Direct Precursor Route for the Fabrication of LLZO Composite Cathodes for Solid‐State Batteries

Solid–state batteries based on Li$_7$La$_3$ Zr$_2$ O$_{12}$ (LLZO) garnet electrolyte are a
robust and safe alternative to conventional lithium-ion batteries. However, the
large-scale implementation of ceramic composite cathodes is still challenging
due to a complex multistep manufacturing process. A new one-step route for
the direct synthesis of LLZO during the manufacturing of LLZO/LiCoO$_2$ (LCO)
composite cathodes based on cheap precursors and utilizing the industrially
established tape casting process is presented. It is shown that Al, Ta:LLZO
can be formed directly in the presence of LCO from metal oxide precursors
(LiOH, La$_2$ O$_3$ , ZrO$_2$ , Al$_2$ O$_3$ , and Ta$_2$ O$_5$ ) by heating to 1050 °C, eliminating the time- and energy-consuming synthesis of preformed LLZO powders. In
addition, performance-optimized gradient microstructures can be produced
by sequential casting of slurries with different compositions, resulting in
dense and flat phase-pure cathodes without unwanted ion interdiffusion or
secondary phase formation. Freestanding cathodes with a thickness of 85 μm,
a relative density of 95%, and an industrial relevant LCO loading of 15 mg
... mehr
show an initial capacity of 82 mAh g$^{-1}$ (63% of the theoretical capacity of
LCO) in a solid-state cell with Li metal anodes, which is comparable to
conventional LCO/LLZO cathodes and can be further improved in the future.