Exploration of tetrahedral structures in silicate cathodes using a motif-network scheme

TL;DR

This study employs a motif-network search to explore and classify tetrahedral structures in A2MSiO4 silicate cathodes, revealing new structures and stability indicators, especially in less-studied Na systems.

Contribution

The paper introduces a motif-network scheme to identify and classify diverse tetrahedral structures in silicate cathodes, including novel motifs in Na-based systems.

Findings

Discovered new tetrahedral-network structures with different dimensional frameworks.

Identified stability trends and indicators for various A2MSiO4 systems.

Predicted ground state structures for Na-based silicate cathodes.

Abstract

Using a motif-network search scheme, we studied the tetrahedral structures of the dilithium/disodium transition metal orthosilicates A2MSiO4 with A = Li or Na and M = Mn, Fe or Co. In addition to finding all previously reported structures, we discovered many other different tetrahedral-network-based crystal structures which are highly degenerate in energy. These structures can be classified into structures with 1D, 2D and 3D M-Si-O frameworks. A clear trend of the structural preference in different systems was revealed and possible indicators that affect the structure stabilities were introduced. For the case of Na systems which have been much less investigated in the literature relative to the Li systems, we predicted their ground state structures and found evidence for the existence of new structural motifs.