Redox Solid Energy Boosters for Flow Batteries: Polyaniline as a Case Study. (1st May 2017)

• Record Type: Journal Article
• Authors: Zanzola, Elena; Dennison, C.R.; Battistel, Alberto; Peljo, Pekka; Vrubel, Heron; Amstutz, Véronique; Girault, Hubert H.
• Is Part Of: Electrochimica acta. Volume 235(2017)
• Page Start: 664
• Page End: 671
• Publication Date: 2017-05-01
• Subjects: redox flow battery -- redox targeting -- redox mediator -- solid charge storage materials -- polyaniline; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2017.03.084
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: In this work, the viability of polyaniline as a solid charge storage material in an aqueous redox-mediated flow battery is investigated. Fe(III/II) and V(IV/III) were identified as potential redox mediators to target the emeraldine-pernigraniline and leucoemeraldine-emeraldine redox transitions of the polymer. An indirect chemical cycling method was developed and used to investigate the charging/discharging of the polymer by the selected redox mediators. With Fe(III/II) as a redox mediator, respectable specific capacity and cycling stability were demonstrated over 25 cycles. V(IV/III) was deemed unsuitable as a redox mediator, due to rather poor kinetics. When added to the electrolyte tanks of a complete flow battery, a conductive composite of polyaniline and carbon black provided a significant improvement in capacity, exhibiting a specific capacity of 64.8 mA h g −1 at a current density of 38.5 mA cm −2 . This represents a three-fold improvement in volumetric capacity, compared with the electrolyte alone. Moreover, the addition of the polyaniline composite was observed to lower the average potential at the positive electrode, providing a considerable improvement in voltage efficiency. This work demonstrates the potential of utilizing redox mediators to enable bulk solid-phase charge storage in the tanks of aqueous redox flow batteries.