| Summary: | 碩士 === 國立聯合大學 === 能源工程學系碩士班 === 104 === During discharge of the metal-air battery, the oxygen reduction reaction (ORR) occurs on the air electrode. The air electrode uses porous carbon material. Electrode material, composition, and its manufacturing conditions will influent the electrode performance. In this study, the electrode paste uses XC-72R carbon powder as the substrate. The paste uses ethylene glycol as the solvent. It dopes with a small amount of polytetrafluoroethylene (PTFE) as a water expelling agent for the electrode. Paste is grinding with three-wheel roller or with an agate mortar. The mortar grinded paste looks preferably dispersed. The rheological properties of paste obtained by different grinding conditions are analyzed. With fixed paste composition, both viscosity and shear stress of the paste grinded by mortar are higher than that grinded by three-wheel roller. Mortar is chose as the grinding method of paste. By varying the composition of ethylene glycol and PTFE, layer of coating, a doctor blade method is used to coat the paste evenly on a 24BC carbon paper. After 350℃, 12.5 kg cm-2 hot press, the ORR electrode is made. The electrode is placed in a jacketed reactor. Single cell has three-electrodes configuration. Electrode characteristics are analyzed with linear scanning voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). In single layer of coating, the optimum ratio of the paste (C:EG:PTFE) is 1:4:0.05. The electrode potential at -0.6 V (vs AgCl), the current density reaches 125 mA cm-2. As comparison, catalyst containing Pt, at -0.6 V (vs AgCl), 10% Pt/C and 5% Pt/C have current density of 160 and 133 mA cm-2 respectively.
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