Enhanced comprehensive performance of the LLZO series solid electrolyte via multifunctional additive

This paper elucidates the mechanism of BN as sintering additive and the enhancement for LLZO performance. The introduction of the sintering additive boron nitride (BN) to Li6.25Ga0.25La3Zr2O12 (LGLZO) can effectively eliminate the insulating phase Li2CO3 and form the liquid phase Li3BO3 along the grain boundaries, which significantly enhances the relative density (from 72.4% to 92.9%), ionic conductivity (from 1.3×10−5 to 6.7×10−4S cm−1), mechanical strength (from 1.36 to 5.36 GPa) and air stability (anti-Li2CO3) of the electrolyte. Density functional theory (DFT) results reveal that the formation of Li3BO3 contributes to the improvement of the interfacial lithiophilicity, and the interface resistance is reduced from 1219 to 32 Ω cm-2. The critical current density (CCD) is enhanced from 0.1 to 0.7 mA cm-2, and the cells can be stably cycled for more than 1000 h at a current density of 0.2 mA cm-2 with a low overpotential at room temperature.