Shape Persistent, Highly Conductive Ionogels from Ionic Liquids Reinforced with Cellulose Nanocrystal Network

Abstract

Shape-persistent, conductive ionogels where both mechanical strength and ionic conductivity are enhanced are developed using multiphase materials composed of cellulose nanocrystals and hyperbranched polymeric ionic liquids (PILs) as a mechanically strong supporting network matrix for ionic liquids with an interrupted ion-conducting pathway. The integration of needlelike nanocrystals and PIL promotes the formation of multiple hydrogen bonding and electrostatic ionic interaction capacitance, resulting in the formation of interconnected networks capable of confining a high amount of ionic liquid (≈95 wt%) without losing its self-sustained shape. The resulting nanoporous and robust ionogels possess outstanding mechanical strength with a high compressive elastic modulus (≈5.6 MPa), comparable to that of tough, rubbery materials. Surprisingly, these rigid materials preserve the high ionic conductivity of original ionic liquids (≈7.8 mS cm −1 ), which are distributed within and supported by the nanocrystal network-like rigid frame. On the one hand, such stable materials possess superior ionic conductivities in comparison to traditional solid electrolytes; on the other hand, the high compression resistance and shapepersistence allow for easy handling in comparison to traditional fluidic electrolytes. The synergistic enhancement in ion transport and solid-like mechanical properties afforded by these ionogel materials make them intriguing candidates for sustainable electrodeless energy storage and harvesting matrices.

Mineral Hydrogel from Inorganic Salts: Biocompatible Synthesis, All‐in‐One Charge Storage, and Possible Implications in the Origin of Life

“…Based on the magnified image, the ionic conductivities of the as‐made “Gel‐1M” and “Gel‐1M” containing 0.5 m of Li + , Mg 2+ , Na + , Zn 2+ , or Ca 2+ were evaluated to be 0.1, 0.15, 0.17, 0.12, 0.14, and 0.13 S cm −1 , respectively (Figure 5b). Because of the native ions in the gel (e.g., Cl − , Fe 3+ , NH 4+ ), the as‐made “Gel‐1M” already exhibited high ionic conductivity, which was further raised by the added metal salts to outperform most organic gel‐based electrolytes (e.g., 0.0078 S cm −1 for CNC/PIL ionogels [ 53 ] ). Besides, the semicircle in the high‐frequency region indicates this to be a gel with redox‐active centers; and the metal additives serve to enhance charge transfer, with the semicircles accordingly become smaller.…”

Supramolecular topology controlled self-healing conformal hydrogels for stable human–machine interfaces

“…S18, ESI †). The conductivity of the A 2.0 -HG 0.15 hydrogel is 0.658 S m À1 , which is better than most conductive hydrogels doped with ionic liquids, 29,38,39 carbon nanotubes, 40 and graphene. 41 An LED light became significantly darker with an increase in strain while, on the contrary, an LED light became significantly brighter under pressure (Fig.…”

Roles of Ionic Liquids in Adjusting Nature of Ionogels: A Mini Review

“…The gel showed 91% self-healing efficiency, which illustrated that the electrostatic interaction endowed the ionogel with good self-healing capability. Lee et al [8] synthesized an ionogel that cellulose nanocrystal (CNC) and a hyperbranched PIL with 32 sulfonate terminal groups combined the scaffold, [EMIM][TFSI] IL as a dispersed medium. When increasing the content of PIL from 0.3 to 1.2 wt%, the storage modulus of the ionogel significantly enhanced from below 25 to 250-550 Pa.…”

“…In this condition, the ionogel can inherit the most of properties of IL. [ 8 ] In some cases, ILs can also function as both polymer scaffold and dispersing medium. [ 7c ] The designability and unique properties of IL make ionogels tunable structure and function.…”