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Title: Understanding the Origins of Higher Capacities at Faster Rates in Lithium-Excess Li xNi 2–4x/3Sb x/3O 2

Here, the lithium-excess Li xNi 2-4x/3Sb x/3O 2 (LNSO) materials were previously shown to demonstrate higher capacities and improved cyclability with increasing lithium content. While the performance trend is promising, observed capacities are much lower than theoretical capacities, pointing to a need for further understanding of active redox processes in these materials. In this work, we study the electrochemical behavior of the LNSO materials as a function of lithium content and at slow and fast rates. Surprisingly, Li 1.15Ni 0.47Sb 0.38O 2 (LNSO-15) exhibits higher discharge capacities at faster rates and traverses distinct voltage curves at slow and fast rates. To understand these two peculiarities, we characterize the redox activity of nickel, antimony, and oxygen at different rates. While experiments confirm some nickel redox activity and oxygen loss, these two mechanisms cannot account for all observed capacity. We propose that the balance of the observed capacity may be due reversible oxygen redox and that the rate-dependent voltage curve features may derive from irreversible nickel migration occurring on slow charge. As future high energy density cathodes are likely to contain both lithium excess and high nickel content, both of these findings have important implications for the development of novel high capacitymore » cathode materials.« less
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [2] ;  [7]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Technische Univ. Munchen, Garching (Germany)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
  4. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
  5. Harvard Univ., Cambridge, MA (United States)
  6. Georgia Inst. of Technology, Atlanta, GA (United States)
  7. Univ. of California, Berkeley, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 6; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1374886