Impact of Spatial Interactions in Polycarbonate-Based Electrolytes on Ion Transport Dynamics and Battery Performance

Polymer electrolytes (PEs) show great promise in next-generation solid-state batteries. The interactions between functional monomers and lithium salts in PEs remain ambiguous, constraining the material design strategy aimed at optimizing the electrochemical performance. Here, we report on the local spatial interactions among the components in polycarbonate-based electrolytes, as determined through nuclear magnetic resonance (NMR) techniques. We used molecular dynamics simulations to rationalize the spatial distribution of ions and its effect on the coordination of anions and cations. The local dynamics of the anions and cations were further revealed from an ion dynamics perspective using variable temperature NMR techniques, shedding light on how ion mobility is affected by different spatial interactions. Finally, we clearly delineate how battery performances are affected by local spatial interactions. Our findings provide direct experimental evidence, revealing how spatial interactions affect ion diffusion dynamics at the molecular level. Overall, this work provides valuable guidance for the design and mechanistic understanding of PEs.