ZnFe$_2$O$_4$ and ZnO/Fe$_2$O$_3$ nanoparticles as anode materials for lithium-ion batteries: understanding of the lithium storage mechanism

International audienceWith the depletion of fossil fuels and the growing environmental concerns, lithium-ion batteries received considerable attention to contribute to the development of electric vehicles and storage for renewable energies. However, existing lithium-ion batteries cannot reach sufficient energy density to address the needs for such applications. One of the issues limiting the energy density is the low specific capacity of the graphite anode (372 mAh/g). Mixed-transition metal oxides with a spinel structure (AB$_2$O$_4$ – A, B transition metals) appear as a promising solution to replace graphite with a higher theoretical capacity (between 750 and 1000 mAh/g). Among various oxides, ZnFe$_2$O$_4$ is an interesting substitute for graphite, as an abundant, cheap, non-toxic and environmental-friendly material with a high theoretical capacity (1000 mAh/g). The nanostructuration of this material as well as a carbon coating around the particles can also help to maintain a mechanical stability during cycling and enhance the lithium kinetics