Dual‐Functional Fluorinated Additive in Gel Polymer Electrolyte for High‐Energy‐Density Anode‐Free Lithium Batteries With Enhanced Thermal Stability

Abstract

ABSTRACT Anode‐free lithium metal batteries offer high energy density and low cost, but their practical deployment is limited by unstable lithium–electrolyte interfaces and safety risks from dendrite growth and flammable electrolytes. Here, we report a dual‐functional fluorinated additive that enables in situ gelation, forming a thin, inorganic‐rich solid electrolyte interphase while simultaneously enhancing flame retardancy through radical capture. At 0.5 C discharge, the additive‐enabled anode‐free pouch cell delivers high specific capacities of 202.1 mAh/g (3.0–4.5 V) and 192.0 mAh/g (3.4–4.3 V), while retaining 80.3% and 80.1% of their initial values after 85 and 100 cycles, respectively. Moreover, Cu/NCA pouch cells with capacities of 1.4 Ah (3.0–4.5 V) and 200 mAh (3.6–4.3 V), incorporating the additive, retain 80.2% of initial capacity after 85 cycles and 92.9% after 100 cycles, respectively. Such performance is on par with or better than the best results in the literature. Impressively, such a 1.4 Ah cell shows no thermal runaway in a harsh drilling test at the fully charged state, even after 100 cycles. These results demonstrate that the dual‐functional fluorine additive leads to both excellent electrochemical performance and enhanced safety, paving the way for the safe and practical application of anode‐free lithium metal cells.