Electrochemical impedance spectroscopy (EIS) has been proposed as an in situ strategy for the analysis of materials properties applied in the study of lithium-ion batteries (LIBs). However, the number and physical nature of the processes occurring simultaneously, combined with the typical interpretation of EIS spectra make the study challenging. To make the EIS interpretation more inclusive, in this work a graphical Bode diagram deconvolution is proposed, utilizing time constants τ (R-CPE), associated with relaxation of the phenomena occurring in battery composite electrodes. Since the effect of the additives on the electrode composite is still controversial and difficult to analyze for other in situ techniques, the graphical strategy is first applied to a LiFePO 4 cathode with PVDF as the binder, to discriminate the contribution of each τ during different state of charge (SOC). This is done by removing the influence of counter electrode using a commercial three-electrode set-up cell. Then, the same cathode was evaluated, but with a Single Lithium-Ion Conducting Binder (SLICB). The electrode modification was easily observed with the graphical analysis. The results show that SLICB improved the speed of the processes, moving them to high frequencies, given that the polymer provides a continuous supply of ions diminishing concentration polarization.

Purpose – The purpose of this investigation is to study the corrosion inhibition of carbon steel (CS) using a “green” inhibitor, Opuntia ficus-indica, in an aerated, 0.5 M H2SO4 solution at different concentrations and temperatures. Design/methodology/approach – Weight loss determinations, surface studies, electrochemical impedance spectroscopy and potentiodynamic polarization were applied during the investigation. Findings – It was observed that Opuntia ficus-indica extract can decrease the corrosion rate of CS, and its efficiency increases with increasing concentration up to 1,000 ppm and with time, but decreases with increasing the temperature from 25 to 600C. The inhibitory activity is due to the presence of phenolic compounds in its chemical structure. Research limitations/implications – The work was done under static conditions, whereas in acid cleaning conditions, there is a dynamic system. However, the findings may apply to both the systems. Practical implications – CS is used in acidic environments in the acid cleaning industry. Social implications – Results of this work show that it is possible to reduce the cost of repair of equipment and the environmental impact of corrosion. Originality/value – There are very few investigations on the study of Opuntia ficus-indica leaf extract as a green inhibitor in an acidic environment.

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