First of all, what do you mean "to see if the material reacts as a whole or as different components with Li or Na ions"? I don't think that galvanostatic cycling will be able to tell you much about the distribution of certain reaction within a material. For that you would need to use other physical characterization techniques such as TEM.

The galvanostatic charging curve will tell you at which electrochemical potential certain reactions take place and how much charge is involved. So you should known at what potentials you would expect certain reactions to happen.

If you have a material which can act as a conversion material, it might have a higher electrochemical potential of reduction compared to the alloying reaction. Do you mean to say that you are starting with a conversion electrode? In that case you might have the reaction:

MOx + 2Li+ + 2e- ↔ M + xLi2O (M = metal). In theory it should be possible to further reduce the metal and form a Li-M alloy.

You could try to take the differential of Q vs V (charge vs voltage) which you get from the galvanostatic charge/discharge, which will show you better at which potential certain reactions occur. If the potentials at which the reactions occur are separated enough, you might be able to get the relative charge associated with one reaction compared to the other.

Another method which you can use is cyclic voltammetry with a slow scan rate (1mV/s or lower).

I think your suggestion of having a look at the curve of a galvanic experiment, where you measure the potential against time/charge is a suitable way for distinguishing between those two types of materials. (If I read it correct which types you mean)

In detail:

1. In the case that the 'whole material reacts' I believe that you mean the Li/Na is solutable in the material over a large composition range. In this case the chemical potential is changing smoothly over time and you get a smooth change of the potential.

2. In case that there are specific narrow phases formed (examples are Sn or LFP for Lithium) the chemical potential stays the same from the point on the first bit of the phase (e. g. SnLi) is formed up to the time when the whole material is converted to this phase. Therefor you get steps in the potential you are observing over time.

The question was aiming at a distinction of alloying and conversion type materials as these terms are commonly used to describe secondary LIB electrode materials (e.g. Chem.Soc.Rev., 2009, 38, 2565–2575).

As i understand both these material types undergo significant structural changes and volume expansion upon lithium uptake and have increased capacity compared to insertion type materials.

So while the discrimination to insertion type materials is evident the distinction between conversion and alloying type material is not clear to me.

If i understand susann correctly the fact that several intermediate phases are formed upon lithium uptake (corresponding to several reaction plateaus) enables one to attribute the term of conversion type material. In the above stated publication the reaction of Sn and Li is however characterized as an alloying type reaction.