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Title: Utilizing Co 2+/Co 3+ Redox Couple in P2-Layered Na 0.66Co 0.22Mn 0.44Ti 0.34O 2 Cathode for Sodium-Ion Batteries

Developing sodium-ion batteries for large-scale energy storage applications is facing big challenges of the lack of high-performance cathode materials. Here, a series of new cathode materials Na 0.66Co xMn 0.66–xTi 0.34O 2 for sodium-ion batteries are designed and synthesized aiming to reduce transition metal-ion ordering, charge ordering, as well as Na+ and vacancy ordering. An interesting structure change of Na 0.66Co xMn 0.66–xTi 0.34O 2 from orthorhombic to hexagonal is revealed when Co content increases from x = 0 to 0.33. In particular, Na 0.66Co 0.22Mn 0.44Ti 0.34O 2 with a P2-type layered structure delivers a reversible capacity of 120 mAh g -1 at 0.1 C. When the current density increases to 10 C, a reversible capacity of 63.2 mAh g -1 can still be obtained, indicating a promising rate capability. The low valence Co 2+ substitution results in the formation of average Mn 3.7+ valence state in Na 0.66Co 0.22Mn 0.44Ti 0.34O 2, effectively suppressing the Mn3+-induced Jahn–Teller distortion, and in turn stabilizing the layered structure. X-ray absorption spectroscopy results suggest that the charge compensation of Na 0.66Co 0.22Mn 0.44Ti 0.34O 2 during charge/discharge is contributed by Co 2.2+/Co 3+ and Mn 3.3+/Mn 4+ redox couples. This is themore » first time that the highly reversible Co 2+/Co 3+ redox couple is observed in P2-layered cathodes for sodium-ion batteries. This finding may open new approaches to design advanced intercalation-type cathode materials.« less
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3] ;  [1] ;  [2] ;  [2] ;  [1]
  1. Fudan Univ., Shanghai (China). Department of Materials Science
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Chemistry Division
  3. Fudan Univ., Shanghai (China). Department of Chemistry & Laser Chemistry Institute
Publication Date:
Report Number(s):
BNL-114116-2017-JA
Journal ID: ISSN 2198-3844; R&D Project: MA453MAEA
Grant/Contract Number:
SC0012704; AC02-06CH11357
Type:
Published Article
Journal Name:
Advanced Science
Additional Journal Information:
Journal Volume: 4; Journal Issue: 11; Journal ID: ISSN 2198-3844
Publisher:
Wiley
Research Org:
Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; 36 MATERIALS SCIENCE; National Synchrotron Light Source
OSTI Identifier:
1368103
Alternate Identifier(s):
OSTI ID: 1368104; OSTI ID: 1376159