Annotation

Nowadays lithium-ion batteries (LIBs) are widely used, because they demonstrate the highest values of specific capacity and energy, and also have a long lifetime. To improve battery properties, new types of electrode materials are being developed to increase capacity and service life while maintaining market value. At the moment, graphite is used as an anode for LIBs, but its capacity (372 mAh/g) is moderate and, in addition, a noticeable decrease is observed during long-term cycling. Thus, it is an important task to develop new types of anode materials with high gravimetric capacity as well as improved stability during cycling process.

Among promising environmentally friendly, unexpensive materials, zinc ferrite ZnFe2O4 can be distinguished due to such unique properties as chemical and thermal stability and reduced toxicity of zinc compared to other metals. ZnFe2O4 belongs to the anode materials with the so-called hybrid mechanism, that is, after the main conversion reaction, the reaction between lithium and zinc proceeds to form an alloy. In this case, up to 9 electrons are transferred during the overall electrochemical process, resulting in a high theoretical capacity (up to 1000 mAh/g). The anode material with so high capacity will significantly reduce the mass of the final battery while maintaining its characteristics. However, ferrite-based electrode materials are not commercially available due to a number of problems with ZnFe2O4, including a rapid capacity` drop and low efficiency at high currents due to low conductivity, significant agglomeration, and large volume changes during lithiation/delithiation.

This project aims to overcome the poor performance of existing anode materials based on ZnFe2O4 for lithium-ion batteries. It is assumed that the conductivity of the crystal structure of ZnFe2O4 with oxygen vacancies will increase, and it can be assumed that the electrochemical performance of the material based on such a structure will become higher. Therefore, during the project realization, it is planned for the first time to establish the effect of oxygen vacancies and other defects in the structure of ZnFe2O4 on the electrochemical properties (specific capacity, power, stability during charge-discharge) in LIBs.

Expected results

In case of successful project realization, it will be pefrormed synthesis of ZnFe2O4 (ZFO) with defective structure (a given number of defects – oxygen vacancies by varying the synthesis methods), characterization of the obtained particles and testing of electrode materials based on them in the composition of a lithium-ion battery, as well as the identification of structural factors, affecting conductivity, electrochemical properties (capacity, stability during charge-discharge). The conductivity is expected to be higher for ZFO with oxygen vacancies than ZFO without/or with fewer amount of oxygen vacancies. Presumably, if the structure of the ZFO material with oxygen vacancies is reversibly transformed during charge-discharge, then by improving the conductivity of the spinel in common, it can be expected that ZFO with oxygen vacancies will work better at high currents, i.e. give higher capacity. The results of the project will provide an understanding of the basic functioning of ZFO with a defective structure in commercial electrolytes for LIBs composition of 1 M LiPF6 EC:DEC (DMC).

The electrochemical properties of electrode materials based on ZFO with oxygen vacancies and with a normal structure will be investigated. Compounds were analyzed in the course of oxidation and reduction (ex situ XRD, XPS, SEM and EDX). Successful fulfillment of the tasks of obtaining new types of anode materials for LIBs, set in the project, will attract interest from industry and society due to the high interest in the development of environmentally friendly materials for LIBs.

As a result of the project, at least four publications are expected to be published in scientific journals of the Q1 and Q2 quartiles, indexed by the Scopus and Web of Science, RSCI systems. The project at RSCF website

Publications

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