Influence of the primary ZnCl2 intercalate on electrochemical biintercalation of H2SO4 into graphite

The aim of this paper is to investigate the mechanism of the subsequent intercalation of H2SO4 into ZnCl2-graphite intercalation compound (ZnCl2-GIC). The X-ray diffraction analysis (XRD) and two electrochemical methods (cyclic voltammetric and galvanostatic measurements) were used to investigate the transformation of the starting ZnCl2-GIC to the ternary ZnCl2-H2SO4-GIC. Based on XRD patterns it is concluded that ZnCl2-H2SO4-graphite biintercalation compound (ZnCl2-H2SO4-GBC) and stage-1 H2SO4-GIC are formed on attaining the potential 0.9 V. If the electrochemical oxidation of ZnCl2-H2SO4-GBC is continued above the mentioned potential, the reaction between the primary and secondary intercalate takes place. The mechanism of the reaction is discussed based on electrochemical and structural data. (C) 2003 Elsevier Ltd. All rights reserved.