Extracting Physics from Database with Systematic DFT Calculations: Intercalation Energies of Layered Intercalation Compounds with Various Ions

Layered intercalation compounds, which have a structure in which atoms or molecules (intercalants) are inserted into the interlayer of a layered compound (host), have been extensively studied due to their characteristic physical properties and the variety of synthetic methods^[1]. Their applications in energy storage have been investigated due to their ability to intercalate/de-intercalate ions, and various properties resulting from their two-dimensional nature, such as superconductivity and topological electronic states, have also been studied. In this context, we have recently reported the possibility of new graphite intercalation compounds with superconductivity and charge density states.^[2] There are various combinations of intercalants and hosts in layered intercalation compounds, and it is important to control the combinations to achieve some functional development. However, a comprehensive understanding of which combinations of hosts and intercalants are stable has not been achieved.<br/>To achieve this, we performed systematic DFT calculations for 9,024 layered intercalation compounds with a structure in which a single atom is inserted into the host changing the intercalant atom, and constructed database of their optimized crystal structures, electronic states, and intercalation energies, which is the reaction energy between the host and the intercalant. Consequently, we revealed that the intercalation energy can be linearly regressed, using only two experimental value. The obtained equation was found to be similar to reported ones in crystalline solids with divalent metal ion^[3] and metal-ligand complex.^[4]<br/>This result develops material design criteria for layered intercalation compounds and has the potential to be applied to other inorganic compounds with different structures. The details will be shown in my presentation.<br/>This study was supported by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) (Grant no. 19H00818 and 19H05787), and the special fund (Tenkai) by the Institute of Industrial Science, the University of Tokyo.<br/><br/><b>References</b><br/>[1] M. Lapipan <i>et al.</i>, <i>Prog. Mater. Sci.</i> <b>109</b> (2020) 100631.<br/>[2] N. Kawaguchi <i>et al.</i>,<i> J. Phys. Chem. C</i> <b>127 </b>(2023) 9833-9843.<br/>[3] D. A. Sverjensky <i>et al.</i>, <i>Nature</i> <b>356</b> (1992) 231-234.<br/>[4] H. Xu <i>et al.</i>, <i>ACS Omega</i> <b>2</b> (2017) 7185-7193.