CAVD, towards better characterization of void space for ionic transport analysis

Abstract

Geometric crystal structure analysis using three-dimensional Voronoi tessellation provides intuitive insights into the ionic transport behavior of metal-ion electrode materials or solid electrolytes by mapping the void space in a framework onto a network. The existing tools typically consider only the local voids by mapping them with Voronoi polyhedra vertices and then define the mobile ions pathways using the Voronoi edges connecting these vertices. We show that in some structures mobile ions are located on Voronoi polyhedra faces and thus cannot be located by a standard approach. To address this deficiency, we extend the method to include Voronoi faces in the constructed network. This method has been implemented in the CAVD python package. Its effectiveness is demonstrated by 99% recovery rate for the lattice sites of mobile ions in 6,955 Li-, Na-, Mg- and Al-containing ionic compounds extracted from the Inorganic Crystal Structure Database. In addition, various quantitative descriptors of the network can be used to identify and rank the materials and further used in materials databases for machine learning.

Automatic Migration Path Exploration for Multivalent Battery Cathodes using Geometrical Descriptors

“…Structural and chemical descriptors describing the ion mobility in bulk structures have been discussed extensively in literature [10,11,29–31] . Three main contributions to the barrier obtained from DFT calculations have been identified to be (i) electrostatic interactions as well as (ii) electronic and (iii) ionic relaxation effects [13,32,33] .…”

High-throughput screening platform for solid electrolytes combining hierarchical ion-transport prediction algorithms

“…Since the upper threshold is not considered in this paper, it is set to 3 Å. At present, we have provided a reliable reference range of the threshold in our resent paper 35 . In the BVSE calculation, the valence state of mobile ion is usually same with that in the CIF file, and the grid resolution is set as 0.1 Å.…”

“…For hierarchical calculations, the screening value of CAVD presents the range of RLFS, it can reference the threshold in the paper 35 . The screening value of BVSE is set between 0-1.2 eV in one-dimensional migration paths.…”

“…The crystal space can be divided into two non-intersecting topological subspaces: the subspace of atoms and the subspace of interatomic interstices 21 . To characterize and analyze these two subspaces, we develop the crystal structural geometric analysis program CAVD 35 . In the CAVD calculation process, the interstitial network is first obtained from the subspace of atoms in the crystal structure by radical Voronoi decomposition 22 .…”

Benchmarking Coordination Number Prediction Algorithms on Inorganic Crystal Structures

“…Coordination numbers and geometries (e.g., tetrahedral, octahedral, trigonal planar) play a fundamental role in describing materials and dictating their properties. Some well-known examples throughout materials science include: (i) the local coordination of a site can predict the type of orbital interactions and crystal field splitting; (ii) the feasibility of hypothetical zeolites for catalysis, gas separation, or ion-exchange 1 is frequently assessed by the distortion of the tetrahedral SiO 4 building blocks; 2,3 (iii) in battery materials, diffusion path topologies can be classified using the coordination geometries of the diffusing ions; 4,5 (iv) the relative arrangement of octahedral Pb-halide motifs significantly influences the electronic properties of hybrid organic-inorganic halide perovskites. 6 The primary challenge is to determine which atoms in the crystal are connected or bonded to one another and which are not.…”