The car-batteries of the near future

For those wondering about power during whatever timespan the solarpanels aren't doing their thing, the Pocket-Lint site has a summary of some 2014-19 research on "batteries". By "batteries" we should understand arrays of whatever stores kilowatthours and rations back watts at a steady rate. And we're expecting to REcharge them. This means chemical electrodes and capacitors.

I expect my Venus-region batteries degrade slowly (on par with aeroplane-maint'), are light weight, recharge at a reasonably fast rate, and are cheap to make in space or in low-pressure CO₂ or in an acid bath. For my aeroplane turbines I also want them to perform in high temperatures (electric car batteries demand 60 C), and to discharge VERY fast on demand. We don't care about flammability in oxygen where there is no oxygen.

This does rule out the "Air Battery", like aluminium and zinc... until we get a CO₂-burning version, in which case we'll need them not to explode too.

A power cell provides energy when ions move from the negative anode to the positive cathode; when the cell recharges, the ions move back. For the ions: lithium, the lightest metal (except hydrogen) and also reactive, is the standard choice. In Pocket-Lint's article, battery management and temperature modulation segments assume lithium.

Some of the research is to get more lithium in the right place, without exploding. The present standard is LiC₆. Lithium-sulphur is over-hyped. We are also witness to grand promises about All-solid-state... but at least the producers admit it. Dual Carbon was another lithium tech hyped in 2014; but I don't know what has come of that. A present serious alternative is Li₁₅Si₄.

For non-lithium solutions IBM is talking "seawater". That means brine, to chemists. Besides the obvious saltwater, brine is mined for magnesium, potassium, and bromine; when people talk seawater in this context, they often mean magnesium. Sodium is also mooted (UPDATES June 2020, December).

Another option (for a moving vehicle) is the capacitor. These charge and discharge (much) faster than do chemical powercells. You would just need a LOT of them - they'd be used alongside the solar panels and chemical cells.

Or, you could use graphene in your anodes and have a capacitor-cell hybrid. UPDATE 1/2/2021: Post-graphite is good for sodium too.