Fluorinated gel polymer electrolytes for high performance lithium metal batteries: a mechanism analysis and systematic review

Gel polymer electrolytes (GPEs) have shown great potential to improve the safety and performance of lithium metal batteries (LMBs), offering benefits such as improved mechanical properties, uniform lithium deposition, suppression of dendrite growth, and minimized electrolyte leakage. Nonetheless, several challenges persist, including the solid electrolyte interphase (SEI) instability, suboptimal ionic conductivity, inherent flammability, and an inability to operate at high voltage, significantly hindering their long-term stability and capacity retention. Given fluorine atoms’ small atomic radius and high electronegativity, fluorinated gel electrolytes (FGPEs) offer distinct advantages in mitigating these challenges. This review systematically examines the role of fluorine in enhancing the performance of GPEs, with particular emphasis on fluorine’s role in improving the SEI composition in GPEs. Additionally, the review elucidates the mechanism of thermal runaway in LMBs and investigates fluorine’s contribution to enhancing the flame retardancy of these batteries. The article also details the role of fluorinated components in facilitating lithium-ion transport and evaluates the suitability of fluorinated gel polymer electrolytes for high-voltage applications. Finally, the review elaborates on design strategies for advancing FGPEs and underscores their potential to address critical challenges in lithium metal battery technology.