Ballistic Ion Transport Through Hierarchically-ordered-structure Polymer Binder
Ballistic Ion Transport Through Hierarchically-ordered-structure Polymer Binder
Abstract
Since its discovery in the 1970s, solid-state ion conduction within polymers has primarily relied on polymer segmental motion to drive ion diffusion. However, ion transport based on polymer dynamics features low ionic conductivity (usually < 10-5 S/cm) at room temperature and highly depends on temperature, which influences performance by controlling the ratio of amorphous to crystalline composition in polymers. A faster ion transport mechanism, independent of polymer dynamics, has long been sought but remains inaccessible. We discover a ballistic ion transport mechanism in a mixed electronic-ionic conductive (MEIC) polymer binder, where its hierarchically ordered structure facilitates ion diffusion and achieves solid-state Li+ conductivity in the range of 10-4 to 10-3 S cm-1 from -20 to 70 °C. This mechanically robust MEIC polymer is a versatile ionic conductor, allowing Li+, Na+, or K+ to diffuse through polymer matrix, with their cationic charges counterbalanced by electrons on conjugated polymer backbones. Traditional polymer binders have typically been classified as inactive materials due to their negligible capacity. In contrast, this polymer binder features a high Li+ ion capacity, transforming it into an active material and providing a method to enhance energy density. This work establishes a foundation and inspires a design principle for engineering multifunctional polymer binders with superionic conductivity, high electronic conductivity, high capacity, and mechanical robustness, thereby extending their applications in the field of solid-state energy.
Speaker
Defu LiDefu Li, Ph.D., is currently a postdoctoral scholar in Dr. Gao Liu’s research group within the Energy Storage and Distributed Resources Division (ESDR) at Lawrence Berkeley National Laboratory. His current research focused on three key areas: (1) developing multifunctional mixed electronic-ionic conductive polymer binders for high-energy-density lithium-ion batteries, sodium-ion batteries, and all-solid-state batteries, (2) studying the fundamental properties, polymer physics, and ion transport mechanisms of polymers for energy storage applications, (3) investigating the calendar aging process of high-energy-density silicon-based lithium-ion batteries. He earned his Bachelor of Science degree in Chemical Engineering from the University of California, Los Angeles (UCLA) in 2017, and subsequently completed his Doctor of Philosophy (Ph.D.) in the same field at UCLA in 2022. His graduate research, conducted in Prof. Samanavaya Srivastava's group, concentrated on the polymer physics, structural dynamics, mechanical properties, and bioadhesive applications of polyelectrolyte complex-interpenetrating polymer network (PEC-IPN) hydrogels.