New polymer design unlocks faster ion flow in safer batteries

Researchers have addressed a critical limitation in polymeric ionic liquids (PILs), safer nonflammable electrolytes for lithium-ion batteries, which traditionally suffer from poor ion conductivity due to structural defects. PILs offer a safer alternative to conventional flammable liquid electrolytes but tend to be mechanically too soft for practical use. To overcome this, the team created block copolymers by combining PILs with a rigid polymer, leading to self-assembled nanoscale lamellar structures that enhance both mechanical strength and ion transport. However, imperfections in these nanostructures—referred to as "dead ends"—trap ions and reduce conductivity. By systematically studying these defects, the researchers developed design guidelines to minimize structural imperfections, significantly boosting ionic conductivity by up to tenfold while preserving material stability. Their findings clarify how the nanoscale arrangement of ionic components affects spacing, mobility, and overall performance. This improved understanding enables the design of PIL block copolymers that maintain their ordered structure under practical conditions,