In this work, the behavior of composite graphite electrodes comprising synthetic graphite flakes in solutions based on a 1-methyl-1-propylpiperidinium [bis(trifluoromethylsulfonyl)] imide (MPPpTFSI) ionic liquid (IL) was investigated, using in situ Raman spectroscopy with microscopic lateral resolution, in conjunction with cyclic voltammetry. Both pure IL and IL solutions containing a LiN(SO2CF3)(2) (LiTFSI) salt were studied. Upon cathodic polarization, the IL cations (MPPp+) are intercalated. This process is irreversible in a pure IL solution. When the solution comprises both IL and a Li salt (LiTFSI), the graphite electrodes can intercalate simultaneously the IL cations MPPp+ and the Li cations at potentials similar to 0.5 V and below 0.3 V vs Li/Li+, respectively. The graphite electrodes become passivated due to the presence of the Li salt by the formation of surface films, which are Li-ion conducting, but electronically insulating. Hence, upon consecutive voltammetric cycling, the IL cation-intercalation is suppressed, while reversible Li intercalation becomes the dominant process. Raman spectroscopy enables one to distinguish among the various processes in these systems. (c) 2007 The Electrochemical Society.