Dendrite-suppressed garnet-amorphous glass biphasic electrolyte via in-situ liquid phase sintering for high-performance solid-state batteries

Garnet-type Li_6.5La₃Zr_1.5Ta_0.5O₁₂ (LLZTO) is a promising solid electrolyte for next-generation solid-state batteries, offering high stability against lithium and superior ionic conductivity. However, Li⁺ deposition at near-surface micropores critically triggers electrolyte fracture and lithium dendrite propagation. To overcome the limitation, a novel garnet-amorphous glass biphasic structure of LLZTO electrolyte with high ionic conductivity was fabricated through an in-situ liquid-phase sintering process. The amorphous glass phase establishing atomic-level bonding with LLZTO grains, originates from the solidification of active liquid phase formed in situ during sintering and eventually achieves homogeneous distribution at LLZTO grain triple junctions which effectively eliminates bulk and near surface micropores throughout the electrolyte. Benefitting from the biphasic structure, the critical current density (CCD) of Li|LLZTO|Li symmetric cells were significantly enhanced from 0.5 mA cm^-2 to 1.0 mA cm^-2. Furthermore, full cells paired with LiNi_0.6Co_0.2Mn_0.2O₂ cathode retain 99 % capacity retention after 100 cycles. This work innovatively presents a novel biphasic structure electrolyte formation mechanism of eliminating near-surface micropores, offering a new strategy for suppressing lithium dendrite growth.