H$_2$O and CO$_2$ Surface Contamination of the Lithium-Stuffed Garnet

Yuheng Li; Asmee M. Prabhu; Tej S. Choksi; Pieremanuele Canepa

doi:10.1039/D1TA10228A

paper

H $_{2}$ O and CO $_{2}$ Surface Contamination of the Lithium-Stuffed Garnet

arXiv:2201.09348 · doi:10.1039/D1TA10228A

Abstract

Understanding the reactivity of ubiquitous molecules on complex oxides has broad impacts in energy applications and catalysis. The garnet-type Li $_{7}$ La $_{3}$ Zr $_{2}$ O $_{12}$ is a promising solid-state electrolyte for lithium(Li)-ion batteries, and it readily reacts with H $_{2}$ O and CO $_{2}$ when exposed to ambient air. Such reactions form a contamination layer on Li $_{7}$ La $_{3}$ Zr $_{2}$ O $_{12}$ that is detrimental to the battery operations. The strong interactions of Li $_{7}$ La $_{3}$ Zr $_{2}$ O $_{12}$ with H $_{2}$ O and CO $_{2}$ , however, make Li $_{7}$ La $_{3}$ Zr $_{2}$ O $_{12}$ a promising support to catalyze H $_{2}$ O dissociation and CO $_{2}$ adsorption. Here, using first-principles calculations, we investigate the adsorption and reactions of H $_{2}$ O and CO $_{2}$ on a Li $_{7}$ La $_{3}$ Zr $_{2}$ O $_{12}$ surface. We show that H $_{2}$ O reacts through the exchange of proton and Li $^{+}$ and produces metal hydroxide species. At high H $_{2}$ O coverage, half of the H $_{2}$ O molecules dissociate while the other half remain intact. CO $_{2}$ reacts with the Li $_{7}$ La $_{3}$ Zr $_{2}$ O $_{12}$ surface directly to produce carbonate species. We clarify that the individual reactions of H $_{2}$ O and CO $_{2}$ with Li $_{7}$ La $_{3}$ Zr $_{2}$ O $_{12}$ are more thermodynamically favorable than the co-adsorption of H $_{2}$ O and CO $_{2}$ . Finally, we demonstrate that low temperature and high partial pressure promote the reactions of H $_{2}$ O and CO $_{2}$ with Li $_{7}$ La $_{3}$ Zr $_{2}$ O $_{12}$ . For energy storage application of Li $_{7}$ La $_{3}$ Zr $_{2}$ O $_{12}$ , our study guides processing conditions to minimize surface contamination. From a catalysis point of view, our findings reveal the potential of using complex oxides, such as Li $_{7}$ La $_{3}$ Zr $_{2}$ O $_{12}$ as a support for reactions requiring H $_{2}$ O dissociation and strong CO $_{2}$ adsorption.

H2​O and CO2​ Surface Contamination of the Lithium-Stuffed Garnet

Abstract

H $_{2}$ O and CO $_{2}$ Surface Contamination of the Lithium-Stuffed Garnet