DOI: 10.11583/dtu.27202446.v1
title: Sodium ion polyanionic cathode material dataset

description: We have created a database that includes both static and dynamic structures of four sodium ion polyanionic cathode materials NaMPO<sub>4</sub>(olivine) ,NaMPO<sub>4</sub>(maricite), Na<sub>2</sub>MSiO<sub>4</sub> and Na<sub>2.56</sub>M<sub>1.72</sub>(SO<sub>4</sub>)<sub>3</sub> , along with various structures incorporating doping of transition metal ions (M). We consider four different transition metal ions (Fe, Mn, Co, Ni). Sampling was done using structure optimization, ab-initio molecular dynamics and machine learning driven dynamical sampling. The dataset consist of 113,703 structures.For each sampled structure, we record its crystal composition, total energy, atom-wise force vectors, atom-wise magnetic moments, and point charges obtained through Bader analysis. Our polyanionic Sodium ion battery database serves as a valuable addition to existing datasets, enabling the exploration of phase space while providing insights into the dynamic behavior of the materials.For the sampling density functional theory (DFT) calculation were performed using the Vienna Ab initio simulation package (VASP) version 6.4. The Perdew-Burke-Ernzerhof (PBE) functional with Hubbard-U corrections were appliedwas utilized for all calculations. The U-values are similar to the ones used for materials project (Fe: 5.3eV, Mn: 3.9eV, Co: 3.32eV, Ni: 6.2eV). For all calculations, an energy cutoff of 520eV was applied, with a smearing width of 0.01eV and convergence criteria set to 1e-5eV for energy and 0.03eV/Å for forces. All calculations were performed with spin polarization. The k-points employed for the four materials were fixed, with NaMPO<sub>4</sub>(olivine) and NaMPO<sub>4</sub>(maricite) utilizing [3,4,6] gamma points, Na<sub>2</sub>MSiO<sub>4 </sub>employing [3,4,4] gamma points and Na<sub>2.56</sub>M<sub>1.72</sub>(SO<sub>4</sub>)<sub>3</sub> utilizing [2,3,4] gamma points. When constructing supercells, the gamma point in the direction of cell enlargement was halved.<br>The dataset, presented in XYZ format, along with a few Python scripts. The dataset is divided into single transition metal ions structures and multiple transition metal ion structures.This division is provided for each of the four cathode materials: NaMPO<sub>4</sub>(olivine) ,NaMPO<sub>4</sub>(maricite), Na<sub>2</sub>MSiO<sub>4</sub> and Na<sub>2.56</sub>M<sub>1.72</sub>(SO<sub>4</sub>)<sub>3</sub> . For example, Na<sub>2.56</sub>M<sub>1.72</sub>(SO<sub>4</sub>)<sub>3</sub> structures are split into single transition metal ion types<i> Na2M2SO4_alluadite_single.xyz </i>and multiple transition metal ion types <i>Na2M2SO4_alluadite_multiple.xyz. T</i>he combined dataset, consisting of 113,703 structures, is available in <i>Combined.xyz.</i><br>To extract structural compositions and physical properties, the ase.io.read function from ASE version 3.23.0 is used. An example of how to extract data and plot the physical properties is provided in https://github.com/dtu-energy/cathode-generation-workflow/tree/main/extract_data/read_data.py and https://github.com/dtu-energy/cathode-generation-workflow/tree/main/extract_data/utils.py contains two functions, one used to attached Bader charges to an ASE atom object an another to combine multiple XYZ data files.<br>To cite the data please use the doi https://doi.org/10.11583/DTU.27202446<br>