| Summary: | 碩士 === 國立臺北科技大學 === 資源工程研究所 === 104 === Redox Flow batteries are one of the most promising large-scale energy storage technologies, and the bromine electrode is often studied as the positive materials of the batteries. This study focuses on the charge-discharge characteristics of bromine electrodes. The effects of various conductive substrates and additives on Br-/Br2 reactions were analyzed with cyclic voltammetry, and the electrochemical mechanisms and the change of current densities about Br-/Br2 reactions were discussed. Experimental results show that the use of pyrolytic graphite substrate, with respect to the use of glassy carbon or Pt/C catalyst substrates, was electrochemically stable and obtained a higher current density for Br-/Br2. Moreover, the results of the progressive cyclic voltammogram show that the use of platinum substrate, with respect to the use of glassy carbon or pyrolytic graphite, had a wide potential window for Br-/Br2 reactions in acid solutions. However, when the bromine electrode was overcharged, the formed bromine would further oxidize to oxybromide and thus the coulombic efficiency of Br-/Br2 electrode decreased.. In-situ FTIR results show that the used additives combined with Br2(l) briefly and would release Br2(l) again. In addition, the result of diffusion experiments shows that by use of the additives less bromine penetrated across Nafion membrane, but more bromine penetrated across the composite membrane. The mechanism and behavior have been described in this study.
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