Superionic Conductivity in Polyzwitterion-Based Polymer Electrolytes

Polymer electrolytes are promising candidates for next-generation solid-state batteries due to their high flexibility, improved electrochemical stability, and ease for processing. However, the most polymer electrolytes suffer from low ionic conductivities (<< 1 mS/cm). This talk presents studies of the ion transport in three different polymerized zwitterions i.e., polyzwitterions (PZIs) doped with LiTFSI across a wide range of temperatures. For all three PZIs, the timescale for motion of ionic rearrangements at the glass transition temperature (T_g) was found to be around 10^-7 sec or even faster, highlighting significant decoupling of ion mobility from the polymer structural relaxation (~10² sec at T_g). Consequently, the ionic conductivities of the three PZIs at T_g were found to be as high as 10^-3-10^-4 S/cm and comparable to conductivity of superionic ceramics. This remarkable conductivity is attributed to the formation of concentrated ion channels in PZIs, as proposed recently [1]. Our findings provide key insights into the design of polymer electrolytes with enhanced ion transport properties and highlight the potential of polyzwitterions as promising materials for solid-state battery and other energy storage applications.