I'm not aware that Apple provided a longer-term battery option. But the only way to know with certainty is to remove the battey you now have and look for its specifications and model number.
As for your iBook you need to know it's model ID. Open System Profiler in the Utilities folder. The information will be displayed in the right side panel of the opening window. I can decode from that. Alternatively, if you know the serial number (displayed in About This Mac) then you can enter it here for the information.
One of the details of consideration that make a difference
would be the size of the Display; as the computer with a
14" LCD generally also has a faster processor than the
same model year build in a 12" display. Also the 14"
model is more likely to have a SuperDrive, not a Combo.
•14" ibook model ^
•12" ibook model ^
Notice there are white iBook G3 computers, also white G4.
The replacements listed at site linked below will work.
So when looking into a site such as this, be sure to check
the correct one (and display size) to check for a match:
The number of cells would only matter if you were into
taking them apart & rebuilding them. Not buying retail.
Good luck & happy computing!