Enhanced Li-Ion Diffusion and Cycling Stability of Ni-Free High-Entropy Spinel Oxide Anodes with High-Concentration Oxygen Vacancies

Bin Xiao; Gang Wu; Tongde Wang; Zhengang Wei; Zelin Xie; Yanwei Sui; Jiqiu Qi; Fuxiang Wei; Xiahui Zhang; Lin-Bo Tang; Jun-Chao Zheng

doi:10.1021/acsami.2c12374

Enhanced Li-Ion Diffusion and Cycling Stability of Ni-Free High-Entropy Spinel Oxide Anodes with High-Concentration Oxygen Vacancies

ACS Appl Mater Interfaces. 2023 Jan 18;15(2):2792-2803. doi: 10.1021/acsami.2c12374. Epub 2023 Jan 6.

Authors

Bin Xiao¹, Gang Wu¹, Tongde Wang¹, Zhengang Wei¹, Zelin Xie¹, Yanwei Sui¹, Jiqiu Qi¹, Fuxiang Wei¹, Xiahui Zhang², Lin-Bo Tang³, Jun-Chao Zheng³

Affiliations

¹ School of Materials Science and Physics, China University of Mining and Technology, Xuzhou221116, P. R. China.
² School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington99164, United States.
³ School of Metallurgy and Environment, Central South University, Changsha410083, P. R. China.

PMID: 36606677
DOI: 10.1021/acsami.2c12374

Abstract

High-entropy oxide (HEO) is an emerging type of anode material for lithium-ion batteries with excellent properties, where high-concentration oxygen vacancies can effectively enhance the diffusion coefficient of lithium ions. In this study, Ni-free spinel-type HEOs ((FeCoCrMnZn)₃O₄ and (FeCoCrMnMg)₃O₄) were prepared via ball milling, and the effects of zinc and magnesium on the concentration of oxygen vacancy (O_V), lithium-ion diffusion coefficient (D_Li⁺), and electrochemical performance of HEOs were investigated. Ab initio calculations show that the addition of zinc narrows down the band gap and thus improves the electrical conductivity. X-ray photoelectron spectroscopy (XPS) results show that (FeCoCrMnZn)₃O₄ (42.7%) and (FeCoCrMnMg)₃O₄ (42.5%) have high O_V concentration. During charge/discharge, the O_V concentration of (FeCoCrMnZn)₃O₄ is higher than that of (FeCoCrMnMg)₃O₄. The galvanostatic intermittent titration technique (GITT) results show that the D_Li⁺ value of (FeCoCrMnZn)₃O₄ is higher than that of (FeCoCrMnMg)₃O₄ during charge and discharge. All of that can improve its specific discharge capacity and enhance its cycle stability. (FeCoCrMnZn)₃O₄ achieved a discharge capacity of 828.6 mAh g^-1 at 2.0 A g^-1 after 2000 cycles. This work provides a deep understanding of the structure and performance of HEO.

Keywords: Li-ion diffusion coefficient; band-gap width; high-entropy spinel oxide; long-term cycling stability; oxygen vacancy concentration.