Multifunctional structural polymer electrolytes via interpenetrating truss structures

Multifunctional structures such as mechanical load-bearing batteries and supercapacitors require electrolytes that possess both mechanical robustness and high ionic conductivity. In this study, we use additive manufacturing to build three-dimensional interpenetrating structures as model systems for structural electrolytes. Maxwell truss structures with varying solid volume fractions were fabricated by printing thermoplastic molds using fused filament fabrication, injecting and curing epoxy resins, and then etching away the mold. These unit cells were then subject to uniaxial compression to characterize mechanical stiffness, and intercalated with liquid electrolyte with a form-fitting test cell to measure system ionic conductivity. Finite element simulations of the truss structures provide good agreement with the experimental data, and are then used to calculate shear properties that would be difficult to measure experimentally. The results show that the present truss systems provide superior multifunctional properties compared to prior structural polymer electrolyte systems, and suggest that segregated truss structures are a promising approach for creating multifunctional systems.