Ion-conducting block copolymers (BCPs) have attracted significant interest as conducting materials in solidstate lithium batteries. BCP self-assembly offers promise for designing ordered materials with nanoscale domains. Such nanostructures provide a facile method for introducing sufficient mechanical stability into polymer electrolyte membranes, while maintaining the ionic conductivity at levels similar to corresponding solvent-free homopolymer electrolytes. This ability to simultaneously control conductivity and mechanical integrity provides opportunities for the fabrication of sturdy, yet easily processable, solid-state lithium batteries. In this review, we first introduce several fundamental studies of ion conduction in homopolymers for the understanding of ion transport in the conducting domain of BCP systems. Then, we summarize recent experimental studies of BCP electrolytes with respect to the effects of salt-doping and morphology on ionic conductivity. Finally, we present some remaining challenges for BCP electrolytes and highlight several important areas for future research.

We present the design of novel solid electrolytes using tapered block polymers (TBPs). In this work, we synthesize a series of TBPs via atom transfer radical polymerization (ATRP) consisting of rigid polystyrene and ion-conducting poly(oligo-oxyethylene methacrylate) segments and explore the role of tapered interfaces on ion transport. Previous studies on TBPs have shown that manipulating the taper composition in block polymers can reduce the unfavorable polymer-polymer interactions between blocks, enabling the design for highly-processable (lower order-disorder transition temperature) polymer electrolytes. Herein, we demonstrate that the taper profile and taper volume fraction significantly impact the glass transition temperatures (T g s) in block polymer electrolytes, thus affecting the ionic conductivity. Additionally, we find that the normal-tapered materials with z60 vol% tapering exhibit remarkable improvements in ionic conductivity (increase z190% at 20 C and increase z90% at 80 C) in comparison to their non-tapered counterparts. Overall, our TBPs, with controllable interfacial interactions, present an exciting opportunity for the fabrication of cost-effective, highly-efficient, and stable energy storage membranes.

Abstract