I found the new M12 High Output battery at the local HD. Let's take one apart and see how it compares to other M12 batteries.
For reference, I used an M12 soldering iron.

Details:
CP2.0: 26Wh tested, 24Wh rated. LGDAHD41865 cells
CP3.0: 35Wh tested, 36Wh rated. LGABHG21865 cells
XC3.0: 41Wh tested, 36Wh rated. Samsung 15M cells
2.5HO: 34Wh tested, 30Wh rated. Samsung 25S cells
XC6.0: 77Wh tested, 72Wh rated. Samsung 30Q cells