Hydrophobic, Carbon Free Gas Diffusion Electrode for Alkaline Applications. Issue 14 (27th October 2020)

• Record Type: Journal Article
• Authors: Bekisch, Artur; Skadell, Karl; Poppitz, David; Schulz, Matthias; Weidl, Roland; Stelter, Michael
• Is Part Of: Journal of the Electrochemical Society. Volume 167:Issue 14(2020)
• Publication Date: 2020-10-27
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/abbdd4
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : In this work we present a carbon free gas diffusion electrode (GDE) design. It is a first step towards improvement of technologies like alkaline fuel cells, some alkaline electrolyzes and metal-air-batteries by circumventing carbon degradation. A nickel-mesh was made hydrophobic and subsequently electrochemically coated with MnOx as electrocatalyst. By this, a carbon free GDE was prepared. The contact angle, specific surface area (BET), pore size distribution, crystal phase (XRD) and electrochemical properties were determined. The deposition scan rate ( r scan ) during dynamic MnOx deposition altered the macro surface structure, pore size distribution and deposited mass. High catalyst masses with high specific surface area were achieved by lower r scan, but hydrophobicity was decreased. Impedance spectroscopy showed that higher MnOx mass will increase the ohmic resistance, because of the low conductivity of oxides, such as MnOx . The diffusion of dissolved oxygen is the major contributor to the total resistance. However, the polarization resistance was reduced by increased specific surface area of MnOx . It was concluded that the ORR and OER are limited by diffusion in this design but nevertheless showed reasonable activity for ±10 mA cm −2 corresponding to ∼8 Ω cm −2 while references exhibited ∼3.5 Ω cm −2 .