(266a) Dynamic Covalent Networks As Polymer Electrolyte Adhesives

Managing interfacial contact and charge transfer are inherent challenges when using solid electrolytes for all-solid-state electrochemical systems. The inclusion of soft polymeric materials as interfacial layers has been shown as a promising strategy in improving interfacial contact. Therefore, going forward, the design and development of polymeric materials with the ability to control adhesion and promote efficient ion transport at solid interfaces will play a major role in mitigating poor interfacial contact. Here, crosslinked polymer electrolytes containing structurally dynamic disulfide bonds have been synthesized to investigate their combined ion transport and adhesive properties. Dynamic network polymers of varying cross-link densities are synthesized via thiol oxidation. At optimal loading of lithium bis(trifluoromethane-sulfonyl-imide) (LiTFSI) salt, the ionic conductivities at 90 ° C are about 10^−4 and 10^−5 S/cm at the lowest and highest cross-linking, respectively. Notably, in comparison to the equivalent nondynamic network, the dynamic network shows a positive deviation in σ above 90 °C, which suggests the enhancement of ion transport occurs from the difference in structural relaxation on account of the dissociation of disulfide bonds. Lap shear adhesion and conductivity tests on ITO-coated glass substrates reveal the dynamic network exhibits a higher adhesive shear strength of 0.2 MPa (vs 0.03 MPa for the nondynamic network) and higher ionic conductivity after the application of external stimulus (UV light or heat). The adhesive strength and σ are stable over multiple debonding/rebonding cycles and, thus, demonstrating the utility of these structurally dynamic networks as solid polymer electrolyte adhesives.