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This content will become publicly available on December 17, 2018

Title: Unveiling the Structural Evolution of Ag 1.2Mn 8O 16 under Coulombically Controlled (De)Lithiation

MnO 2 materials are considered promising cathode materials for rechargeable lithium, sodium, and magnesi-um batteries due to their earth abundance and environmental friendliness. One polymorph of MnO 2, α-MnO 2, has 2×2 tunnels (4.6 Å × 4.6 Å) in its structural framework, which provide facile diffusion pathways for guest ions. In this work, a silver ion containing α-MnO 2 (Ag 1.2Mn 8O 16) is examined as a candidate cathode material for Li based batteries. Electro-chemical stability of Ag 1.2Mn 8O 16 is investigated through Coulombically controlled reduction under 2 or 4 molar electron equivalents (e.e.). Terminal discharge voltage remains almost constant under 2 e.e. of cycling, whereas it continuously decreases under repetitive reduction by 4 e.e. Thus, detailed structural analyses were utilized to investigate the structural evolution upon lithiation. Significant increases in lattice a (17.7 %) and atomic distances (~4.8 %) are observed when x in Li xAg 1.2Mn 8O 16 is >4. Ag metal forms at this level of lithiation concomitant with a large structural distortion to the Mn-O framework. In contrast, lattice a only expands by 2.2 % and Mn-O/Mn-Mn distances show minor changes (~1.4 %) at x <2. The structural deformation (tunnel breakage) at x >4 inhibitsmore » the recovery of the original structure, leading to poor cycle stability at high lithiation levels. This report establishes the correlation among local structure changes, amorphization processes, formation of Ag 0 and long term cycle stability for this silver containing α-MnO 2 type material at both low and high lithiation levels.« less
Authors:
ORCiD logo [1] ;  [2] ;  [1] ;  [2] ;  [2] ; ORCiD logo [3] ; ORCiD logo [1] ;  [1]
  1. Stony Brook Univ., Stony Brook, NY (United States)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. Stony Brook Univ., Stony Brook, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-203551-2018-JAAM
Journal ID: ISSN 0897-4756
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 30; Journal Issue: 2; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE
OSTI Identifier:
1434772