to DIY, this is cheaper than zinc but slightly less energy density.

Iron ion Air Battery-Rechargable:

Negative Electrode:
Iron powder, Ink solution of Graphene Oxide coated Magnetite (can be made by lookng up Robert Murray Smith's videos), addition of garlic based carbon and between 0.1-0.9%wt ABtype Metal Hydride material. Make a binder out of garlic oil (from fresh garlic) and 2-5%wtPTFE or other binder and pasted onto a conductive electrode mesh. Addition of FeS and BiS from 2-10% wt can improve cell life time and reduce hydrogen evolution.

Positive electrode (two of these per 1 negative):
conductive porous scaffold material, graphitized carbon with high surface area carbon based ink, addition of NiO, Ag powder, CoO for ORR and OER, coat the scaffold in the ink, freeze dry, then photonically "sinter" by flashing with a high flash xenon bulb. This reduces the oxygen and exfoliates the carbon lattice-increasing surface area.

Electrolyte: Liquid or gel

Gel: 1.Sodium polyacrylate with water and KOH
2. PVA,water,KOH
3. other gel type of choice

liquid: NaOH or KOH and water, possible addition of 0.1-.4%Li(OH) for increase in capacitance

The gel version of these with a GANS paste outer layer for the oxygen side may scavange CO2 and prevent caronization of the air-based electrodes. Either this, or the batteries can be used in tandem with an electrolysis cell is used and the "waste" oxygen is used to keep the O2 concentration higher than the CO2 concentration at the surface of the air electrodes. These batteries are relatively cheap, easy to recycle, easy to manufacture, and reasonably powerfull at 1.28-1.4V and 400-900mAh\g average