LLZO for batteries from powder synthesis to 3D printing
BLUGAN G. 1, KARUPPIAH D. 1, KOMISSARENKO D. 1, HADIAN A. 1, CLEMENS F. 1
1 Empa, Laboratory for High Performance Ceramics, Dübendorf, Switzerland
An inorganic solid electrolyte is the most favorable candidate for replacing flammable liquid electrolytes in lithium batteries. Generally, Lithium Lanthanum Zirconium Oxide (LLZO) is one of the most promising solid electrolytes owing to its safe operating potential window (0-5V) with good electrochemical stability. In this work, we synthesize 250 g of phase pure cubic Ta-doped (Li7La3Zr1.6Ta0.4O12) per batch by optimizing two-step thermal treatment. The first step thermal treatment at 950 °C started initiation of the nucleation of the LLZO by fixing the processing parameters like heating atmosphere, temperature, dopant concentration. The next-step thermal treatment at 1150 °C allowed us to obtain the sintered disca (solid electrolyte) with a relative density of 96%. From the XRD, the phase purity and the lattice parameter (12.9250 Å) of the Ta-LLZO disc was confirmed from the refined data. Further, the presence of dopant Ta in the disc could be analysis through XPS analysis. Microstructural imaging of the disc was observed the formation of grains and their boundaries. The ionic and electronic and conductivity values of the solid-state electrolyte (Ta-LLZO) disc were 10-4 S cm-1 and 10-10 S cm-1, respectively. These values could agree that the prepared solid electrolyte (Ta-LLZO) disc have exhibited ionically conducting and electronically insulation nature. Finally, the critical current density measurements were also carried out for the disc up to 0.12 mA cm-2.
The next big challenge in the LLZO ceramic based solid electrolyte is very difficult to customize its shape. As well as tape casting, we show here that the customized shape and size of solid electrolyte LLZO can be achieved using Digital Light processing (DLP) 3D printing technique. To achieve this formation, we can optimize the slurry preparation, 3D-printing parameters, de-binding process and sintering process. Finally, we carried out the electrochemical performance for the 3D printed disc. This study could motivated further research toward 3D printing customized LLZO batteries.