ZnO Grain-Interlayer Fabrication for Suppressing the Mixed Ionic–Electronic Conducting Interphase for Solid-State Lithium Batteries

Li1.3Al0.3Ti1.7(PO4)3 (LATP) is a promising solid electrolyte material due to its stability in ambient conditions and cost-effectiveness. Moreover, its high shear modulus hinders lithium dendrite growth in lithium metal batteries. Nevertheless, an undesired side reaction occurring between lithium metal and LATP contributes to battery degradation. In this study, we propose a simple method to infiltrate zinc oxide into LATP, aiming to enhance the stability of the interface between lithium metal and LATP. The infiltration process involves the immersion of the LATP electrolytes in the zinc nitrate precursor solution followed by calcination, leading to the formation of a zinc oxide grain interlayer. The ZnO grain interlayer at the Li metal interface forms an ionic conductive Li2O solid electrolyte interphase, thereby significantly mitigating the side reaction between Li and LATP. Additionally, the ZnO grain-interlayer intraelectrolyte facilitates the movement of Li+ ions and inhibits Li dendrite growth. The Li/ZnO-LATP/Li symmetric battery exhibits stable cycling performance over 120 h without noticeable degradations, whereas the pure LATP configuration (Li/LATP/Li) exhibits significant performance degradation in a few hours at a current density of 0.05 mA cm–2. Overall, our findings highlight the novel zinc oxide infiltration technique to form a protective grain interlayer for efficiently enhancing the stability of solid-state electrolytes.