Lithium secondary battery equipped with a lithium metal electrode

LiF-Rich SEI Lithium Metal Battery Based on FEC Mixed Solvent and Triple Lithium Salt Electrolyte

This technology forms a LiF-rich SEI layer on the lithium metal anode surface using an electrolyte that incorporates LiPF6, LiTFSI, and LiDFOB complex lithium salts into a mixed solvent of FEC and dialkyl carbonate at a specific volume ratio. This suppresses lithium dendrite growth and enhances anode interface stability.

Lithium metal anodes have historically faced issues with uneven lithium deposition during charging, leading to dendrite growth and battery short circuits. Furthermore, surface side reactions cause the accumulation of dead lithium and electrolyte depletion, which limits battery lifespan and energy efficiency.

This technology utilizes an electrolyte formulated with 2.7 to 3.3 parts by volume of dialkyl carbonate (such as EMC) per 1 part by volume of FEC, combined with 0.03–0.07M LiPF6, 0.75–0.95M LiTFSI, and 0.05–0.25M LiDFOB. This creates a functional SEI layer composed of organic/inorganic hybrid components like LiF, PEO, Li2CO3, Li2S, and Li3N to protect the anode. Applicable to high-energy-density lithium metal pouch cells, lightweight power sources for drones/UAM, and next-gen electrolytes, it addresses dendrite issues through electrolyte formulation alone, eliminating the need for separate anode coating processes.

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Key Features:

• An electrolyte disposed between an anode comprising a lithium metal or lithium alloy layer and a cathode
• A carbonate-based mixed solvent containing 2.7 to 3.3 parts by volume of dialkyl carbonate per 1 part by volume of FEC
• A lithium salt combination of 0.03 to 0.07M LiPF6, 0.75 to 0.95M LiTFSI, and 0.05 to 0.25M LiDFOB
• An SEI layer located between the anode and the electrolyte, where the LiF peak area is equal to or greater than the C-F peak area in F1s XPS

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This invention was developed with support from the Ministry of Science and ICT for the development of core technologies for high-energy-density lithium metal batteries based on the design of natural organic/inorganic composite membrane formation reactions.

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