Free-radical polymerizations of and in deep eutectic solvents: Green synthesis of functional materials

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adfm.202011176

Multifunctional Ionic Skin with Sensing, UV-Filtering, Water-Retaining, and Anti-Freezing Capabilities

Ionoskins: Nonvolatile, Highly Transparent, Ultrastretchable Ionic Sensory Platforms for Wearable Electronics

Natural biopolymer-based conductive hydrogels, which combine inherent renewable, nontoxic features, biocompatibility and biodegradability of biopolymers, and excellent flexibility and conductivity ...

Recent Progress in Natural Biopolymers Conductive Hydrogels for Flexible Wearable Sensors and Energy Devices: Materials, Structures, and Performance

There is a growing demand for devices that exhibit human skin-like sensory capabilities due to their broad applications in soft robotics and healthcare. Ionically conductive hydrogels have long been studied for wearable, flexible sensor applications; however, the volatility of water inevitably leads to dehydration issues that can limit the long-term use of hydrogel-based devices. In this report, highly stretchable, gelatin biopolymer-supported deep eutectic solvent (DES) gel electrolytes are presented as a promising nonvolatile alternative to hydrogels for ionic skin applications. The DES gel containing 22 wt% gelatin exhibited high stretchability (fracture strain > 300%) and a room temperature ionic conductivity of 2.5 mS cm−1. Capacitive-type pressure and strain sensors fabricated using gelatin-supported DES gel electrolytes provided linear responses over a wide range; an applied pressure as low as 1 kPa could be detected using a 1 V bias. A 3 × 3 sensor array was also constructed, which exhibited excellent performance for identifying the (multi)touch location(s) of applied pressure. These characteristics not only demonstrate the suitability of gelatin-supported DES gels for ionic skin applications, but also present a new class of materials for developing future nonvolatile sensors.

Highly stretchable and nonvolatile gelatin-supported deep eutectic solvent gel electrolyte-based ionic skins for strain and pressure sensing

Nonvolatile, ion-dense electrolytes, such as ionic liquids and deep eutectic solvents (DESs) are attractive candidates for safe, high-performance electrochemical/electrostatic energy storage devices. In this report, an inexpensive and eco-friendly DES (1 : 2 mixture of choline chloride/ethylene glycol) has been incorporated into a solid-state gel electrolyte using a chemically cross-linked polymer scaffold formed through in situ UV copolymerization of 2-hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) diacrylate. A high room-temperature ionic conductivity of 5.7 mS cm−1 has been obtained for a DES gel containing 13.2 vol % polymer scaffold. Tunable DES gel compressive elastic modulus values, between 14 kPa and 1.0 MPa, could be obtained by varying the polymer content. Clear evidence of hydrogen-bonding interactions between the poly(HEMA) scaffold and the DES anion was revealed through species self-diffusivity measurements as well as by FTIR spectroscopy. Using a 22.9 vol % polymer-supported DES gel as electrolyte/separator in a supercapacitor prototype with activated carbon fabric electrodes, a specific capacitance of 33.3 F g−1 and an energy density of 15.8 Wh kg−1 (based on the mass of two electrodes) were obtained during discharge at a current density of 0.01 A g−1. This work supports the notion that chemically cross-linked polymer-supported DES gel electrolytes are suitable for solid-state, flexible supercapacitor applications.

Chemically Cross‐Linked Poly(2‐hydroxyethyl methacrylate)‐Supported Deep Eutectic Solvent Gel Electrolytes for Eco‐Friendly Supercapacitors

A series of zwitterionic (ZI) copolymers, including both binary, fully-ZI and ternary, partially-ZI copolymer variations, have been successfully employed as scaffolds to support mechanically robust...

Zwitterionic Copolymer-Supported Ionogel Electrolytes Featuring a Sodium Salt/Ionic Liquid Solution

Turning on solid-state phosphorescence of platinum acetylides with aromatic stacking.

Ionic liquid gels have properties that offer several advantages for designing the future of wearable electrochemical energy storage devices. These include wide electrochemical stability windows, increased safety due to their ultralow volatility and reduced flammability, as well as a leak-proof nature. This chapter outlines the current state of ionic liquid gel electrolytes for two types of energy storage devices (i.e. batteries and supercapacitors) that can power wearable electronics. First, an overview of ionic liquid gels with formulations conducive to wearable applications is presented. Considerations that affect gel electrochemical performance are discussed for the purpose of future materials development. Next, properties relevant to improving ionic liquid gel electrolytes for lithium-based batteries and supercapacitors are suggested. Lastly, ionic liquid gel electrolyte integration with respect to flexible energy storage device fabrication is addressed. The scaling of current ionic liquid gel-based energy storage devices into body-worn applications is also discussed with the hope of influencing the future design of wearable technology that incorporates these materials.

Huan Qin

Papers

Highly stretchable and nonvolatile gelatin-supported deep eutectic solvent gel electrolyte-based ionic skins for strain and pressure sensing

Chemically Cross‐Linked Poly(2‐hydroxyethyl methacrylate)‐Supported Deep Eutectic Solvent Gel Electrolytes for Eco‐Friendly Supercapacitors

Zwitterionic Copolymer-Supported Ionogel Electrolytes Featuring a Sodium Salt/Ionic Liquid Solution

Turning on solid-state phosphorescence of platinum acetylides with aromatic stacking.

CHAPTER 14:Wearable Energy Storage Based on Ionic Liquid Gels