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. 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 LiTFSI salt, the ionic conductivity (σ) at 90 ° C is ca. 10⁻⁴ S/cm. 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 due to dissociation of disulfide bonds. Lap shear adhesion and conductivity tests on ITO 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 σ 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 materials as polymer electrolyte adhesives.