2D flake-like garnet electrolytes for solid-state lithium metal batteries

Solid state lithium metal batteries exhibit a great potential for future energy storage due to the merits of high energy density and enhanced safety. However, undesired lithium dendrites growth greatly limits the practical applications. The microstructural regulation of solid-state electrolytes (SSEs) is considered an effective strategy. In particular, the two-dimensional (2D) morphological design of the electrolyte with a physical shielding effect is emerging as a feasible route to inhibit the growth of lithium dendrites. Especially, it can form a soft-rigid hybrid structure when used in composite electrolyte, which is beneficial for further building a physical shield barrier against lithium dendrites. However, SSEs with 2D microstructure are rarely reported due to the lack of mature preparation methods. Herein, a facile optimized co-precipitation method is proposed to fabricate ultrathin (∼300 nm) 2D flake garnet-type Li_6.4Al_0.2La₃Zr₂O₁₂ (2D-LALZO). In addition, the synthetic details along with its underlying mechanisms are illuminated through experimental verifications and theoretical speculations, which can be ascribed to the synergistic precipitation of two-dimensional CDs complexes. The as-constructed composite solid electrolyte exhibits increased ionic conductivity and mechanical strength, which achieves a uniform deposition/stripping of lithium metal and long lifespan over 500 h at 0.2 mA/cm², 0.2 mA h/cm². Moreover, the assembled LiFePO₄/Li full cell exhibits a superior cycling stability with 98 % capacity retention after 120 cycles at 0.1C.