| Evaluation of high-entropy oxides as candidate anode materials for Li-ion cells Maciej Moździerz1; Juliusz Dąbrowa2; Konrad Swierczek3; 1AGH UNIVERSITY OF SCIENCE AND TECHNOLOGY, FACULTY OF ENERGY AND FUELS, Kraków, Poland; 2AGH UNIVERSITY OF SCIENCE AND TECHNOLOGY, FACULTY OF MATERIALS SCIENCE AND CERAMICS, Kraków, Poland; 3AGH UNIVERSITY OF SCIENCE AND TECHNOLOGY, FACULTY OF ENERGY AND FUELS, Krakow, Poland; PAPER: 188/AdvancedMaterials/Regular (Oral) SCHEDULED: 17:50/Tue. 29 Nov. 2022/Saitong ABSTRACT: Nowadays, Li-ion batteries are dominating electrical energy storage systems for portable electronics, and become widespread in the fast developing electric vehicles market. Their further development is also essential for the so-called large-scale energy storage, enabling effective balancing of power grid. Consequently, there is a growing worldwide demand for the next generation of Li-ion cells, having higher energy density, higher power, improved safety, and extended lifespan. Up to date, many novel alternative materials have been proposed as substitution for those currently used in the commercial Li-ion cells, which are usually based on lithium metal oxide cathodes and graphite anodes [1,2]. Among new candidate anode materials, those working on a basis of different reaction mechanisms with lithium have been proposed, including conversion-type and alloying-type reactivity, as compared with intercalation-based electrochemical reaction occurring for commonly used graphite. While high capacity could be obtained for various studied compositions, there are still many unresolved issues, with the main one including fast capacity fading during charge-discharge cycles [2]. Most recently it has been found that application of the novel group of compounds, the multi-component high-entropy oxides, allows significantly improving stability during cycling, which is thanks to synergistic effects [3]. In the literature there is an ongoing debate about electrochemical mechanisms occurring for the high-entropy electrodes, which have not been fully understood yet [3,4,5]. This work is focused on the exploration of the high-entropy oxides as anode materials in Li-ion cells. The presented studies were aimed on finding the correlation between chemical composition, crystal structure and electrochemical performance. Different, at least five-component oxides from Li-Co-Cu-Cr-Fe-Mn-Ni-Mg-Sn-Zn-O system were successfully synthesized, with their crystal structure characterized through X-ray diffraction method, to be cubic Fm-3m for MO, and Fd-3m for M<sub>3</sub>O<sub>4</sub> materials, respectively. Homogeneity of the compounds was confirmed with scanning electron microscopy, combined with elemental analysis. In order to test electrochemical performance in Li-ion batteries, galvanostatic charge/discharge, cyclic voltammetry and impedance spectroscopy techniques were used. Interesting results, with high and reversible capacity observed for both groups of the studied high-entropy oxides were obtained. For example, for (Co,Cr,Fe,Mn,Ni)<sub>3</sub>O<sub>4</sub>-based anode discharge capacity exceeding 400 mAhg<sup>-1</sup> was measured in the first 20 cycles. Based on operando structural investigations, the respective models of the electrochemical reactions could be postulated. The performed studies proved applicability of the high-entropy approach to design novel Li-ion anode materials having improved electrochemical characteristics. References: [1] S. Chu et al., Nat. Mater., vol. 16, no. 1, pp. 16–22, 2016. [2] K. Cao et al., Mater. Chem. Front., vol. 1, no. 11, pp. 2213–2242, 2017. [3] A. Sarkar et al., Nat. Commun., vol. 9, no. 1, 2018. [4] P. Ghigna et al., ACS Appl. Mater. Interfaces (2020), https://doi.org/10.1021/acsami.0c13161. [5] T.-Y. Chen et al., J. Mater. Chem. A. 8 (2020) 21756–21770. |
