Home
Resources
Publications
Understanding the conversion mechanism and performance of monodisperse FeF 2 nanocrystal cathodes

Understanding the conversion mechanism and performance of monodisperse FeF 2 nanocrystal cathodes

Albert W Xiao, Hyeon Jeong Lee, Isaac Capone, Alex Robertson, Tae-Ung Wi, Jack Fawdon, Samuel Wheeler, Hyun-Wook Lee, Nicole Grobert, Mauro Pasta

Nat Mater. 2020 Jun;19(6):644-654.

PMID: 32094491

Abstract:

The application of transition metal fluorides as energy-dense cathode materials for lithium ion batteries has been hindered by inadequate understanding of their electrochemical capabilities and limitations. Here, we present an ideal system for mechanistic study through the colloidal synthesis of single-crystalline, monodisperse iron(II) fluoride nanorods. Near theoretical capacity (570 mA h g-1) and extraordinary cycling stability (>90% capacity retention after 50 cycles at C/20) is achieved solely through the use of an ionic liquid electrolyte (1 m LiFSI/Pyr1,3FSI), which forms a stable solid electrolyte interphase and prevents the fusing of particles. This stability extends over 200 cycles at much higher rates (C/2) and temperatures (50 °C). High-resolution analytical transmission electron microscopy reveals intricate morphological features, lattice orientation relationships and oxidation state changes that comprehensively describe the conversion mechanism. Phase evolution, diffusion kinetics and cell failure are critically influenced by surface-specific reactions. The reversibility of the conversion reaction is governed by topotactic cation diffusion through an invariant lattice of fluoride anions and the nucleation of metallic particles on semicoherent interfaces. This new understanding is used to showcase the inherently high discharge rate capability of FeF2.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP7789288	Iron(II) fluoride		7789-28-8	Price

As a specialist in analytical chemical Products, Alfa Chemistry offers consumers a wealth of raw materials and a full range of technologies and services.

QUICK LINKS

HEADQUARTERS

Tel:

Fax:

Email: