Understanding the Influence of Cation and Anion Chemistries on the Ion Transport Properties of Polyzwitterionic Ionogels

Polyzwitterion (polyZI) supported ionogel electrolytes have been demonstrated to be a promising candidate for battery electrolyte applications. In this study, we used atomistic molecular dynamic simulations to probe the impact of cation and anion chemistries to understand their impact on the conductivities and transference numbers of the polyZI ionogels. Our model system is comprised of ZI poly (2- methacryloyloxyethyl phosphorylcholine) (pMPC) loaded with 0.5M X⁺– Y^-/N-butyl-N-methylpyrrolidinium Y^- (BMP–Y^-) ionic liquid electrolyte (where X⁺ = Li⁺ or Na⁺ and Y^- = BF₄^-, PF₆^-, TFS^- and TFSI^-). Our findings demonstrate that the alkali metal cation — zwitterionic polymer and alkali metal cation — common anion interactions are critical to the dynamic and structural properties in the polyzwitterionic ionogels. Additionally, we show that systems with alkali metal ions that are less coupled to the anions play a key role in achieving higher inverse Haven ratios, while systems with stronger alkali metal - polyZI interactions are crucial for enhancing alkali metal transference numbers. Lastly, we discuss guiding the polyZI ionogel designs based on our findings.