A physical organogel electrolyte: characterized by in situ thermo-irreversible gelation and single-ion-predominent conduction

Abstract

Electrolytes are characterized by their ionic conductivity (σ_i). It is desirable that overall σ_i results from the dominant contribution of the ions of interest (e.g. Li⁺ in lithium ion batteries or LIB). However, high values of cationic transference number (t₊) achieved by solid or gel electrolytes have resulted in low σ_i leading to inferior cell performances. Here we present an organogel polymer electrolyte characterized by a high liquid-electrolyte-level σ_i (~10¹ mS cm⁻¹) with high t₊ of Li⁺ (>0.8) for LIB. A conventional liquid electrolyte in presence of a cyano resin was physically and irreversibly gelated at 60°C without any initiators and crosslinkers, showing the behavior of lower critical solution temperature. During gelation, σ_i of the electrolyte followed a typical Arrhenius-type temperature dependency, even if its viscosity increased dramatically with temperature. Based on the Li⁺-driven ion conduction, LIB using the organogel electrolyte delivered significantly enhanced cyclability and thermal stability.