Bisphenol-Derived Single-Ion Conducting Multiblock Copolymers as Lithium Battery Electrolytes: Impact of the Bisphenol Building Block

Poly(arylene ether sulfone)-derived single-ion conducting (SIC) block copolymers are promising candidates as (solid) electrolytes for lithium-metal batteries owing to their high electrochemical stability and structural versatility. When incorporating small organic molecules (e.g., organic carbonates such as ethylene carbonate, EC), high ionic conductivities can be reached even at ambient temperatures. To gain further insights into the impact of the polymer backbone chemistry on the physicochemical and electrochemical properties, a series of SIC multiblock copolymers were synthesized comprising bisphenol-derived monomers for the ionophilic block. All of these SIC block copolymers (containing 55 wt % of EC) show high ionic conductivities. Remarkably, though, the electrochemical stability toward oxidation is slightly decreasing for an increasing size of the substituent at the central carbon atom of the bisphenol monomer, whereas the overpotential for lithium stripping and plating is decreasing. These results highlight the importance of carefully designing the polymer backbone for high-performance lithium battery electrolytes.