This type of battery seems quite easy to DIY. Cheap materials, relatively safe, not flammable.

You can either maken individual cells or make a flow battery which is theoretically infinitely scalable. You’d be limited by the size of the electrode in how much power this battery can deliver.

Has anyone here tried to make a flow battery? And did you have any success with powering something large and energy consuming?

I guess it would also be possible to make a battery out of old buckets, carbon fiber mesh and separator material such as glass fiber.