Tuning porous Li_6.25Ga_0.25La₃Zr₂O₁₂(LGLZO) frameworks for enhanced ion transport in semi-solid-state lithium metal batteries

Lithium metal is considered an ideal anode material owing to its high specific capacity, low density, and low redox potential, but its practical use in liquid systems is hindered by dendrite growth and interfacial instability. Solid-state electrolytes (SSEs) offer high thermal stability and mechanical strength, with Li₇La₃Zr₂O₁₂ (LLZO) being particularly attractive for its high ionic conductivity and wide electrochemical window. Semi-solid-state electrolytes (SSSEs), integrating the advantages of SSEs and liquid electrolytes (LEs), can be further enhanced by introducing porous solid frameworks. Such structures improve interfacial wettability and ion transport while providing mechanical support that suppresses dendrites, thereby achieving both high conductivity and structural safety. In this work, a two-dimensional porous solid-state skeleton model was established to investigate the influence of porosity on lithium-ion transport. The percolation threshold was determined to be 47.91% porosity, indicating the minimum connectivity required for efficient ion migration. Based on these insights, a graphite-template sacrificial method was employed to fabricate a highly interconnected porous Li_6.25Ga_0.25La₃Zr₂O₁₂ (LGLZO) framework (P_GLF). The ionic conductivity of the P_GLF-LiPF₆ SSSE reached 3.02 × 10⁻³ S cm⁻¹ at room temperature. The constructed Li/Li cell can be stably cycled for more than 1600 h at 0.5 mA cm⁻², and the capacity retention rate of the LFP/Li cell was 91.62% after 2000 cycles at 2 C. This work established a correlation between porosity and ion transport performance, providing a promising preparation method for high-performance lithium metal batteries (LMBs).