Enhanced Densification and Conduction Properties of Li5+xLa3Nb2-xZrxO12 Garnet Solid-State Electrolytes Through Zn Doping on the Nb/Zr Site

While garnet Li ion conductors are attracting considerable interest as potential solid state electrolytes for Li ion batteries, a key challenge is to improve the conductivity, which is associated with the Li content in the structure, and to overcome the challenges of sintering dense electrolyte membranes. In this work we show that Zn doping on the 16a octahedral Nb site leads to substantially improved sintering in both Li5La3Nb2O12 and Li6La3ZrNbO12. As a result of the enhanced sintering, and the associated increase in Li content, the conductivities in both garnet systems were significantly enhanced on Zn doping, up to 2.1 x 10-4 Scm-1 at 25 oC for Li6.6La3ZrNb0.8Zn0.2O12. This doping strategy therefore represents a promising approach to improve the relative density and, hence, ionic conductivity of garnet solid state electrolyte materials for possible solid-state battery applications.