The potential plateau appears at the point where charging or discharging leads to formation of a new phase on one of the electrodes. The potential will remain the same as long as both initial and final phase exist on the electrode.

If charging goes through formation of the non-stoichiometric compound and gradual change of its composition, the voltage will also gradually change with SOC.

In the real systems this behaviour can be not easy to see due to the kinetics of the electrochemical processes, so dQ/dV plots are more convenient. The voltage plateaus will transform to more or less pronounced peaks after differentiation.

 Hi Alexander,

Thank you so much for your response. Just a quick clarification, when you say different phases coexist, in order words, are these the oxidized and reduces phases of the active material used?

Thanks again

Shinjita,

Yes, you are right.

As from my reflections the flat plateau means local coordination of transition metal ion remain unchanged, once we have phase transition or change in oxidation state, it changes abrupt

If we have e.g. vacancy-Mg ordering in Mg batteries, it changes gradually, so this can be analogue of change "through formation of the non-stoichiometric compound and gradual change of its composition"

Another things from Alex I do not know, but suppose he knows well what he is talking about)