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Title: Sodiation kinetics of metal oxide conversion electrodes: A comparative study with lithiation

The development of sodium ion batteries (NIBs) can provide an alternative to lithium ion batteries (LIBs) for sustainable, low-cost energy storage. However, due to the larger size and higher m/e ratio of the sodium ion compared to lithium, sodiation reactions of candidate electrodes are expected to differ in significant ways from the corresponding lithium ones. In this work, we investigated the sodiation mechanism of a typical transition metal-oxide, NiO, through a set of correlated techniques, including electrochemical and synchrotron studies, real-time electron microscopy observation, and ab initio molecular dynamics (MD) simulations. We found that a crystalline Na₂O reaction layer that was formed at the beginning of sodiation plays an important role in blocking the further transport of sodium ions. In addition, sodiation in NiO exhibits a “shrinking-core” mode that results from a layer-by-layer reaction, as identified by ab initio MD simulations. For lithiation, however, the formation of Li anti-site defects significantly distorts the local NiO lattice that facilitates Li insertion, thus enhancing the overall reaction rate. These observations delineate the mechanistic difference between sodiation and lithiation in metal-oxide conversion materials. More importantly, our findings identify the importance of understanding the role of reaction layers on the functioning of electrodes andmore » thus provide critical insights into further optimizing NIB materials through surface engineering.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [1] ;  [1] ;  [4] ;  [4] ;  [5] ;  [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Univ. of Maryland, College Park, MD (United States)
  4. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  5. Colorado School of Mines, Golden, CO (United States)
Publication Date:
OSTI Identifier:
1214101
Report Number(s):
BNL--108330-2015-JA
Journal ID: ISSN 1530-6984; KC0403020
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 15; Journal Issue: 9; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States). Center for Functional Nanomaterials.
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE sodiation; kinetics; nickel oxides; reaction pathways; conversion electrodes; Center for Functional Nanomaterials