Comprehensive Dopant Screening in Li7La3Zr2O12 Garnet Solid Electrolyte

Promising Li7La3Zr2O12 (LLZO) garnet electrolytes for solid Li batteries are highly sensitive to doping to modify performance. Herein, LLZO samples with 59 different elemental dopants are synthesized with substitutions on each of the 3 sites (177 total materials). Many potential dopants successfully integrate into the LLZO garnet crystal structure (either cubic or tetragonal), while doping on the optimum site predicted from either previous DFT calculations or the far cheaper bond valence calculations promotes the cubic phase. Room temperature ionic conductivities of up to 1.2 × 10−3 S cm−1 are achieved demonstrating the quality of materials made in high‐throughput here, and 36 different dopants yield a >10x improvement in conductivity over undoped LLZO. This opens up dramatically the playground for new garnet materials. Other important metrics for electrolytes are also screened systematically. Electronic conductivity is generally suppressed with doping, though certain dopants need to be avoided as they enhance the risk of dendrite formation. The electrochemical stability window of the doped LLZO samples is also screened carefully and shows tunability with certain dopants improving the high voltage stability while others help at low voltage. The results will therefore serve to guide rational codoping studies to combine the benefits of various dopants. Doping garnet solid electrolytes is well known to promote ionic conductivity. Here, 59 different dopants are found to impact all key intrinsic properties. Critical current densities are found to correlate strongly to low voltage stability, while electronic conductivity plays no discernible role. While defect energies do not predict the ability to dope, they do predict conversion to the cubic phase.