Growth Process and Removal of Interface Contaminants for Garnet-Based Solid-State Lithium Metal Batteries

Garnet-based solid-state batteries are considered as the next-generation energy storage system due to their high energy density and nice safety. However, the growth of Li 2 CO 3 pollutants on the surface of the solid-state electrolyte Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) can hinder their commercial application by causing poor LLZTO/Li interface contact and lithium dendrite growth. Hence, the growth process of Li 2 CO 3 on the LLZTO surface is investigated; subsequently, a safe, low-cost, and efficient method was proposed to remove Li 2 CO 3 . The method involved soaking LLZTO in pure CH 3 COOH for 1 min, and this treatment changed LLZTO from being lithiophobic to lithiophilic, significantly reducing the interface resistance of LLZTO/Li from 5542 to 5 Ω cm 2 . The critical current density of the Li/LLZTO/Li symmetric cell is increased from 0.33 to 0.73 mA cm –2, and Li/LLZTO/Li could operate stably at a current density of 0.1 mA cm –2 for over 1100 h. The Li/LLZTO-HAc/LFP full cell exhibits a superior electrochemical performance, thus demonstrating the feasibility of utilizing LLZTO-HAc. These results demonstrate that this safe, low-cost, and efficient CH 3 COOH treatment successfully removes Li 2 CO 3 and produces a lithiophilic LLZTO interface.