关键词: 聚合物锂离子电池, 化成, 气体析出, SEI

Abstract: The gases of polymer lithium_ion battery(PLI) generated under different voltages during the first charging process were examined by means of gas chromatography (GC), and the mechanism of the gas generation was discussed. The electrolyte used in batteries was 1 mol/L LiPF6_EC～DMC～EMC=1∶1∶1(in volume). The results showed that when the charging voltage is less than 2.5 V, the main component of generated gases are H2 and CO2, and when the charging voltage is 2.5 V, EC begins to decompose. Due to the decomposition of EC, the main generated gas is C2H4 when the charge voltages between 3.0 V and 3.5 V. As the voltage is higher than 3.0 V, the generated gases composed of C2H4 as well as CH4 and C2H6.The later are caused by the decomposition of DMC and EMC. When the charging voltage is higher than 3.8V, the decomposition of DMC and EMC becomes dominant. Furthermore, when the voltages are between 3.0 V and 3.5 V, the volumes of generated gases are the most. Since the solid electrolyte interface (SEI) on the surface of carbon electrode has been formed, while the charging voltage higher than 3.5 V, the decomposition of the electrolyte slowed down and then restrained, and the volume of the generated gases decreased quickly.