Size-dependent kinetics during non-equilibrium lithiation of nano-sized zinc ferrite.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30626870.
- Also identified by DOI 10.1038/s41467-018-07831-5 and PMC identifier 6327060.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Spinel transition metal oxides (TMOs) have emerged as promising anode materials for lithium-ion batteries. It has been shown that reducing their particle size to nanoscale dimensions benefits overall electrochemical performance. Here, we use in situ transmission electron microscopy to probe the lithiation behavior of spinel ZnFe<sub>2</sub>O<sub>4</sub> as a function of particle size. We have found that ZnFe<sub>2</sub>O<sub>4</sub> undergoes an intercalation-to-conversion reaction sequence, with the initial intercalation process being size dependent. Larger ZnFe<sub>2</sub>O<sub>4</sub> particles (40 nm) follow a two-phase intercalation reaction. In contrast, a solid-solution transformation dominates the early stages of discharge when the particle size is about 6-9 nm. Using a thermodynamic analysis, we find that the size-dependent kinetics originate from the interfacial energy between the two phases. Furthermore, the conversion reaction in both large and small particles favors {111} planes and follows a core-shell reaction mode. These results elucidate the intrinsic mechanism that permits fast reaction kinetics in smaller nanoparticles.