Evidence of graphite blister evolution during the anion de-intercalation process in the cathodic regime

Ion intercalation inside graphite crystal is a well-established method for graphene production. Pure acid electrolytes swell the stratified crystal structure and a gentle sonication disperses graphene flakes inside the solution. In view of a better environment-friendly graphite delamination procedure, diluted electrolytes can represent a viable option. Unfortunately, the presence of solvated ions between graphite planes induces oxidation of carbon atoms and the following development of gases in the buried layers of the crystal. Being not permeable, graphite entraps the gases that deform the crystal by producing characteristic bubbles called blisters. The latter represent a detriment of the original specimen and influence the quality of the produced graphene flakes. Here, we will address key properties of blister formation and growth by proving, in particular, that blisters evolve when the applied electrochemical potential value is reduced (cathodic regime), i.e. after the intercalation, conversely to what has been believed for long time. This finding requires a refinement of the current anion intercalation interpretative model.