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Title: Tunnel Structured α-MnO 2 with Different Tunnel Cations (H + , K + , Ag + ) as Cathode Materials in Rechargeable Lithium Batteries: The Role of Tunnel Cation on Electrochemistry

α-MnO 2 type manganese dioxide is an interesting prospective cathode material for reversible lithium insertion owing to its cation accessible tunnels (0.46nm x 0.46nm), high voltage, and low cost. The tunneled structure is synthetically formed by the assistance of cations acting as structure directing agents where the cations may remain in the tunnel. The electrochemistry of this family of materials is strongly dependent on the morphological and physicochemical (i.e. surface area, crystallite size, and average manganese oxidation state) properties as well as tunnel occupancy. For this work, we prepared a set of materials Mn 8O 16·0.81H 2O, K 0.81Mn 8O 16·0.78H 2O and Ag 1.33Mn 8O 16·0.95H 2O with similar nanorod morphology, crystallite size, surface area, and tunnel water content. This set of samples allowed us to investigate the role of tunnel cations in the electrochemistry of α-MnO 2 type manganese dioxide in a lithium based environment while minimizing the effects of the other parameters. The electrochemistry was evaluated using cyclic voltammetry, galvanostatic cycling, rate capability, and galvanostatic intermittent titration type testing. Mn 8O 16·0.81H 2O showed higher loaded voltages, improved capacity retention, and higher specific energy relative to K 0.81Mn 8O 16·0.78H 2O and Ag 1.33Mn 8O 16·0.95H 2O.more » After 100 cycles, Mn 8O 16·0.81H 2O delivered ~200% more capacity than Ag 1.33Mn 8O 16·0.95H 2O (64 vs. 129 mAh/g) and ~35% more capacity than K 0.81Mn 8O 16·0.78H 2O (85 vs. 129 mAh/g). Mn 8O 16·0.81H 2O also showed higher effective lithium diffusion coefficients (DLi+) and higher rate capability compared to K 0.81Mn 8O 16·0.78H 2O and Ag 1.33Mn 8O 16·0.95H 2O suggesting faster Li+ ion diffusion in the absence of large metal tunnel cations.« less
Authors:
 [1] ; ORCiD logo [2] ;  [3] ;  [1] ;  [4] ;  [1] ;  [5] ;  [5] ;  [6]
  1. Brookhaven National Laboratory (BNL), Upton, NY (United States). Energy Sciences Directorate
  2. Stony Brook Univ., NY (United States). Dept. of Chemistry
  3. Brookhaven National Laboratory (BNL), Upton, NY (United States). Energy Sciences Directorate; Tsinghua Univ., Beijing (China). Dept. of Materials Science and Engineering
  4. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
  5. Stony Brook Univ., NY (United States). Dept. of Chemistry and Dept. of Materials Science and Engineering
  6. Brookhaven National Laboratory (BNL), Upton, NY (United States). Energy Sciences Directorate; Stony Brook Univ., NY (United States). Dept. of Chemistry and Dept. of Materials Science and Engineering
Publication Date:
Report Number(s):
BNL-203332-2018-JAAM
Journal ID: ISSN 0013-4651
Grant/Contract Number:
SC0012704; SC0012673; AC02-98CH10886
Type:
Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 164; Journal Issue: 9; Journal ID: ISSN 0013-4651
Publisher:
The Electrochemical Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; Rechargeable; Li Battery; Cryptomelane; Hollandite; Manganese Dioxide; tunnel; cation; battery; energy storage; hollandite
OSTI Identifier:
1426450