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Title: Improved electrochemical performance of spinel LiMn1.5Ni0.5O4 through MgF2 nano-coating

In this paper, a spinel LiMn1.5Ni0.5O4 (LMNO) cathode material synthesized by a sol–gel method is modified by MgF2 nano-coating via a wet coating strategy. The results of X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) showed that the MgF2 nano-coating layers do not physically change the bulk structure of the pristine material. Compared with the pristine compound, the MgF2-coated LMNO electrodes display enhanced cycling stabilities. Particularly, the 5 wt% MgF2-coated LMNO demonstrates the best reversibility, with a capacity retention of 89.9% after 100 cycles, much higher than that of the pristine material, 69.3%. The dQ/dV analysis and apparent Li+ diffusion coefficient calculation prove that the kinetic properties are enhanced after MgF2 surface modification, which partly explains the improved electrochemical performances. Electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR) data confirm that the MgF2 coating layer helps in suppressing the fast growth of the solid electrolyte interface (SEI) film in repeated cycling, which effectively stabilizes the spinel structure. Finally and additionally, differential scanning calorimetry (DSC) tests show that the MgF2 nano-coating layer also helps in enhancing the thermal stability of the LMNO cathode.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [3]
  1. Henan Univ., Kaifeng (China). Key Lab. of Photovoltaic Materials of Henan Province. School of Physics and Electronics
  2. Henan Univ., Kaifeng (China). Key Lab. of Photovoltaic Materials of Henan Province. School of Physics and Electronics; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
  4. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics
Publication Date:
OSTI Identifier:
1324145
Grant/Contract Number:
AC05-00OR22725; 50902044; 2015AA034201; 201308410027
Type:
Accepted Manuscript
Journal Name:
Nanoscale
Additional Journal Information:
Journal Volume: 7; Journal Issue: 38; Journal ID: ISSN 2040-3364
Publisher:
Royal Society of Chemistry
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Henan Univ., Kaifeng (China)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Natural Science Foundation of China; 863 Program of China; China Scholarship Council
Contributing Orgs:
Chinese Academy of Sciences (CAS), Beijing (China)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE