New hybrid electrolyte for high performance Li-ion batteries

This article reports the development of a hybrid polymeric solid electrolyte designed to enhance the safety and performance of lithium-ion batteries (LIBs). Conventional liquid and gel electrolytes based on organic solvents such as ethylene carbonate provide high ionic conductivity and wide electrochemical stability but suffer from flammability, posing safety risks in applications such as smartphones and electric vehicles. Solid polymer electrolytes, exemplified by polyethylene glycol (PEG), offer improved mechanical robustness and non-flammability; however, their practical implementation has been hindered by crystallization near room temperature, which reduces ionic conductivity to ~10⁻⁶ S/cm. To address this limitation, the authors combine a photo-cross-linkable PEG-based polymer with a porous polymer membrane possessing micrometer-scale pores, forming a composite “honeycomb” electrolyte. This hybrid architecture achieves a wide electrochemical window of 4.7 V, room-temperature Li-ion conductivities in the 10⁻⁴ S/cm range—comparable to liquid electrolytes—and a relatively high Li-ion transference number of 0.39. The porous structure constrains ion transport pathways, mitigating non-linear diffusive motion over micrometer length scales and thereby enhancing effective conductivity. In addition to improved electrochemical performance, the inclusion of a mechanically robust porous membrane is anticipated to suppress lithium dendrite formation, reducing the risk of internal short circuits and ignition. The work thus provides a promising route toward safer, high-performance solid-state LIBs, contributing to sustainable energy technologies aligned with global development goals.