Effects of air electrode and separator on cycling performance of lithium air battery

• Main Authors: Jia Cheng Chang, 張家誠
• Other Authors: S. J. Lue
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/hysxc9

碩士 === 長庚大學 === 化工與材料工程學系 === 106 === Lithium oxygen battery change the cathode into a air-breathing structure, and use the oxygen as the reactor in the cathode. The operation leads that Lithium air battery provides higher theoretical voltage. Also the theoretical specific energy reaches up to 12 kWh/kg, which is close to the specific energy of the fossil oil, 13 kWh/kg. Among the components in the Lithium oxygen battery, the separator and structure of the cathode have tremendous effect on the efficiency of charging/discharging, impedance and max power rate. The cathode usually decides the charge/discharge efficiency of the whole battery, while separator affects the impedance. On the cathode side, this research will focus on how adding microporous layer and Pt catalyst onto the cathode will effect the cycle life, impedance and max power rate. After adding the microporous layer and Pt catalyst, the max power rate rise from 2.91 mW/cm2 to 4.52 mW/cm2, the ohm impedance reduced due the good conductivity of the Pt particles, while the electrical chemical impedance raised a little bit. The cycle life extended from 40 hours to 250 hours, also the over potential on the first cycle reduce from 1.4V to 1.0V. In order to improve the moisture prevention of the battery, this research changed the test model from the bottle cell to the MTI model. MTI model has 1/16 stainless steel gas tube and is also made of stainless steel, these advantages can stop the moisture from going into the battery’s materials. Under the circumstances that cathode has microporous layer and Pt catalyst on different side of it, the cycle life extended from 250 hours to 1240 hours. On the separator side, the research hopes improve the over potential, cycle life, impedance, open circuit voltage and max power rate via changing the separators into glass fibers or Celgrad polymer commercial separators. The result showed that after changing the separator from glass fiber into Celgard separator, the ohm impedance decreased a little bit, while the electrical chemical impedance was large at first but still decreased as time goes by. The cycle life increase from 1240 hours to 1330 hours due to the smaller pores on the Celgard membrane comparing to the glass fiber, which prevents moisture from penetrating to the lithium metal also allowing lithium ion flows. But the over potential and max power rate didn’t change a lot.