Integration of Oxide-Based All-Solid-State Batteries at 350°C by Infiltration of a Lithium-Rich Oxychloride Melt

We highlight the lowest-temperature manufacturing of oxide-based all-solid-state batteries in this study. A lithium-rich oxychloride melt was employed to integrate Li_6.25Ga_0.25La₃Zr₂O₁₂ (Ga-LLZO) solid electrolyte particles and LiCoO₂ cathode-active particles at 350°C. As observed by X-ray diffraction, scanning electron microscopy, and microcomputed tomography, the infiltration and subsequent solidification of the melt can promote interparticle contact without chemical crosstalk in the cathode and across the cathode–solid electrolyte interface. The melt-infiltrated all-solid cathode exhibits respectable capacity, 83 mA h g⁻¹ at 90°C. Due to mechanical degradation of the interfaces, the cathode failed to maintain good cycle stability. Given that the minute amount of liquid electrolyte addition leads to substantial improvement of achievable capacity (106 mA h g⁻¹ at RT) and capacity retention, ensuring electric wiring in the cathode is key to achieving desirable electrochemical properties of the all-solid cells produced by the melt-infiltration process. Identified cathode optimization to better leverage this melt-infiltration approach includes, but is not limited to, engineering particle size distribution of Ga-LLZO and LiCoO₂ and configurations of the cathode components. While our proposed method is yet to be perfected, we have established a practical foundation to integrate oxide-based all-solid-state batteries.