Well-Dispersed Garnet Crystallites for Applications in Solid-State Li-S Batteries

A uniform ceramic tape of well-dispersed garnet-type Li_6.4La₃Zr_1.4Ta_0.6O₁₂ particles (LLZTO) with a high solid content of 70 wt % is prepared as an electrolyte in solid-state Li-S batteries. The use of appropriate dispersants is crucial for achieving fine dispersion and uniform distribution of LLZTO particles in the ceramic tape. This leads to improved surface flatness and mechanical strength of the ceramic tape. Moreover, the ionic conductivity increases remarkably at the same time from 10^-5 to 10^-4 to 10^-4 to 10^-3 S cm^-1, and the Li⁺ transport number doubles from 0.35 to 0.70. The Li-S battery constructed with the dispersed LLZTO electrolyte shows an adequate capacity of above 600 mA h g^-1 after 100 cycles at a discharge current of 84 mA g^-1, and it is capable of charging/discharging at a high current of 1672 mA g^-1. In comparison, the battery with a nondispersed LLZTO electrolyte functions only at the lower current of 84 mA g^-1 and fails to work after 25 cycles.