Size-dependent kinetics during non-equilibrium lithiation of nano-sized zinc ferrite

• Published in: Nature communications Vol. 10; no. 1; p. 93
• Main Authors: Li, Jing, Meng, Qingping, Zhang, Yiman, Peng, Lele, Yu, Guihua, Marschilok, Amy C., Wu, Lijun, Su, Dong, Takeuchi, Kenneth J., Takeuchi, Esther S., Zhu, Yimei, Stach, Eric A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 09.01.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 147/28; 639/301; 639/4077; 639/925; Anodes; Batteries; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Conversion; Electrochemical analysis; Electrochemistry; Electrode materials; Humanities and Social Sciences; Intercalation; Interfacial energy; Kinetics; Lithium; Lithium-ion batteries; multidisciplinary; Nanoparticles; Oxides; Particle size; Reaction kinetics; Rechargeable batteries; Science; Science (multidisciplinary); Spinel; Transition metal oxides; Transition metals; Transmission electron microscopy; Zinc; Zinc ferrites
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-07831-5

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 2 O 4 as a function of particle size. We have found that ZnFe 2 O 4 undergoes an intercalation-to-conversion reaction sequence, with the initial intercalation process being size dependent. Larger ZnFe 2 O 4 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. Reducing particle size of electrode materials to nanoscale dimensions is believed responsible for their enhanced reaction kinetics and electrochemical performance. Here, the authors use in situ transmission electron microscopy to study the dynamic process of the spinel zinc ferrite nanoparticles as a function of size, finding that the intercalation reaction pathway changes below a critical particle size.