N-Substituted Carbazole Derivate Salts as Stable Organic Electrodes for Anion Insertion

Herein the design, synthesis and electrochemical characterization of a set of insoluble molecular carbazole derivatives for electrochemical energy storage is proposed. Two strategies, based on the incorporation of an insoluble fragment or dimerization, were carried out to avoid the dissolution of the active material in the organic carbonate-based liquid electrolyte solvent. The synthesized compounds enable the reversible anion intercalation from electrolyte, around 4.0 V vs. Li, through a p-type mechanism, and showed an improvement in cycling stability, making them suitable for application as metal-free positive electrodes for electrochemical energy storage systems. A first investigation to determine the impact of the electrolyte composition on the anion insertion mechanism and complemented with understanding of the redox mechanism was also carried out.