Low-Temperature Fabrication of Bulk-Type All-Solid-State Lithium-Ion Battery Utilizing Nanosized Garnet Solid Electrolytes

Garnet-type Li7La3Zr2O12 (LLZ) materials are attracting attention as solid electrolytes (SEs) in oxide-based all-solid-state batteries (ASSBs) owing to their high ionic conductivity. Although the electrochemical stability of LLZ against Li metal is demonstrated with possible high energy density, high-temperature sintering above 1000 degrees C, which is required to achieve high Li-ion conductivity, results in the formation of insulating impurities at the electrode-electrolyte interfaces. Here, nanosized fine-particle samples of Ta-substituted Li6.5La3Zr1.5Ta0.5O12 (LLZT) are successfully prepared at a remarkably low temperature of 400 degrees C utilizing an amorphous precursor oxide. The dense LLZT SE sintered by hot pressing at 500 degrees C shows room-temperature Li-ion conductivity of 1.03 x 10(-4) S cm(-1) without any additives. In addition, the bulk-type NCM-graphite full battery cell fabricated with the LLZT fine particles through a hot-pressing sintering method at 550 degrees C exhibits a good charge-discharge performance at room temperature with the bulk-type areal discharge capacity of 0.831 mAh cm(-2). The nanosized garnet SE strategy demonstrated in this study paves the way for the formation of oxide-based ASSBs by low-temperature sintering.

Automated summary

Nanosized Ta-substituted Li6.5La3Zr1.5Ta0.5O12 (LLZT) samples were successfully prepared at a low temperature of 400 degrees C and showed high room-temperature Li-ion conductivity. The LLZT fine particles were used to fabricate a bulk-type NCM-graphite full battery cell, which exhibited good charge-discharge performance at room temperature. This study provides a new approach for the fabrication of oxide-based all-solid-state batteries through low-temperature sintering.