In the search for novel polymeric molecules that could be used as electroactive materials, seven novel polyenaminones were prepared in high yields by the transaminative polymerization of resorcinol-derived bis-enaminones with m- and p-phenylenediamine and with 2,5-diaminohydroquinone. The obtained polymers show very low solubility in organic solvents and absorb UV light and visible light at wavelengths below 500 nm. All the obtained polymeric products were tested for redox activity in a Li battery setup. The 2,5-diaminohydroquinone-derived compound showed the best redox activity, with a maximum capacity of 86 mAh/g and relatively good capacity retention, thus confirming the hydroquinone group as the primary redox-active group. Other potential redox-active groups, such as resorcinol and conjugated carbonyls, showed limited activity, while variations in the phenylene groups and the substitution of phenolic groups in the resorcinol residue did not impact the electrochemical activity of the polymers. Their electrochemical properties, together with their previously established chemical recyclability, make polyenaminones promising scaffolds for the development of materials for sustainable energy storage applications.

Despite the rapid expansion of the organic cathode materials field, there is still a lack of materials obtained through facile synthesis that have stable cycling and high energy density. Herein, we report a two-step synthesis of small organic molecule from commercially available precursors that can be used as a cathode material. Oxidized tetraquinoxalinecatechol (OTQC) was derived from tetraquinoxalinecatechol (TQC) by the introduction of additional quinone redox active centers into the structure. The modification increased the voltage and capacity of the material. The OTQC delivers a high specific capacity of 327 mAhg-1 with an average voltage of 2.63 V vs. Li/Li+ in the Li-ion battery. That corresponds to an energy density of 860 Whkg-1 on the material level. Furthermore, the material demonstrated excellent cycling stability, having a capacity retention of 82 % after 400 cycles. Similarly, the OTQC demonstrates increased average voltage and specific capacity in comparison with TQC in Zn-organic battery using aqueous electrolyte, reaching the specific capacity of 326 mAhg-1 with an average voltage of 0.86 V vs. Zn/Zn2+. Apart from good electrochemical performance, this work provides an additional in-depth analysis of the redox mechanism and degradation mechanism related to capacity fading.

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.

Aqueous zinc-ion batteries are one of the most promising candidates for large-scale energy storage applications.

Degradation of carbon-supported Pt nanocatalysts in fuel cells and electrolyzers hinders widespread commercialization of these green technologies. Transition between oxidized and reduced states of Pt during fast potential spikes triggers significant Pt dissolution. Therefore, designing Pt-based catalysts able to withstand such conditions is of critical importance. We report here on a strategy to suppress Pt dissolution by using an organic matrix tris(aza)pentacene (TAP) as an alternative support material for Pt. The major benefit of TAP is its potential-dependent conductivity in aqueous media, which was directly evidenced by electrochemical impedance spectroscopy. At potentials below ∼0.45 VRHE, TAP is protonated and its conductivity is improved, which enables supported Pt to run hydrogen reactions. At potentials corresponding to Pt oxidation/reduction (>∼0.45 VRHE), TAP is deprotonated and its conductivity is restricted. Tunable conductivity of TAP enhanced the durability of the Pt/TAP with respect to Pt/C when these two materials were subjected to the same degradation protocol (0.1 M HClO4 electrolyte, 3000 voltammetric scans, 1 V/s, 0.05-1.4 VRHE). The exceptional stability of Pt/TAP composite on a nanoscale level was confirmed by identical location TEM imaging before and after the used degradation protocol. Suppression of transient Pt dissolution from Pt/TAP with respect to the Pt/C benchmark was directly measured in a setup consisting of an electrochemical flow cell connected to inductively coupled plasma-mass spectrometry.