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 Li2CO3 pollutants on the surface of the solid-state electrolyte Li6.4La3Zr1.4Ta0.6O12 (LLZTO) can hinder their commercial application by causing poor LLZTO/Li interface contact and lithium dendrite growth. Hence, the growth process of Li2CO3 on the LLZTO surface is investigated; subsequently, a safe, low-cost, and efficient method was proposed to remove Li2CO3. The method involved soaking LLZTO in pure CH3COOH 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 Omega 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 CH3COOH treatment successfully removes Li2CO3 and produces a lithiophilic LLZTO interface.