Surface masking with polymer films, which have lower surface energy properties than metal or oxides , could potentially not only reduce the electrolyte leakage, but also control the reaction area more precisely. Kapton TM (polyimide) film was chosen as a masking layer due to its excellent electrical insulation of protected areas and relatively good chemical resistance to battery-graded electrolytes, as it has been used successfully in in-situ X-ray diffraction experiments for batteries .