Design of Polymeric Scaffolds for Nonaqueous Ionogel Electrolytes
Department of Chemical and Biomedical Engineering, Tufts University
Ionogel electrolytes are a fascinating class of nonvolatile and nonflammable ion conductors featuring room temperature ionic liquids/molten salts that can enable safer electrochemical energy storage devices, wearable sensors, and many other applications. In first part of this presentation, I will describe the synthesis and characterization of a variety of novel (co)polymer-supported ionogels that can be readily formed, for example, via in situ photopolymerization within ionic liquid-based electrolytes, some of which are also facile lithium ion conductors. Varying the chemical nature of the functional groups within the scaffold facilitates the creation of polymer-supported ionogels that exhibit room temperature ionic conductivities as high as 12 mS/cm and compressive elastic modulus values that can be tuned over several orders of magnitude, from ~1 kPa to >10 MPa. Experimental evidence of increased ion pair dissociation, as well as the formation of physical cross-links that enhance gel stiffness due to the presence of zwitterionic groups, has been obtained; in some cases, gel self-healing behavior can also be observed. The second part of this talk will present our recent advances in the design of deep eutectic solvent (DES)-based gel electrolytes. Envisioned to be lower cost, more eco-friendly alternatives to traditional ionic liquids, DESs can be supported using a variety of polymeric scaffolds to create gel composites. Here, I will describe the successful incorporation of a well-studied DES (2:1 molar ratio mixture of ethylene glycol:choline chloride) into gel electrolytes using two distinct approaches. First, a covalently cross-linked scaffold is formed in situ via copolymerization of 2-hydroxyethyl methacrylate and poly(ethylene glycol) diacrylate inside the DES. In a second strategy, gelatin has been employed as a biopolymer scaffold to successfully realize highly stretchable, ionically conductive, and non-volatile DES gel electrolytes. In contrast to the covalent cross-linking approach, the biopolymer scaffold is assembled entirely
through non-covalent polymer interactions, which facilitates the formation of dynamic cross-links that enable a high degree of gel stretchability.
- 10:30 Refreshments
- 10:45–12:00 Talk