Oriented Attachment Strategy Toward Enhancing Ionic Conductivity in Garnet-Type Electrolytes for Solid-State Lithium...

Solid-state lithium batteries (SSLBs) based on garnet-type solid-state electrolytes (SSEs) have attracted much attention due to their high energy density and chemical stability. However, poor room-temperature ionic conductivity and low density of SSEs induced by conventional preparation routes limit their potential future applications. In this work, an oriented attachment strategy is employed to enhance the Li-ion conductivity and density of garnet-type SSE Li_6.5La₃Zr_1.5Ta_0.5O₁₂ by introducing La₂O₃ nanoparticles. The oriented attachment of the ZrO₂(Ta₂O₅) matrix mediates the epitaxial growth of the La-Zr(Ta)-O intermediate phase due to the addition of La₂O₃ nanoparticles. Continuous Li-ion transport pathways along grain boundaries are produced by the combination of residual La₂O₃ and gas Li₂O. A densification interface is obtained when 10 wt % La₂O₃ is doped. The maximum value of Li-ion conductivity reaches 8.20 × 10^-4 S·cm^-1, with a relative density of 97.3%. SSLBs with a LiFePO₄ cathode showing a stable cycling performance with a discharge capacity of 123.1 mA·h·g^-1 and a Coulombic efficiency of 99.2% after 300 cycles (0.5C) at room temperature. This work is comparable to the state-of-the-art methodology, which provides a feasible approach to creating SSEs with high performances for SSLBs.