Influence of polymeric binder on the stability and intercalation/de-intercalation behaviour of graphite electrodes in non-aqueous solvents

Cyclic voltammetric and scanning electron microscopic investigations on a highly-packed, crystalline, graphite electrode (HPC) and on a polypropylene composite graphite electrode (CPP) containing 20 wt.% polypropylene binder indicate that the latter has higher mechanical stability and higher electrochemical intercalation/de-intercalation activity. This holds for the intercalation of lithium (Li+) and tetrabutyl ammonium (TBA+) cations from dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF), as well as for the intercalation of perchlorate (Cl04−) and fluoroborate (Bf4−) anions from propylene carbonate (PC) and acetonitrile (AN). There is a linear correlation between the threshold potential for the beginning of intercalation (Eth) and the intercalation/de-intercalation efficiency (IDE) for cationic intercalation. In the case of anionic intercalation, two distinct linear relationships for HPC and CPP electrodes are observed. Competitive oxidation processes reduce the IDE on the HPC electrode.