High Active Material Loading in Organic Electrodes Enabled by an in‐situ Electropolymerized π‐Conjugated Tetrakis (4‐Aminophenyl) Porphyrin

Abstract

AbstractPorphyrin complexes have been widely studied as promising electrode material in diverse energy storage systems and chemistries. However, like other organic electrodes, porphyrins often suffer from low conductivity and, consequently, require a significant amount (typically 40 %) of electrochemically inactive conductive carbon that occupies volume and mass without storing energy. In this study, we investigate [5,10,15,20 tetrakis(4‐aminophenyl)‐porphyrin] (TAPP) and its metal complexes as redox‐active cathode materials to address the aforementioned issues. The lithium‐ion cells prepared with a high content of CuTAPP active material (70 wt %) demonstrate a stable discharge capacity of ∼120 mAh/g when cycling with a constant current density of 1000 mA/g. The material also showed superior rate capability, e. g., ∼60 mAh/g at 8 A/g. The results of DFT calculations and experimental analysis indicate that the degree of planarity of the metalloporphyrins directly correlates to their cycling stability. Moreover, the contribution from the central metal redox during the cycling is found to be the reason for the significantly higher performance of the Cu‐complex compared to the metal‐free complex. The findings of this study show a general approach for facing common conductivity challenges of organic electrodes and open up a pathway for practical application of organics electrode materials in energy storage application.