This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
Article http://pubs.acs.org/journal/acsodf
Atomic Layer Deposition of Al−W−Fluoride on LiCoO2 Cathodes: Comparison of Particle- and Electrode-Level Coatings Joong Sun Park,† Anil U. Mane,‡ Jeffrey W. Elam,*,‡ and Jason R. Croy*,† †
Chemical Sciences and Engineering Division and ‡Energy Systems Division, Argonne National Laboratory, Argonne, Illinois 60439, United States S Supporting Information *
ABSTRACT: Atomic layer deposition (ALD) of the well-known Al2O3 on a LiCoO2 system is compared with that of a newly developed AlWxFy material. ALD coatings (∼1 nm thick) of both materials are shown to be effective in improving cycle life through mitigation of surface-induced capacity losses. However, the behaviors of Al2O3 and AlWxFy are shown to be significantly different when coated directly on cathode particles versus deposition on a composite electrode composed of active materials, carbons, and binders. Electrochemical impedance spectroscopy, galvanostatic intermittent titration techniques, and four-point measurements suggest that electron transport is more limited in LiCoO2 particles coated with Al2O3 compared with that in particles coated with AlWxFy. The results show that proper design/choice of coating materials (e.g., AlWxFy) can improve capacity retention without sacrificing electron transport and suggest new avenues for engineering electrode−electrolyte interfaces to enable high-voltage operation of lithium-ion batteries.
■
and performance of lithium-ion cells.7,8,11,12 Coating directly on active materials, in general, allows scale-up (gram to kilograms) and easy implementation into current battery manufacturing processes.13 In addition, processing of active materials can be extended to various coating materials that require high deposition temperatures (>250−300 °C) such as some fluorides and sulfides because the crystallinity and morphologies of active materials are not affected by the typical temperatures used. On the contrary, ALD processing of electrodes inherently limits the choice to lower temperature coating materials (
