Batteries are cylindrical because it’s the most efficient shape to make them in. There is a central electrode with the electrolyte around it. By making it cylindrical it’s distributed evenly. Imagine having it square, then in the corners the layers would be thicker than on the sides.
So that explains why the cells and normal AA batteries are cylinders. So why not have a 9 volt cylinder? That’s because the chemistry used for alkaline batteries produces 1.5 volts. A single cell, regardless of size, only produces 1.5V. So how do you get 9V out of a 1.5V battery? By putting 6 of them in series. 6 x 1.5V = 9V.
Wait until you see this:
https://brokensecrets.com/2010/12/20/9-volt-batteries-contain-6-aaaa-batteries/
I took apart a lot of batteries as a kid. The nine volts never had batteries like this inside them.
Since seeing this picture I have disassembled about 50 nine volts looking for this and have found about 3. Some full of coin cells too.
Edit: I should say it was years ago I first saw this picture. I haven’t disassembled 50 batteries in the last 2 minutes
I reject your edit and substitute the original assumption
How many batteries can you disassemble in 2 minutes? I’m starting the timer… NOW! Go!
The carbon-zinc ones never do, but the alkaline ones do, the ones I opened, anyways ( a few decades ago )
Some have stacked flat cells IIRC.
some do, i have dissasembled some of them to look like this. not all of them though
And A23 cells have eight LR932 button cells inside
https://en.wikipedia.org/wiki/A23_battery
Could have about 1/3 more charge if they were solid.
Why aren’t they?
Because it’s a 9 volt battery.
Batteries are cylindrical because it’s the most efficient shape to make them in. There is a central electrode with the electrolyte around it. By making it cylindrical it’s distributed evenly. Imagine having it square, then in the corners the layers would be thicker than on the sides.
So that explains why the cells and normal AA batteries are cylinders. So why not have a 9 volt cylinder? That’s because the chemistry used for alkaline batteries produces 1.5 volts. A single cell, regardless of size, only produces 1.5V. So how do you get 9V out of a 1.5V battery? By putting 6 of them in series. 6 x 1.5V = 9V.