Such batteries are not really marketed. The economic case for them relies on the market for lithium being saturated — but the market is not saturated. You can't

Such batteries are not really marketed. The economic case for them relies on the market for lithium being saturated — but the market is not saturated. You can't make a profit selling lithium alternatives when we're not presently close to being out of lithium, even if we might hit a supply crunch at some point. Gelion in Australia makes a zinc-bromine battery with an 87% RTE per their IPO filings. I've been watching them closely, but I've been hesitant to invest in a company whose products probably have years before they're in serious demand. Most flow batteries are well below 87% RTE.