Synthesis of organic cathode materials with pyrazine and catechol motifs for rechargeable lithium and zinc batteries

Although there are many reports on novel small organic cathode materials for rechargeable lithium and zinc batteries, there is still a lack of materials obtained with a facile synthesis from commercially available precursors, which also exhibit satisfactory cycling stability. Herein, we report a simple synthetic procedure for the simultaneous introduction of carbonyl and pyrazine units into small organic cathode materials. Materials were prepared through a condensation reaction between aromatic diamines and the sodium salt of rhodizonic acid. Building on an already known oxidized diquinoxalinecatechol (ODQC) material with cycling stability issues stemming from the dissolution in the electrolyte, we designed an expanded conjugated structure tetraquinoxalinecatechol (TQC). The ODQC shows fast capacity fading in Li-organic batteries having capacity retention of 16.8 % after 300 cycles at a current density of 50 mAg-1. The synthesis of the bigger TQC analog with lower solubility improves cycling stability with a high capacity retention of 82 % after 300 cycles at a current density of 50 mAg-1 and a maximum specific capacity of 223 mAhg-1 at an average voltage of 2.42 V vs. Li/Li+. In Zn-organic battery employing an aqueous electrolyte, TQC delivers a high maximum specific capacity of 301 mAhg-1 at 50 mAg-1 with an average voltage of 0.76 V, and 71 % capacity retention after 100 cycles.