Screen printed bifunctional gas diffusion electrodes for aqueous metal-air batteries: Combining the best of the catalyst and binder world. (20th December 2017)

• Record Type: Journal Article
• Authors: Flegler, Andreas; Hartmann, Sarah; Settelein, Jochen; Mandel, Karl; Sextl, Gerhard
• Is Part Of: Electrochimica acta. Volume 258(2017)
• Page Start: 495
• Page End: 503
• Publication Date: 2017-12-20
• Subjects: Bifunctional gas diffusion electrode -- Bifunctional air-cathode -- Screen printing -- Hydrophilic and hydrophobic reactive layer; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2017.11.088
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: The oxygen reactions in a metal-air battery during discharge (oxygen reduction reaction: ORR) and charge (oxygen evolution reaction: OER) take place on accessible catalyst sites at the gas diffusion electrode (GDE or air-cathode). Typical low-cost catalysts only have function for either the ORR (e.g. MnO2 ) or the OER (e.g. NiCo2 O4 ). To overcome this issue, either a bifunctional catalyst or a bifunctional GDE is needed. Herein, we focus on the development of such a bifunctional GDE. One key is the use of a carefully tuned binder which allows optimal wetting of the GDE. The combination of carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) can replace conventional binders such as polytetrafluoroethylene (PTFE). Using this binder system, two different approaches to combine the two catalysts γ-MnO2 and NiCo2 O4 in one cathode are employed. The first is to mix the ORR catalyst γ-MnO2 and the OER catalyst NiCo2 O4 for integration in the same reactive layer. The second is to build a GDE with two reactive layers which are screen printed on top of each other. The reactive layer facing the air side consists of the ORR catalyst γ-MnO2 and the binders CMC/SBR. The second reactive layer, facing the electrolyte, consists of the hydrophilic binder CMC and the OER catalyst NiCo2 O4 . This double-layer design with two different catalyst species results in a better cycling behavior. Graphical abstract: