Atomic Structure of 2 nm Size Metallic Cobalt Prepared by Electrochemical Conversion: An in Situ Pair Distribution Function Study

Wei Li (1) , Olaf Borkiewicz (2) , Matthieu Saubanère (3, 4) , Marie-Liesse Doublet (4) , Delphine Flahaut (5) , Peter Chupas (6) , Karena W Chapman (2) , Damien Dambournet (1)

1 PHENIX - PHysicochimie des Electrolytes et Nanosystèmes InterfaciauX
2 XSD - X-ray Science Division
3 RS2E - Réseau sur le stockage électrochimique de l'énergie
4 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
5 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux
6 ANL - Argonne National Laboratory [Lemont]

Conversion reactions, offering high capacity in batteries, imply a restructuration of the pristine atomic structure down to the nanoscale. The associated large broadening in the Bragg peaks of the restructured electrode renders the description of atomic structure, almost impossible using conventional X-ray diffraction. On the other hand, atomic pair distribution function (PDF) is well suited to probe the structure of few nanometer-sized particles. Here, we investigated the formation mechanism and structure of 2 nm particle size of metallic Co obtained by electrochemical conversion of CoF2. We found that the conversion process stabilized a disordered structure consisting of a hexagonal-close-pack-face-centered-pack intergrowth. The reaction was followed by in situ PDF, providing unique insight into the growth of highly defective Co nanoparticles.

Mots clés: Atoms; Cobalt; Particle size

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Wei Li, Olaf Borkiewicz, Matthieu Saubanère, Marie-Liesse Doublet, Delphine Flahaut, et al.. Atomic Structure of 2 nm Size Metallic Cobalt Prepared by Electrochemical Conversion: An in Situ Pair Distribution Function Study. Journal of Physical Chemistry C, 2018, 122 (42), pp.23861-23866. ⟨10.1021/acs.jpcc.8b06573⟩. ⟨hal-01900257⟩