Enhancing the thermal stability of LiCoO_2 electrode by 4-isopropyl phenyl diphenyl phosphate in lithium ion batteries

摘要

To enhance the thermal stability of LiCoO_2 in lithium ion batteries, 4-isopropyl phenyl diphenyl phosphate (IPPP) was investigated as an additive in 1.0 M LiPF_6/EC + DEC (1:1 wt. percent) electrolyte. The thermodynamics and kinetics parameters of the single LiCoO_2 and Li_xCoO_2-IPPP-electrolyte are detected and calculated based on the C80 microcalorimeter data. The results indicated that IPPP can enhance the thermal stability of LiCoO_2 electrode in lithium ion battery more or less corresponding to the IPPP content in electrolyte. Furthermore, the electrochemical performances of LiCoO_2/IPPP-electrolyte/Li cells become slightly worse after using IPPP additive in the electrolyte. This alleviated trade-off between thermal stability and cell performance provides a possibility to formulate an electrolyte containing 5-10 percent of IPPP and enhance the LiCoO_2 electrode thermal stability with minimum sacrifice in performance.