I think, apart from finding better Batteries altoghether, we should build multi-tier batteries inspired by biology. Humans have bloodsugar, sugar in the Liver and then fat. All of them have their respective properties with availability and amount. This way, engineering tradeoffs could be allocated much more fine grained. For example, a while ago I read about a startup building an energy storage where they heat up large amounts of sand to store the surplus of renewables. This could serve analogous to the fat in humans.

Biological power is marvelous, but really inefficient. All that sugar and fat in entire human body only generates 50-150 Watts.

Humans do that because we're big and extra complicated. The closest analogue is probably a hybrid car, though ideally you'd want one that can create synthetic fuel from its battery. But I suspect cellphones are properly analogous to e.g. bacteria that have much simpler energy storage.

The good news is that humans already exist, so you can already use them. It will give them something to do with AI replacing them elsewhere.

You might not like the efficiency of that type of battery, though.

I look to a future of regularly servicing the immune system of my battery.

I think I've heard of sodium, lithium hybrids. But that's only 2, what's the fat? Gasoline, LPG hybrid? Shit gets expensive fast. Probably 2x cost of just a sodium or ion EV? The human body is too amazing.