Controlled ionic conductivity via tapered block polymer electrolytes

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_gs) in block polymer electrolytes, thus affecting the ionic conductivity. Additionally, we find that the normal-tapered materials with ≈60 vol% tapering exhibit remarkable improvements in ionic conductivity (increase ≈190% at 20°C and increase ≈90% 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.