La and Sr Composite Oxides-modified Graphite Felt for Aqueous Organic Redox Flow Batteries

In this study, aqueous organic redox flow batteries(AORFBs) with NaCl as supporting electrolyte were investigated. In AORFBs, the chlorine evolution reaction should be retarded, not the hydrogen evolution reaction. To enhance the catalytic activity of the graphite felt(GF) electrode, the metal oxides were proposed to decorate on the GF surface. Among the loading oxides, significant enhancement of the mass transfer and reaction activity was obtained by the presence of LaSrO_x nanoparticles. X-Ray photoelectron spectroscopy and contact angle measurements revealed that the content of oxygen-containing groups and the hydrophilicity were remarkably increased. After the electrode assembled in the battery, the LaSrO_x/GF electrode presented huge enhancement of the battery performance, obviously increasing in the battery capacity and efficiency. At a current of 50 Am/cm², the energy efficiency(EE) of the battery increased from 54.76% to 61.37% by the LaSrO_x/GF electrode. Furthermore, the cyclability of the system tested that no obviously fading was observed after 100 cycles, signifying the excellent stability of the LaSrO_x/GF electrode.