Kinda crazy but might actually work for continental flights over cooperative areas. Parachute the empty batteries down with some minimal steering mechanism to land them at regularly spaced depots, then ship them back to airports fully charged.
Turnaround time for planes is short enough that you’d need to do a battery-swap rather than a battery-charge anyway.
I'd like to see what a typical widebody's fuel drain over time is, but suspect a large share is the takeoff-and-climb portion of flight.
A winged battery which could drop away at ~FL20--30 or so and return to either the origin field or some secondary collection point might be all you need, rather than tossing batteries out the cargo bay throughout the flight.
I also suspect that most EV aviation will be shorter haul such that a large set of drops wouldn't be necessary.
You piqued my interest enough to go hunting - this StackExchange[1] question estimates ~19% of fuel is spent on initial climb-out to 30k feet for a 737-800 on a 5-hour LA->JFK flight.
Without doing hard calculations, it intuitively feels pretty marginal potential flight weight savings for the operational complexity it would add
Worth noting that EV aircraft flight segments are likely far shorter (100--500 km, maybe at a stretch 1,000 km, not the ~5,000 km of JFK->LAX), and cruise much slower (~100--300 knots, say), so climb-out would be a proportionately larger share of the energy budget.
And ditching 20% of your energy storage mass immediately on attaining altitude would still be a considerable savings for the remainder of the flight as that mass doesn't need to be kept aloft.
EV aviation (and aviation itself) is a battle of thin percentages. EV aviation itself has relied strongly on materials advances (advanced fibre composites), and reducing crew (ultimately: autonomous piloting). The need for cabin crew for safety reasons remains, and would be a significant hurdle. The extent to which non-revenue occupants and payload can be minimised likely plays a huge role in any eventual success. A 19% reduction is nothing to be sneezed at, if it can be achieved without significant other compromise.
Turnaround time for planes is short enough that you’d need to do a battery-swap rather than a battery-charge anyway.