Accommodating High Transformation Strains in Battery Electrodes via the Formation of Nanoscale Intermediate Phases
Virtually all intercalation compounds exhibit significant changes in unit cell volume as the working ion concentration varies. Using synchrotron radiation powder X-ray diffraction (PXD) and pair distribution function (PDF) analysis, we discover a new strain-accommodation mechanism.
This article is co-authored by Dorthe Bomholdt Ravnsbæk and describes a very important aspect of strain in the performance of olivine cathode materials.
Virtually all intercalation compounds exhibit significant changes in unit cell volume as the working ion concentration varies. NaxFePO4 (0 < x < 1, NFP) olivine, of interest as a cathode for sodium-ion batteries, is a model for topotactic, high-strain systems as it exhibits one of the largest discontinuous volume changes (∼17% by volume) during its first-order transition between two otherwise isostructural phases. Using synchrotron radiation powder X-ray diffraction (PXD) and pair distribution function (PDF) analysis, we discover a new strain-accommodation mechanism wherein a third, amorphous phase forms to buffer the large lattice mismatch between primary phases. The amorphous phase has short-range order over ∼1nm domains that is characterized by a and b parameters matching one crystalline end-member phase and a c parameter matching the other, but is not detectable by powder diffraction alone. We suggest that this strain-accommodation mechanism may generally apply to systems with large transformation strains.
Accommodating High Transformation Strains in Battery Electrodes via the Formation of Nanoscale Intermediate Phases: Operando Investigation of Olivine NaFePO4
Kai Xiang†, Wenting Xing†, Dorthe B. Ravnsbæk†‡, Liang Hong∥, Ming Tang∥, Zheng Li†, Kamila M. Wiaderek⊥, Olaf J. Borkiewicz⊥, Karena W. Chapman⊥, Peter J. Chupas⊥, and Yet-Ming Chiang*†
† Department of Material Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
‡ Department of Physics, Chemistry and Pharmaci, University of Southern Denmark, Campusvej 55, 5320 Odense M, Denmark
∥ Department of Material Science and Nanoengineering, Rice University, 6100 Main Street, Houston, Texas 77005, United States
⊥ X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, United States
Nano Lett., Article ASAP
Publication Date (Web): February 21, 2017
Copyright © 2017 American Chemical Society
Jon Fold von Bülow
Jon Fold von Bülow recieved his Cand. Scient. in Nanoscience from University of Copenhagen in 2011 and is currently working with upscaling Li- and Na-ion battery materials to the 100+ kg scale for Haldor Topsøe A/S.
Jon's main interest lies in energy technologies for the future and he started working with fusion energy at Risø National Laboratory for Sustainable Energy. He has since developed a growing interest in technologies that are closer to potential industrial application. He is a highly dedicated academic as well as a very active professional and have initiated and participated in many different projects.
His studies within nanotechnological material science and affiliation with Risø National Laboratories has taken him to Germany, China and the US, where he has collaborated independently with several international research groups. He has so far succeeded in pushing two academic projects to industrial application, first with the Danish company Coloplast A/S and recently with a California-based battery start-up – an invention that is currently being US patented.
Jon has conducted most of his work on Li-batteries in the facilities of California NanoSystems Institute (CNSI) as a research scholar at UCSB-MIT-Caltech Institute for Collaborative Biotechnologies (ICB). The manganese based cathode materials he fabricated during this period were all tuned for high-power applications and covers synthesis of various manganese oxides from solution, molten and solid states.
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