Biosourced and biodegradable organic electrode materials respond to the need for sustainable storage of renewable energy. Here, we report on electrochemical capacitors based on electrodes made up of quinones, such as Sepia melanin and catechin/tannic acid (Ctn/TA), solution-deposited on carbon paper engineered to create high-performance interfaces. Sepia melanin and Ctn/TA on TCP electrodes exhibit a capacitance as high as 1355 mF cm−2 (452 F g−1) and 898 mF cm−2 (300 F g−1), respectively. Sepia melanin and Ctn/TA symmetric electrochemical capacitors operating in aqueous electrolytes exhibit up to 100% capacitance retention and 100% coulombic efficiency over 50,000 and 10,000 cycles at 150 mA cm−2 (10 A g−1), respectively. Maximum power densities as high as 1274 mW cm−2 (46 kW kg−1) and 727 mW cm−2 (26 kW kg−1) with maximum energy densities of 0.56 mWh cm−2 (20 Wh kg−1) and 0.65 mWh cm−2 (23 Wh kg−1) are obtained for Sepia melanin and Ctn/TA.
Résumé
Introduction A lʼère du développement massif de la télémédecine, lʼaccès à des photographies à distance est essentiel. Nous avons donc voulu montrer quʼil est possible de réaliser
des photographies de qualité avec des appareils simples à lʼère de lʼimagerie multimodale coûteuse. Nous illustrons que lʼutilisation du smartphone préalablement monté sur une lampe à fente
a permis de recueillir des photographies précises du segment antérieur, notamment dans notre article, avec un cas de dystrophie épithéliale de Cogan.
Matériel et méthodes Lʼinstallation de ce dispositif est détaillée et imagée. Nous avons monté un smartphone sur les oculaires de la lampe à fente (BQ 900 LED Haag-Streit) et pris
des images de la cornée dʼun patient atteint dʼune dystrophie de Cogan bilatérale.
Résultats Des images statiques de qualité des signes cliniques de cette dystrophie ont pu être prises de manière simple et reproductible. Nous avons corrélé ces signes cliniques avec
les caractéristiques OCT typiques de la pathologie.
Discussion La dystrophie de Cogan nʼétant pas une pathologie si fréquente, lʼintérêt ici est double : le recueil de belles photographies à lʼaide dʼun appareil simple et peu coûteux,
ainsi que lʼobservation et la sauvegarde de la sémiologie clinique particulière de cette dystrophie épithéliale. Des publications ont déjà traité de ce sujet, mais nous avons voulu insister
sur le montage de cet appareil sur une lampe à fente, qui permet une bonne observation de la sémiologie ophtalmologique. Notre présentation démontre quʼil est possible dʼobtenir des
photographies du segment antérieur de qualité avec un matériel simple pour une utilisation clinique quotidienne tant en cabinet quʼen milieu hospitalier.
The increasing demand for sustainable energy storage devices has driven the research on redox-active biosourced materials. Quinone-based tannins are present in the waste of the forest industry. Here we report a study on two molecules belonging to the tannin family, tannic acid (TA) and catechin (Ctn). An increase in the energy density of 835% for Ctn on activated carbon paper current collectors, in symmetrical configuration has been observed in aqueous electrolyte. Interestingly, in galvanostatic conditions, the surface of the carbon current collector undergoes changes that increase its capacity by two orders of magnitude. The resulting synergistic effect of the activation of the carbon surface and presence of redox active tannins is beneficial for the performance of the storage device. Work is in progress to improve the device cyclability (stability).
Growing environmental concerns have spurred investments in intermittent renewable energies and electric vehicles. The parallel boom in portable consumer electronics has placed considerable stress on electrochemical energy storage, creating environmental and availability issues for key inorganic materials. The need to switch to bio-sourced, widely available, organic materials is confronted by the low conductivity and stability of most candidates and the difficulties of creating an efficient, metal-free current collector. In this work, we present an acidic thermal oxidative treatment utilizing carbon paper as an efficient electrode for biosourced organic molecules. Following deposition of bio-sourced materials sepia melanin and catechin (a tannin) with high specific capacitance and energy density showed very promising results for supercapacitors. Up to 228 F/g capacitance, with 100% retention after 5 000 cycles, 100% coulombic efficiency, 69.71, 81.25 W h/kg and 22.20 and 12.66 kW/kg energy and power densities for sepia melanin and catechin, respectively, were achieved for symmetric supercapacitor devices.
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