Effect of Electrolyte Composition on Biphasic Structural Electrolytes for Laminated Structural Batteries

Abstract

Bicontinuous solid-liquid electrolytes can combine high ionic conduction with high mechanical performance and provide an opportunity to realize laminated structural batteries. Polymerization-induced phase separation is a facile one pot reaction to make these electrolytes. It is a versatile method but requires control over the complex interaction of various parameters to tune the morphologies and properties of biphasic electrolytes as it is highly system dependent. This study examines the effects of thiol-ene chemistry and parameters such as porogen type and content, thiol content, and salt concentration in the liquid electrolyte, linking these factors to their curing behavior, morphology, and multifunctional properties. We present a toolbox showing how different morphologies and properties can be reached by changing these parameters. The porogen type and a 10% increase in the porogen content affected ionic conductivity by an order of magnitude. Thiol-ene chemistry accelerates the curing process but reduces mechanical properties while slightly increasing the ionic conductivities for small amounts of thiol. The best negative structural electrode, containing carbon fibers as negative electrode, showed increased rate capability compared to previous work and a discharge capacity of 219 mA h g-1 at a current density of 18 mA g-1 (∼0.08C). The results also indicate the potential of applying the concept of highly concentrated electrolytes in structural electrodes to improve safety and capacity retention while maintaining high specific capacities and good rate capability. Interestingly, the increased ionic conductivity of the electrolyte does not always imply an improved electrochemical performance of the structural electrode.