Recent Advances in Poly(ethylene oxide)-Based Solid-State Electrolytes for Lithium-Ion Batteries

Poly­(ethylene oxide) (PEO)-based solid polymer electrolytes are pivotal in advancing high-energy-density solid-state battery technology, particularly for lithium-ion and other rechargeable batteries. PEO-based polymer electrolytes are regarded as promising due to their high conductivity and stability. However, conventional linear PEO exhibits limited ionic conductivity, attributed to the high crystallinity of the ethylene oxide (EO) chains. This crystallinity impedes ion migration, particularly at low temperatures. Various strategies have been employed to reduce the crystallinity of PEO to enhance the ionic conductivity of PEO-based electrolytes. Moreover, the electrochemical window and compatibility with both electrodes are critical. Scientists have investigated diverse approaches to enhance interfacial performance with electrodes for better electrochemical stability. This Review summarizes the latest research advancements in PEO-based solid polymer electrolytes for lithium-ion batteries, emphasizing enhancements in ionic transport properties, mechanical performance, electrochemical stability, structural design optimization, and the exploration of new PEO-based electrolyte systems. Finally, the challenges and future prospects of these materials are discussed.