<p>All-solid-state batteries with inorganic solid electrolytes are a global trend in the development of next-generation energy storage devices, promising greatly simplified designs, increased energy density, and, perhaps most importantly, enhanced safety. Currently, the anion-mixed strategy for all-solid-state batteries is the mainstream for developing amorphous halide solid electrolytes, opening up good possibilities for creating conductors with high ionic conductivity and stability. Here, we show the structure evolution of amorphous solid electrolyte, Li_3xZrCl₄N_x (0.17 ≤ x ≤ 1), demonstrating ionic conductivities of up to 3.21 × 10^-3 S∙cm^-1 at 30°C, suggesting that the formation of nitrogen-containing frameworks is crucial for enhancing ionic conductivity. The structural evolution during the mechanochemical reaction, revealed by in situ time-resolved synchrotron X-ray diffraction, highlights the advantages of mixed-anion chemistry and clarifies the formation pathway of the dual-anion electrolyte. In addition, nitrogen incorporation into amorphous electrolyte provides enhanced mechanical deformability and leads to promising electrochemical performance over a wide temperature range. In particular, the dual-anion solid electrolyte maintains stable operation at lower temperatures when coupled with a LiIn negative electrode, highlighting the broader potential of anion-mixed design for all-solid-state batteries.</p>