Agradecimentos: The authors are very grateful to LNNano/CNPEM for SEM and XPS support and to the financial support from the Brazilian funding agencies CNPq (301486/2016–6), FAPESP (2014/02163–7, 2017/11958–1, 2018/20756–6). L.M. Da Silva wishes to thank FAPEMIG (Financial support for the LMMA/UFVJM Laboratory) and CNPq (PQ-2 grant: Process 301095/2018–3). The authors gratefully acknowledge the support from Shell and the strategic importance of the support given by ANP (Brazil's National Oil, Natural Gas and Biofuels Agency) through the R&D levy regulation Ver menos

We report in this work the surface chemistry and the electrochemical studies on electrodes composed of randomly oriented multi-walled carbon nanotubes supported on stainless-steel (AISI:ROMWCNTs) confined in symmetric coin cells, before and after the electrode aging process accomplished in aqueous and organic electrolytes. We contrasted features from the as-grown and aged electrodes obtained during the different electrochemical experiments using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy techniques. Also, several studies involving the Raman, Fourier transform infrared, and X-ray photoelectron spectroscopy, and the scanning electron microscopy techniques were carried out. Our experimental findings indicated that the electrode material shows fair good stability during the charge-discharge processes carried out using the different electrolytes. The aging process observed for each electrolyte revealed the formation of reaction by-products during the long-term charge-storage endurance tests. We additionally performed the in situ (operando) Raman characterization study of the electrodes under dynamic polarization conditions. In this sense, we verified the reversible Raman shifts (e.g., G & D bands) accounting for the dynamic nature of the charge accumulation-depletion processes occurring inside the electrical double-layer structure Ver menos