Boric acid thermal etching graphite felt as a high-performance electrode for iron-chromium redox flow battery

Abstract

Iron-chromium redox flow battery（ICRFB） is a secondary battery capable of deep charge and discharge. It is a novel electrochemistric equipment for energy storage. ICRFB has around wide concern as it possesses advanced characteristics such as high energy, long cycle life, and environmental friendly. Graphite felt is a common electrode material for ICRFB because of its high temperature resistance, corrosion resistance, infinite specific surface area, and admirable electroconductibility. However, poor hydrophilicity and electrochemical activity lead to the graphite felt to be modified to be better applied in ICRFB. To improve the electrochemical activity of graphite felt, the PAN-based graphite felt was activated by boric acid thermal etching, and tested with SEM analysis, electrochemical analysis, and charge-discharge test. The results showed that the electrochemical activity and reversibility of boric acid thermal etching graphite felt impregnated with 25% boric acid solution were significantly improved after thermal treatment at 500℃ for 5 hours. The Energy Efficiency of boric acid thermal etching graphite felt impregnated with 25% boric acid solution in ICRFB could reach more than 85%, which was about 9.5% higher than that of ICRFB with untreated graphite felt (1#) as electrode.

Recent Advances for Electrode Modifications in Flow Batteries: Properties, Mechanisms, and Outlooks

“…X. M. Wang et al. used the boric acid thermal etching method to improve the electrochemical activation of GF [56] . The results showed that the electrochemical activity and reversibility of boric acid thermally etched GF was significantly improved after heat treatment with 25% boric acid solution for 5 h. The wettability and electrochemical activity of the GF were significantly improved mainly due to two reasons.…”

Progress of organic, inorganic redox flow battery and mechanism of electrode reaction

“…Acid and heat treatment is considered the most "convenient and effective" modification method. Chen et al researched the electrochemical performance of SiO 2 -modified GF and its application in ICRFBs [84]. They impregnated GF with silicic acid and then loaded SiO 2 on the surface of GF by heat treatment (Fig.…”

Machine learning-enabled performance prediction and optimization for iron–chromium redox flow batteries

“…18 Additionally, studies by Li et al have focused on improving the electrocatalytic performance of graphite felt electrodes through treatments such as boric acid thermal etching to enhance hydrophilicity. 19 After H 3 BO 3 thermal etching, the hydrophilicity of the graphite felt was obviously enhanced.…”