Fabrication of Li7La3Zr2O12 films with controlled porosity and fast Li+ transport

Free-standing Ga-doped Li7La3Zr2O12 (LLZO) films are fabricated by a scalable tape casting technique. The thin (25–50 μm) ceramics exhibit a relative density of 98 ± 1 % and record-high ionic conductivity (1.41 ± 0.05 mS cm−1) for tape cast LLZO. A solution-based approach is used to synthesize the green powders which enable sintering at relatively low temperatures (1050 °C, 30 min). The phase chemistry and microstructure are well-controlled during the sintering process. The tapes are further developed into multilayer porous/dense/porous structures to provide a fast Li+ conducting ceramic framework for all-solid-state batteries (ASSBs). X-ray micro computed tomography (microCT) analysis reveals a fully interconnected pore network in the outer porous layers. In addition, the multilayer structures exhibit a critical current density (CCD) of 2.5 mA cm−2 at room temperature and are stable over 200 cycles at a current density of 0.5 mA cm−2 in symmetric Li cells. Overall, this work offers guidance for the scalable production of thin LLZO ceramics with enhanced physical and electrochemical properties.