Enhanced mechanical strength and ionic conductivity of LLZO solid electrolytes by oscillatory pressure sintering

Abstract

Abstract Oscillatory pressure sintering (OPS) is a novel sintering technique which can promote the densification of ceramic samples due to a periodic fluctuant pressure applied during sintering. In this work, OPS was successfully adopted to prepare Li-garnet solid electrolytes (Li6.4La3Zr1.4Ta0.6O12) for the first time. Compared with the sample sintered by conventional hot-pressing (HP), the solid electrolytes sintered by OPS have higher density and finer grain structure, and consequent higher mechanical properties as well as higher Li+ ion conductivity. The results indicate that the LLZO electrolytes fabricated by OPS process have improved mechanical properties, 241 ± 20 MPa of bending strength, 2.89 ± 0.13 MPa m1/2 of fracture toughness and 8.69 ± 0.33 GPa of Vickers hardness. Meanwhile, the electrolytes possess high conductivity at room temperature of 4.43 × 10−4 S cm−1. High strength and high conductivity are attributed to the rapid densification and the inhibited grain growth induced by the oscillatory pressure.