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Title: Transitions from near-surface to interior redox upon lithiation in conversion electrode materials

Nanoparticle electrodes in lithium-ion batteries have both near-surface and interior contributions to their redox capacity, each with distinct rate capabilities. Using combined electron microscopy, synchrotron X-ray methods and ab initio calculations, we have investigated the lithiation pathways that occur in NiO electrodes. We find that the near-surface electroactive (Ni²⁺→Ni⁰) sites saturated very quickly, and then encounter unexpected difficulty in propagating the phase transition into the electrode (referred to as a “shrinking-core” mode). However, the interior capacity for Ni²⁺→Ni⁰ can be accessed efficiently following the nucleation of lithiation “fingers” which propagate into the sample bulk, but only after a certain incubation time. Our microstructural observations of the transition from a slow shrinking-core mode to a faster lithiation finger mode corroborate with synchrotron characterization of large-format batteries, and can be rationalized by stress effects on transport at high-rate discharge. The finite incubation time of the lithiation fingers sets the intrinsic limitation for the rate capability (and thus the power) of NiO for electrochemical energy storage devices. The present work unravels the link between the nanoscale reaction pathways and the C-rate-dependent capacity loss, and provides guidance for the further design of battery materials that favors high C-rate charging.
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [4] ;  [5] ;  [6] ;  [6] ;  [7] ;  [1] ;  [1] ;  [2] ;  [8] ;  [4]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
  2. MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  4. Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States)
  5. Cornell Univ., Ithaca, NY (United States)
  6. Colorado School of Mines, Golden, CO (United States)
  7. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  8. Colorado School of Mines, Golden, CO (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
OSTI Identifier:
1182533
Report Number(s):
BNL--107622-2015-JA
Journal ID: ISSN 1530-6984; R&D Project: 16060; KC0403020
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 15; Journal Issue: 2; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
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 functional nanomaterials; lithium ion battery; nickel oxide; conversion reaction; in-situ TEM; incubation rate capability