Development of solid polymer electrolytes for solid-state lithium battery applications

Nowadays, the safety concern for lithium batteries is mostly on the usage of flammable electrolytes and the lithium dendrite formation. The emerging solid polymer electrolytes (SPEs) have been extensively applied to construct solid-state lithium batteries, which hold great promise to circumvent these problems due to their merits including intrinsically high safety, good stability and high capacity of lithium (Li) metal. Single-ion conducting polymer electrolytes (SICPEs) have great advantages over traditional SPEs due to their high lithium transference numbers (LTN) (near to 1). SICPEs improves the overall performance of the battery by suppressing both concentration polarization and impedance. Herein, this review is to offer timely update of the development of SPEs for solid-state lithium battery applications. Generally, the fundamental principles, classification, key parameters, and ion transport mechanisms of SPEs are summarized, followed by the discussion on the modification method. Furthermore, for SICPEs, a special focus is on synthesis and tuning of negative charge dispersion. In addition, artificial intelligence (AI) and machine learning (ML) in material design for SPEs are pointed out. Moreover, we bring up the challenges and offer solutions for further development of SPEs in solid-state lithium batteries.