Dilute Graphite−Sulfates Intercalation Stages Studied by Simultaneous Application of Cyclic Voltammetry, Probe-Beam Deflection, In situ Resistometry, and X-ray Diffraction Techniques

Abstract

This paper describes the stoichiometry, kinetics, and electronic resistivity of dilute graphite−sulfates intercalation compounds (stages pristine toVIII) obtained during electrochemical oxidation of graphite in 4M H2SO4 solution. The stoichiometry of the reaction was determined by the use of cyclic voltammetry and in situ XRD. Dilute graphite-sulfates phases are formed continuously as solid solution in the graphite matrix. The electronic resistivity of the composite graphite electrode as a function of potential depends largely on parasitic reactions, i.e., partial oxidation of graphite particles. The ionic flux of the HSO4 - species across the electrode−solution interface was traced by deflection of a probe-laser beam (“mirage”, or PBD technique) measured simultaneously with cyclic voltammetry. Convolution of the resulting deflectograms, measured at different distances from the electrode, allowed the calculation of diffusion coefficient of the active species in solution. Basic electroanalytical features of Li-ion intercalation into graphite from Li+-containing aprotic electrolytes are compared with those for HSO4 - in aqueous 4M H2SO4.

Analysis of Conjugated Polymers Conductivity by in situ Electrochemical‐Conductance Method

“…These electrodes are optically transparent, and the conducting properties of ITO let to study the simultaneous changes of optical and conductive properties with the redox changes of the films, induced by potentiodynamic and potentiostatic experiments. In‐situ resistometry was presented as another alternative to evaluate the conductivity of thin electroactive films . In this technique a 6 or 10 electrode arrangements are required.…”

Carbon‐Based Materials for Lithium‐Ion Batteries, Electrochemical Capacitors, and Their Hybrid Devices

“…The formation of stages II, IIL (a transition stage between stage II and stage III), III, and IV were identified from experimental electrochemical curves [80,81] and were confirmed by X-ray diffraction and Ramans pectroscopy. [79,[83][84][85] Twof actors determine the formation of stages during Li intercalation into graphite:o ne, the energy required to expandt he van der Waals gap between two graphene layers; two, the repulsive interactions between the guest species. Therefore, compared to ar andom distribution of Li in the graphiticl ayers during the charge process, Li ions prefer first to occupy van der Waals gaps with ah igh Li ion density to reach an energetically stable state.…”

Interpenetrating organic conducting polymer composites based on polyaniline and poly(3,4-ethylenedioxythiophene) from sequential electropolymerization

“…This technique allowed us to follow the variation of the electronic conductivity of the thin films of conjugated polymers as a function of the applied potential. The setup consists of an array of six parallel microelectrodes on which the electroactive film is deposited [24]. The two outmost electrodes (2 and 6) are connected together to the potentiostat for the voltammetry (working electrode).…”