The understanding of the formation and movement of charges inside solid polymer electrolytes is a critical point of the research for the development of better lithium-ion batteries (LIBs). In order to facilitate the understanding of the charge distributions, the Kelvin probe force microscopy with a reliable statistical data analysis approach has been used. As poly(ethylene oxide) (PEO) is a material used as an electrolyte in LIBs, the PEO and its salt compound with lithium perchlorate (LiClO 4) were investigated with this approach. The transient formation and movement of internal potential and simultaneously the charge distribution were investigated with respect to time under biased and unbiased conditions.