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Abstract The application of machine learning models to predict material properties is determined by the availability of high-quality data. We present an expert-curated dataset of lithium ion conductors and associated lithium ion conductivities measured by a.c. impedance spectroscopy. This dataset has 820 entries collected from 214 sources; entries contain a chemical composition, an expert-assigned structural label, and ionic conductivity at a specific temperature (from 5 to 873 °C). There are 403 unique chemical compositions with an associated ionic conductivity near room temperature (15–35 °C). The materials contained in this dataset are placed in the context of compounds reported in the Inorganic Crystal Structure Database with unsupervised machine learning and the Element Movers Distance. This dataset is used to train a CrabNet-based classifier to estimate whether a chemical composition has high or low ionic conductivity. This classifier is a practical tool to aid experimentalists in prioritizing candidates for further investigation as lithium ion conductors.

Machine learning has the potential to significantly speed-up the discovery of new materials in synthetic materials chemistry. Here the authors combine unsupervised machine learning and crystal structure prediction to predict a novel quaternary lithium solid electrolyte that is then synthesized.

The syntheses and crystal structures of 2-[2-(propan-2-ylidene)hydrazinyl]-1,3-benzothiazol-3-ium 3-nitrobenzenesulfonate (C10H12N2S+·C6H4NO5S−), (I), 2-[2-(3-nitrobenzenesulfonyl)hydrazinyl]-1,3-benzothiazole (C13H10N4O4S2), (II) and 2-[2-(3-nitrobenzenesulfonyl)hydrazinyl]-1,3-benzothiazol-3-ium 3-nitrobenzenesulfonate (C13H11N4O4S2+·C6H4NO5S−), (III) are reported. Salt (I) arose from an unexpected reaction of 2-hydrazinylbenzothiazole with the acetone solvent in the presence of 3-nitrobenzenesulfonyl chloride, whereas (II) and (III) were recovered from the equivalent reaction carried out in methanol. The crystal of (I) features ion pairs linked by pairs of N—H...Os (s = sulfonate) hydrogen bonds; adjacent cations interact by way of short π–π stacking interactions between the thiazole rings [centroid–centroid separation = 3.4274 (18) Å]. In (II), which crystallizes with two neutral molecules in the asymmetric unit, the molecules are linked by N—H...N and N—H...On (n = nitro) hydrogen bonds to generate [\overline{1}1\overline{1}] chains, which are cross-linked by C—H...O and π–π stacking interactions. The crystal of (III) features centrosymmetric tetramers (two cations and two anions) linked by cooperative N—H...O hydrogen bonds; C—H...O and π–π interactions occur between tetramers.