Absolutely not. Airplanes have to be aerodynamic, and it would be incredibly challenging to make the entire bottom portion of the plane something that can open

Absolutely not. Airplanes have to be aerodynamic, and it would be incredibly challenging to make the entire bottom portion of the plane something that can open up and fit a giant battery. Never mind the weight of the whole system plus battery. The whole idea is absurd and completely impractical.