There are still orders of magnitude between current batteries and the theoretical hard cap. Current batteries throw away enormous capacity due to the safety constraints in preventing thermal events. Lots of folks looking at how to solve that problem.
And what then? In term of energy contained in atoms, current batteries are many, many orders of magnitude away from the theoretical maximum energy density of matter. (And so is liquid hydrocarbon fuel.)
> There are still orders of magnitude between current batteries and the theoretical hard cap.
Not at all. Existing cathode materials have a theoretical coulombic capacity of about 200 mAh/g (mostly less than this value, a few more have more). So for a 45g cell like an 18650, you are looking at 9,000 mAh maximum in the impossible world where your battery is 100% cathode, no anode or electrolyte. Those cells are already > 3000 mAh, so there is no way there are orders of magnitude between current batteries and the hard cap.
On the contrary, for contemplated chemistries the practical hard cap is probably less than 2x current capacity/weight values (since you need a significant amount of anode and electrolyte in practice), and almost certainly less than 3x.
> Current batteries throw away enormous capacity due to the safety constraints in preventing thermal events.
If by "current batteries" you mean current chemistries like Li-ion and existing and contemplated cathode materials, then this is not correct. The batteries have essentially the ideal material ratios within the existing manufacturing capability. That is, if you were willing to have a much less safe battery with the same materials you would gain almost no capacity. The main concession to safety is when a safer cathode material is chosen, like LiFePo over cobalt or whatever.
Batteries don't need to hit theoretical maximums, they only need to get within the ballpark of liquid fuels (maybe .25-.5x)? This will basically require the use of air in the reaction, since one of the reasons liquid fuel can store so much energy in such a compact and lightweight form is that it doesn't require storage of one of the primary reactants (oxygen).
last time i check liquid fuel has 50x the energy density of battery.
so to get to /4, you would need a 12x increase.
>since one of the reasons liquid fuel can store so much energy in such a compact and lightweight form is that it doesn't require storage of one of the primary reactants (oxygen).
the main reason is the covalent bond is stronger. using air will only double the energy density for fuel( 1x fuel instead of /2 fuel /2 oxygen.)
Also important in some applications, such as aerospace, is that liquid fuel depletes in weight as you use it. Batteries are enough of a closed system that you still have to carry all of the weight around even when you're out of power.
And what then? In term of energy contained in atoms, current batteries are many, many orders of magnitude away from the theoretical maximum energy density of matter. (And so is liquid hydrocarbon fuel.)