Insights into the Ionic Conduction Mechanism of Quasi‐Solid Polymer Electrolytes through Multispectral Characterization

Abstract

Quasi-solid polymer electrolytes (QPE) composed of Li salts, polymer matrix, and solvent, are beneficial for improving the security and energy density of batteries. However, the ionic conduction mechanism, existential form of solvent molecules, and interactions between different components of QPE remain unclear. Here we develop a multispectral characterization strategy combined with first-principles calculations to unravel aforesaid mysteries. The results indicate that the existential state of solvent in QPE is quite different from that in liquid electrolyte. The Li cations in gel polymer electrolyte are fully solvated by partial solvent molecules to form a local high concentration of Li + , while the other solvent molecules are fastened by polymer matrix in QPE. As a result, the solvation structure and conduction mechanism of Li + are similar to those in high-concentrated liquid electrolyte. This work provides a new insight into the ionic conduction mechanism of QPE and will promote its application for safe and high-energy batteries.

Decoupling of ion pairing and ion conduction in ultrahigh-concentration electrolytes enables wide-temperature solid-state batteries

“…The interaction between every component was evaluated via the change in bond length in the functional groups. 38 Specifically, the bond length of SQO (DMSO) was increased in Li + /DMSO but did not change in TFSI À /DMSO and PVDF-HFP/DMSO (Fig. 6a).…”

In‐situ Polymerized Gel Polymer Electrolytes with High Room‐Temperature Ionic Conductivity and Regulated Na+ Solvation Structure for Sodium Metal Batteries

“…For example, He et al revealed that the Li + ions in GPE are fully solvated by partial solvent molecules to form a locally high concentration of Li + owing to the existence of a polar polymer matrix, which is quite different from LE. [ 22 ] It should be noted that Na + , with weaker Lewis acidity and larger ion radius than Li + , displays lower interaction with conventional carbonate electrolyte molecular, [ 23 ] which may lead to a different Na + transport way from Li + . However, besides unsatisfactory ionic conductivity of GPEs, researches on Na + ion behavior in the polymer matrix and its distinction from that in the LE system in terms of its solvation structure, coordination environment, and their further influence on battery performance are largely inadequate.…”

A Single‐Ion Conducting Network as Rationally Coordinating Polymer Electrolyte for Solid‐State Li Metal Batteries

“…In PTF‐ x EO system without Li + ion, each sample exhibits similar bond length of C‐O‐C groups (1.414 Å); After coordinating Li + , the bond length in PTF‐4EO changes to 1.432 Å owing to the electrostatic potential interactions, which is larger than that of PTF‐5EO (1.429 Å) and implying a weaker EO‐Li + interaction. [ 16 ] The electrostatic potential calculation further verified the O‐Li + coordination in PTF‐4EO (Figure S6, Supporting Information). In addition, 7 Li solid state magic angle spinning nuclear magnetic resonance (ssMAS NMR) spectra was employed to study the Li + ‐related interactions of PTF‐4EO.…”