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ABSTRACT Polyzwitterions (polyZIs), macromolecules with repeating ampholytic monomers, are a novel class of materials with attractive properties for battery electrolytes. In this study, we probe the ion transport characteristics and underlying mechanisms in two salt‐doped (Li⁺‐TFSI⁻) polyZIs of similar composition with contrasting zwitterion (ZI) ionic organization: pendant monomers organized via backbone‐anion‐cation (B‐ZI⁻‐ZI⁺, Motif B) and backbone‐cation‐anion (B‐ZI⁺‐ZI⁻, Motif C). Within both Motifs B and C, the counterion of the pendant‐end ZI moiety shows higher mobility. Similarly, when comparing Li⁺or TFSI⁻across motifs, it is seen that the respective pendant‐end counterion possesses higher mobility than its backbone‐adjacent counterpart. Furthermore, when comparing counterions to same‐position ZI moieties, TFSI⁻is seen to possess higher mobility than Li⁺in each case, a result rationalized by invoking the lower interaction strength between the TFSI⁻and ZI⁺. Analysis of ion‐transport mechanisms demonstrate that the mobility of countercharges to the pendant‐end ZI moiety correlates with the ion‐association relaxation timescale, similar to ideas noted in polymerized ionic liquids in past studies. However, the mobility of countercharges to the backbone‐adjacent ZI moiety is shown to be correlated with a cage relaxation time, which incorporates the combined effects of frustrated motion due to the presence of the polymer backbone and pendant‐end ZI moiety and the higher mobility in a population of lightly ZI‐coordinated ions. © 2020 Wiley Periodicals, Inc. J. Polym. Sci.2020,58, 578–588 

We report the results of atomistic molecular dynamics simulations on polymerized 1-butyl-3-vinylimidazolium-hexafluorophosphate ionic liquids, studying the influence of the polymer molecular weight on the ion mobilities and the mechanisms underlying ion transport, including ion-association dynamics, ion hopping, and ion–polymer coordinations. With an increase in polymer molecular weight, the diffusivity of the hexafluorophosphate (PF 6 − ) counterion decreases and plateaus above seven repeat units. The diffusivity is seen to correlate well with the ion-association structural relaxation time for pure ionic liquids, but becomes more correlated with ion-association lifetimes for larger molecular weight polymers. By analyzing the diffusivity of ions based on coordination structure, we unearth a transport mechanism in which the PF 6 − moves by “climbing the ladder” while associated with four polymeric cations from two different polymers.