Carbon Monoliths with Hierarchical Porous Structure for All-Vanadium Redox Flow Batteries

Batteries

Blagoj Karakashov¹  Vanessa Fierro¹  Alain Celzard¹  Anthony Dufour²  Jose Francisco Vivo-Vilches³  Ranine El Hage³  Mathieu Etienne³  Nicolas Brosse⁴ 

[1] Institute Jean Lamour (IJL), Université de Lorraine, Centre National de la Recherche Scientifique (CNRS), F-88000 Épinal, France;Laboratoire Réactions et Génie des Procédés (LRGP), Université de Lorraine, Centre National de la Recherche Scientifique (CNRS), F-54000 Nancy, France;Laboratoire de Chimie Physique et Microbiologie pour les Matériaux et l’Environnement (LCPME), Université de Lorraine, Centre National de la Recherche Scientifique (CNRS), F-54000 Nancy, France;Laboratoire d’Etudes et de Recherche sur le Matériau Bois (LERMAB), Université de Lorraine, F-54000 Nancy, France;

关键词: vanadium redox flow battery;    hierarchical carbon;    carbon electrode;    porosity;    sucrose-based carbon monolith;   

DOI  :  10.3390/batteries7030055

来源: DOAJ

【 摘 要 】

Carbon monoliths were tested as electrodes for vanadium redox batteries. The materials were synthesised by a hard-templating route, employing sucrose as carbon precursor and sodium chloride crystals as the hard template. For the preparation process, both sucrose and sodium chloride were ball-milled together and molten into a paste which was hot-pressed to achieve polycondensation of sucrose into a hard monolith. The resultant material was pyrolysed in nitrogen at 750 °C, and then washed to remove the salt by dissolving it in water. Once the porosity was opened, a second pyrolysis step at 900 °C was performed for the complete conversion of the materials into carbon. The products were next characterised in terms of textural properties and composition. Changes in porosity, obtained by varying the proportions of sucrose to sodium chloride in the initial mixture, were correlated with the electrochemical performances of the samples, and a good agreement between capacitive response and microporosity was indeed observed highlighted by an increase in the cyclic voltammetry curve area when the S_BET increased. In contrast, the reversibility of vanadium redox reactions measured as a function of the difference between reduction and oxidation potentials was correlated with the accessibility of the active vanadium species to the carbon surface, i.e., was correlated with the macroporosity. The latter was a critical parameter for understanding the differences of energy and voltage efficiencies among the materials, those with larger macropore volumes having the higher efficiencies.

【 授权许可】

Unknown