Electrochemical energy storage is one of the main societal challenges of this century. The performances of classical lithium-ion technology based on liquid electrolytes have made great advances in the past two decades, but the intrinsic instability of liquid electrolytes results in safety issues. Solid polymer electrolytes would be a perfect solution to those safety issues, miniaturization and enhancement of energy density. However, as in liquids, the fraction of charge carried by lithium ions is small (<20%), limiting the power performances. Solid polymer electrolytes operate at 80 °C, resulting in poor mechanical properties and a limited electrochemical stability window. Here we describe a multifunctional single-ion polymer electrolyte based on polyanionic block copolymers comprising polystyrene segments. It overcomes most of the above limitations, with a lithium-ion transport number close to unity, excellent mechanical properties and an electrochemical stability window spanning 5 V versus Li(+)/Li. A prototype battery using this polyelectrolyte outperforms a conventional battery based on a polymer electrolyte.

A new family of single-ion-conductor block-copolymer electrolytes (BCEs), comprising poly(ethylene oxide) (PEO) as conducting block and poly(styrene sulfonyl(trifluoromethanesulfonyl) imide of lithium) (PSTFSI) as structural block, was developed recently. To evaluate the influence of the structural blockon the physico-chemical and electrochemical properties, we compare two single-ion-conductor BCE families with structural blocks made of either PSTFSI or poly(3-sulfonyl(trifluoromethanesulfonyl) imide propyl methacrylate of lithium) (PMATFSI). Small-angle X-ray scattering revealed that at temperatures lower than the PEO block melting temperature, the morphology of both families is lamellar whereas, at higher temperatures, the electrolytes are in a disordered state. Both electrolyte families present an ionic conductivity maximum for some weight fraction of the structural block (w BTFSI ), named BTFSI. For w BTFSI > 0.17, the ionic conductivity of the PMATFSI-based electrolytes is larger than that of the PSTFSI-based electrolytes by at least a factor of two. Based on a detailed transport analysis, we show that the strong increase of the glass transition temperature is the main factor limiting the ionic conductivity. We also interpret the conductivity maximum of the PSTFSI-based electrolytes by a limitation in available free charges for w PSTFSI > 0.17 while the polymer dynamics slows down. The optimization of the ionic transport in this type of single-ion-conductor BCE requires promoting the compatibility of the Li þbearing structural block with the conducting block.

A series of water-soluble styrene and propyl (meth)acrylate based monomers bearing a sulfonyl(trifluoromethane sulfonyl) imide (STFSI) group was prepared.