First-Principles and Experimental Investigation of ABO4 Zircons as Calcium Intercalation Cathodes

Jiyoon Kim; Dogancan Sari; Qian Chen; Ann Rutt; Gerbrand Ceder; Kristin A Persson

doi:10.1021/acs.chemmater.4c00062

First-Principles and Experimental Investigation of ABO₄ Zircons as Calcium Intercalation Cathodes

Chem Mater. 2024 Apr 25;36(9):4444-4455. doi: 10.1021/acs.chemmater.4c00062. eCollection 2024 May 14.

Authors

Jiyoon Kim^{1

2}, Dogancan Sari^{1

2}, Qian Chen², Ann Rutt^{1

2}, Gerbrand Ceder^{1

2}, Kristin A Persson^{1

2

3}

Affiliations

¹ Department of Materials Science and Engineering, University of California, Berkeley, California 94704, United States.
² Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
³ Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.

Abstract

Identifying next-generation batteries with multivalent ions, such as Ca²⁺ is an active area of research to meet the increasing demand for large-scale, renewable energy storage solutions. Despite the promise of higher energy densities with multivalent batteries, one of their main challenges is addressing the sluggish kinetics in cathodes that arise from stronger electrostatic interactions between the multivalent ion and host lattice. In this paper, zircons are theoretically and experimentally evaluated as Ca cathodes. A migration barrier as low as 113 meV is computationally found in YVO₄, which is the lowest Ca²⁺ barrier reported to date. Low barriers are confirmed across 18 zircon compositions, which are related to the low coordination change and reduced interstitial site preference of Ca²⁺ along the diffusion pathway. Among the four materials (BiVO₄, YVO₄, EuCrO₄, and YCrO₄) that were synthesized, characterized, and electrochemically cycled, the highest initial capacity of 81 mA h/g and the most reversible capacity of 65 mA h/g were achieved in YVO₄ and BiVO₄, respectively. Despite the facile migration of multivalent ions in zircons, density functional theory predictions of the unstable, discharged structures at higher Ca²⁺ concentrations (Ca_x>0.25ABO₄), the low dimensionality of the migration pathway, and the defect analysis of the B site atom can rationalize the limited intercalation observed upon electrochemical cycling.