Think about the materials involved. What material stores all this energy, which one assumes is inert and room-temp? And if it's not inert/room-temp, what material contains the other material?

In each case, how much mass is needed of each - to store, and to contain? Noting also that the more mass you need of the energy-bearing material, the more you will need of the other. Can that mass be compressed into 4 cubic centimeters?

I personally have no idea, but it's sure sounding impossible.

Volume of a AAA battery = ~3.85 cm^3

And let's give it a density of the densest elemental metal (Osmium), at 22.6 g/cm^3

Assume the battery stores pure energy (I know, I know). So E = mc^2, which is like 8.99 x 10^16 J / kg

So that battery would hold about 22.6 g/cm^3 * 3.85 cm^3 * 8.99e16 J / kg = 7.8 * 10^ 15 joules = ~2.2 TWh, about a trillion times more than a normal AAA battery.

Doing some LLM-assisted sleuthing, a large cruise ship can use over 80,000 gallons of fuel a day [1]. A bit of searching indicates marine fuels have a density of approx 39 MJ/L (I'm using volumetric density for consistency), so 80,000 gallons * 39 MJ/L = about 1.1 x 10^7 megajoules = 3.2 GWh.

So a 2.2 TWh AAA battery could power that ship for 671 days.

Of course, the practical physics here are nonsense and there are obvious safety considerations associated with your AAA-sized nuclear weapon, but maybe that's what the author was getting at?

[1] https://blog.windstarcruises.com/how-much-fuel-cruise-ship-u...

The smallest terminal you can connect to a AAA battery is the same diameter as 00 AWG copper wire.

Provided that the engine has 100% efficiency and can turn 176MW of electricity into torque, to safely run power it needs through that 00 AWG wire, the battery would need to provide a voltage of at least 70 kV.