If you are talking about Activation Energy for Ionic conductivity, you have to measure the conductivity as a function of the temperature. Then, you can use arrhenius type equations to fit the date and get the activation energy. I have worked with some NASICON solid electrolytes too.
For more information take a look in the following studies:
Article A new NASICON lithium ion-conducting glass-ceramic of the Li...
Article Numerical comparison of usual Arrhenius-type equations for m...