Low-sintering-temperature garnet oxides by conformal sintering-aid coating
Shaojie Chen, Xiangchen Hu, Wenda Bao, Zeyu Wang, Qun Yang, Lu Nie, Xun Zhang, Jingxuan Zhang, Yilan Jiang, Yi Han, Chunlei Wan, Jin Xie, Yi Yu, Wei Liu
Abstract
Garnet-type solid electrolytes have attracted extensive attention for solid-state lithium (Li) batteries. However, the high processing temperature of up to 1,200°C limits large-scale production. Here, we report a simple approach to reduce the sintering temperature by using a conformal nanoscale amorphous alumina coating. The ceramic sintered at 980°C shows a high room temperature ionic conductivity of 0.13 mS cm−1. It reveals that the second phases segregated at grain boundaries are ionically conductive but electronically blocking, which can block electronic conduction and improve mechanical property. The Li symmetry cells indicate a long-term 2,500-cycle life and a high critical current density of 0.52 mA cm−2. The garnet electrolyte enables the high-voltage cells using Li1.2Ni0.2Mn0.6O2 to deliver a high specific capacity of 248 mAh g−1 at 0.05 C. This work provides a new clue for lowering sintering temperature for garnet electrolytes, which can extend to other ceramics toward practical applications.