Ions Dynamics and Diffusion in Self-Healing Chemical Gel Electrolytes for Li-ion Batteries

This work deals with the mechanical and transport properties of a multifunctional gel electrolyte, based on a uniform, highly cross-linked network, capable of trapping a large amount of liquid electrolyte, yet preserving its solid character. Moreover, this gel has the peculiarity of easily self-healing in the case of physical damage such as severe cracks or fractures. Mainly, the study focusses on the basic understanding of the structure and dynamics in such complex quasi-solid-state electrolytes by using Pulsed Field Gradient (PFG) NMR spectroscopy. 1 H, 7 Li and 19F self-diffusion coefficients as well as spin-lattice relaxation times gave a frame on the long- and short-range mobility of the entrapped solvent molecules, lithium cation and PF6 anion, respectively. Furthermore, an investigation based on Dynamic Mechanical Analysis (DMA) provided information on the viscoelastic properties of gels and in particular measured the dynamic moduli and hydrodynamic radii. The experimental results from the two different approaches were helpfully complemented to better evaluate the network microstructure and the Lithium coordination within the gel.