Issue 8, 2023

Impact of O3/P3 phase transition on the performance of the NaxTi1/6Mn1/6Fe1/6Co1/6Ni1/6Cu1/6O2 cathode material for Na-ion batteries

Abstract

The results of research on the structural, transport and electrochemical properties of the NaxTi1/6Mn1/6Fe1/6Co1/6Ni1/6Cu1/6O2 high entropy oxide cathode material for Na-ion batteries are presented. Pristine high entropy oxide (HEO) O3–NaTi1/6Mn1/6Fe1/6Co1/6Ni1/6Cu1/6O2 exhibits semiconducting behaviour and shows only one reversible O3/P3 phase transition. Electrochemical tests carried out in the voltage range of 1.5–3.9 V indicate a high decrease in capacity. Additional electrochemical tests performed for the limited voltage range of 3.2–3.9 V, for which only the P3 phase is present, show very high cycling stability. Experimental findings are discussed in view of electronic structure calculations performed using the KKR-CPA method in order to account for different models of chemical disorder in O3 and P3 phases of the NaTi1/6Mn1/6Fe1/6Co1/6Ni1/6Cu1/6O2 system. It was determined that specific atomic ordering of transition metal atoms in the O3 phase may lead to a semiconducting state, while a fully random distribution of these atoms tends to result in a metallic-like one. Conversely, a finite density of states was systematically found in the case of the P3 phase, irrespective of the considered model of transition metal atom arrangement. Hence, the extra ordering of transition metals in the O3 phase is a possible explanation for its poor transport properties, whereas the much better transport properties of the P3 phase are reflected in the very high efficiency during the cycling of the battery in the limited voltage range. Furthermore, XAS total electron yield (TEY) measurements showed that only manganese, cobalt and nickel are electrochemically active during charging and discharging of the battery in the 1.5–3.9 V range and that Co is the most effective element in the charge compensation mechanism of the NaxTi1/6Mn1/6Fe1/6Co1/6Ni1/6Cu1/6O2 oxide.

Graphical abstract: Impact of O3/P3 phase transition on the performance of the NaxTi1/6Mn1/6Fe1/6Co1/6Ni1/6Cu1/6O2 cathode material for Na-ion batteries

Supplementary files

Article information

Article type
Paper
Submitted
28 Oct 2022
Accepted
18 Jan 2023
First published
23 Jan 2023

J. Mater. Chem. A, 2023,11, 4248-4260

Impact of O3/P3 phase transition on the performance of the NaxTi1/6Mn1/6Fe1/6Co1/6Ni1/6Cu1/6O2 cathode material for Na-ion batteries

J. Molenda, A. Milewska, W. Zając, K. Walczak, M. Wolczko, A. Komenda and J. Tobola, J. Mater. Chem. A, 2023, 11, 4248 DOI: 10.1039/D2TA08431G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements