Garnet-type Li6.4La3Zr1.4Ta0.6O12 thin sheet: Fabrication and application in lithium-hydrogen peroxide semi-fuel cell

An Al2O3-doped Li6.4La3Zr1.4Ta0.6O12 (LLZTO) cylinder with a cubic garnet structure was prepared by solid state reaction and pressureless sintering. The LLZTO cylinder showed a high relative density of ~ 94%. LLZTO sheets (200 μm in thickness) were obtained by slicing the LLZTO cylinder using a low speed diamond saw. Ionic conductivity of the sheet was as high as 1.02 × 10− 3 S·cm− 1 at room temperature. Two specially designed Li-H2O2 semi-fuel cells were assembled using the LLZTO sheet and LTAP sheet (from Ohara, Japan), respectively. The semi-fuel cell employing the LLZTO sheet showed a lower internal resistance and a much higher maximum power density. It discharged at a constant current of 1.0 mA for 1500 min (two “mechanical recharge-discharge” cycles), and relative flat discharge voltage plateaus of ~ 2.5 V were observed, with an average lithium metal utilization in the cell of 82.0%. The LLZTO thin sheets showed that high quality and could improve the performance of the Li-H2O2 semi-fuel cell.