High Dielectric Poly(vinylidene fluoride)‐Based Polymer Enables Uniform Lithium‐Ion Transport in Solid‐State Ionogel Electrolytes
Jun‐Feng Liu, Zhanyu Wu, Florian J. Stadler, Yanfei Huang
Abstract
Abstract Ionic liquids (ILs)‐incorporated solid‐state polymer electrolytes (iono‐SPEs) have high ionic conductivities but show non‐uniform Li + transport in different phases. This work greatly promotes Li + transport in polymer phases by employing a poly (vinylidene fluoride‐trifluoroethylene‐chlorotrifluoroethylene) [P(VDF‐TrFE‐CTFE), PTC] as the framework of ILs to prepare iono‐SPEs. Unlike PVDF, PTC with suitable polarity shows weaker adsorption energy on IL cations, reducing their possibility of occupying Li + ‐hopping sites. The significantly higher dielectric constant of PTC than PVDF facilitates the dissociation of Li‐anions clusters. These two factors motivate Li + transport along PTC chains, narrowing the difference in Li + transport among varied phases. The LiFePO 4 /PTC iono‐SPE/Li cells cycle steadily with capacity retention of 91.5 % after 1000 cycles at 1 C and 25 °C. This work paves a new way to induce uniform Li + flux in iono‐SPEs through polarity and dielectric design of polymer matrix.