Dear Jiang Yang,

basically, a ragone plot should be derived from constant power experiments. So this would be the way to go if possible. Of course, you can derive similar data from galvanostatic measurements by calculating a mean voltage Vm for each applied current I and giving the mean Power Pm as Pm=I x Vm and Energy E as E = Pm x t . Or, if your measurement device gives you a value for the energy exchanged with the device under test, then you can yust divide that value by the discharge time to obtain Pm.

Of course, the most important thing will be to describe well how you obtained your (pseudo) Ragone Plot.

Best wishes

Tobias Bach