Thermal Fusion of Lithium‐Philic Fluorinated Bi2O2CO3 to Derive Heterogeneous SEI and Dendrite‐Free Li Plating for the First Ah‐Level Fluoride Conversion Pouch Cells

The thermal fusion of fluorine-incorporated Bi₂O₂CO₃ with lithium metal is proposed to construct a lithium-philic artificial solid electrolyte interface that evolves into a LiF/Li₂CO₃-dominated heterostructure during cycling, enabling dendrite-free lithium deposition. The first Ah-level FeF₃//Li pouch cell is successfully assembled and operated.

ABSTRACT

The artificial solid electrolyte interface (ASEI) is regarded as a simple yet highly effective approach to enhance both the electrochemical and mechanical stability of the anode-electrolyte interface. In this study, we propose the thermal fusion of fluorine-incorporated Bi₂O₂CO₃ (F-BOC) with lithium metal to construct a lithium-philic ASEI functioning as an interface rectifier to regulate lithium-ion deposition and stripping. The introduction of fluorine promotes the Li adsorption capability of F-BOC, and the formation of an isotropic and compact structure that blocks TFSI⁻ anions outside the ASEI layer. Under sustained electrochemical operation, a heterogeneous LiF-Li₂CO₃ conductive nanodomain region is generated from F-BOC, facilitating the lithium-ion transport across the LiF-Li₂CO₃ interface, which effectively suppresses lithium dendrite growth and electrode expansion. The F-BOC-modified LiNi_0.8Co_0.1Mn_0.1O₂ full cells demonstrate excellent cycling stability, with a high capacity retention of 85.88% over 600 cycles at 1 C and a capacity retention of 90.3% over 120 cycles under high active material loading 20 mg cm⁻². Moreover, the modified thin lithium anodes (60 µm in thickness) achieve stable cycling in 15-layer pouch cells based on high-capacity FeF₃, delivering a capacity of nearly 1 Ah, which is the highest level for fluoride conversion reaction batteries.