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Title: In Situ Observation of Single-Phase Lithium Intercalation in Sub-25-nm Nanoparticles

Although a non-equilibrium single-phase reaction, with the absence of nucleation and growth of a second phase, is believed to be a key factor for high-rate performance of lithium-ion batteries, it is thermodynamically unfavorable and usually proceeds in electrode materials with small particle sizes (tens of nanometers). Unfortunately, the phase evolutions inside such small particles are often shrouded by the macroscopic inhomogeneous reactions of electrodes containing millions of particles, leading to intensive debate over the size-dependent microscopic reaction mechanisms. Here, we provide a generally applicable methodology based on in-situ electron diffraction study on a multi-particle system to track the lithiation pathways in individual nanoparticles, and unambiguously reveal that lithiation of anatase TiO 2, previously long believed to be biphasic, converts to a single-phase reaction when the particle size is below ~25 nm. Our results imply the prevalence of such a size-dependent transition in lithiation mechanism among intercalation compounds whose lithium miscibility gaps are associated with a prominent size effect, and therefore provide important guidelines for designing high-power electrodes, especially cathodes.
 [1] ;  [2] ;  [3] ;  [4] ;  [1]
  1. Univ. of Pittsburgh, PA (United States). Dept. of Mechanical Engineering and Materials Science
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Center for Integrated Nanotechnologies
  3. Zhejiang Univ., Hangzhou (China). School of Materials Science and Engineering
  4. Yanshan Univ., Qin Huang Dao, Hebei Province (China). Nano Energy Center, State Key Lab. of Metastable Materials Science and Technology
Publication Date:
Report Number(s):
Journal ID: ISSN 0935-9648; 646434; TRN: US1702855
Grant/Contract Number:
AC04-94AL85000; SC0001160; DESC0001160
Accepted Manuscript
Journal Name:
Advanced Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 26; Journal ID: ISSN 0935-9648
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; multiparticle systems; single-phase Li+ intercalation; size-dependent lithiation pathway
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1401791