context: This simple, yet methodical sonication method can be applied to evaluate the surface stability of inorganic materials. In particular, the agglomerated secondary particles require a dispersing process to prepare samples for the TEM analysis. In addition, an extended sonication may be necessary in the cycled electrodes because of the binder usage. Our results have also shown that the surface of layered oxide materials can be easily influenced by the sonication method. Furthermore, our previous study also demonstrated that the cathode surface can be transformed by simply soaking layered oxide powders in organic solvents, including typical electrolyte solvents. With the inherent surface fragility of Ni-rich oxide materials, it is crucial to take cautions in preparing samples for characterization. Alternatively, many studies have applied focused ion beam (FIB) to prepare thin samples for TEM experiments. In this case, the chemical and structural information around grain boundaries can be protected for TEM analysis. However, it is not clear how the surface region may be influenced by the typical FIB coating protection and sample handling.