Due to the increasing modern dependence on electronic devices, the production of carbon materials for supercapacitive and battery-based applications is an area of current research and innovation. It has been known for a considerable time that carbons can be formed through the electrolytic reduction of molten carbonate salts [1], however, little research has been put into in-depth understanding of the electrochemical characteristics of these materials. Electrochemical impedance spectroscopy can tell us a lot about the suitability of these materials for supercapacitive applications. This research investigates how the characteristics of carbons derived through molten carbonate reduction change based on synthesis conditions, with a particular focus being placed on the inductive and capacitive behaviour of the materials and on how inductances arise (Figure 1 (i)). This is done through the application of equivalent circuit modelling (Figure 1 (ii)) to cells constructed from synthesised and activated carbons, and the subsequent mathematical modelling of the system using complex non-linear least squared error curve fitting (CNLS) based on the interior-point algorithm in the MATLAB program. The frequency-dependant capacitance of the materials (Figure 1 (iii)) is reported and used as a point of comparison. Optimal carbon synthesis conditions of 500°C or low deposition current densities of 0.15 A/cm² have been found to both reduce inductive behaviour, and to produce carbons with capacitances as high as 160 F/g, close to 90% of that of the examined activated carbon.

[1] Hughes, M.A., J.A. Allen, and S.W. Donne, Carbonate Reduction and the Properties and Applications of Carbon Formed Through Electrochemical Deposition in Molten Carbonates: A Review. Electrochimica Acta, 2015. 176: p. 1511-1521.