Surface transformations of polypropylene-graphite composite electrode material during intercalation/de-intercalation of monovalent cationic and anionic species from non-aqueous solvents

Surface transformations of a polypropylene-graphite composite electrode after intercalation/de-intercalation of monovalent cationic (Li+, Na+, K+ and TBA+) and anionic (ClO4− and BF4−) species in different non-aqueous solvents are compared under otherwise identical experimental conditions using scanning electron microscopy (SEM). Li+ and TBA+ cations, as well as the BF4− anion, display fairly high intercalation/de-intercalation efficiency and a high level of surface roughening due to the removal of horizontally-oriented graphite plates in the initial phases of cycling. Edge planes are found to be responsible for the highly reversible intercalation/de-intercalation behavior and the cycleability.