Investigation on the determining factor in the performance of in situ fabricated lithium polymer secondary battery

In our preliminary research, an in situ fabrication of the lithium polymer cell starting from Li/1 M LiTFSI in DOL + DME (2:1 by weight)/LiCoO2 cell is successfully achieved owing to the electro-polymerization of DOL solvent. Basing on previous work, a comprehensive investigation on the new technology is conducted and some significant result is presented in this paper. The influence of three leading factors such as: current rate, upper limit voltage and temperature are laid a heavy emphasis. It is found that upper limit voltage is a prerequisite to the initiation of DOL polymerization as long as the operating temperature is kept far below the temperature limit for the occurrence of thermal-initiated polymerization. Once this requirement is satisfied, the current rate exerts a positive influence on DOL's electro-polymerization and helps to the formation of a conductive polymer electrolyte, but as another two factors are concerned, the case is just the reverse. And besides, benefiting from the “regulation” effect of current rate, the lack of capacity retentivity that is encountered during the high-temperature or high-voltage cycling can be compensated by an electrochemical pretreatment. And finally, it is indicated that all the influential mechanism tightly related to the variation in the cell internal resistance.