摘要
应用气相色谱方法初步探讨了聚合物锂离子电池在首次充电过程中于不同化成电压下产生气体的原因和机理.结果表明,当电池电解液采用1mol/LLiPF6-EC～DMC～EMC(三者体积比1∶1∶1)时,于化成电压小于2.5V下,产生的气体主要为H2和CO2等;化成电压为2.5V时,电解液中的EC开始分解,电压在3.0～3.5V的范围内,由于EC的还原分解,产生的气体主要为C2H4;而当电压大于3.0V时,由于电解液中DMC和EMC的分解,除了产生C2H4气体外,CH4,C2H6等烷烃类气体也开始出现;电压高于3.8V后,DMC和EMC的还原分解成为主反应.此外,当化成电压处于3.0～3.5V之间,化成过程中产生的气体量最大;电压大于3.5V后,由于电池负极表面的SEI层已基本形成,因此,电解液溶剂的还原分解反应受抑制,产生的气体的数量也随之迅速下降.
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 LiPF6_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 H2 and CO2, and when the charging voltage is 2.5 V, EC begins to decompose. Due to the decomposition of EC, the main generated gas is C2H4 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 C2H4 as well as CH4 and C2H6.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.
出处
《电化学》
CAS
CSCD
2003年第4期387-392,共6页
Journal of Electrochemistry
基金
国家重点基础研究发展规划 (2 0 0 2CB2 1 1 80 4)
科技部中小企业技术创新基金 (2 0 0 1 3 51 60 1 1 1 86)资助
