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Title: Degradation mechanism of over-charged LiCoO 2/mesocarbon microbeads battery during shallow depth of discharge cycling

LiCoO 2/mesocarbon microbeads (MCMB) batteries are over-charged to different voltage (4.4 V, 4.5 V, 4.6 V, and 4.7 V, respectively) for ten times, and then are cycled 1000 times for shallow depth of discharge. The morphology, structure, and electrochemical performance of the electrode materials were studied in detail in order to identify the capacity fading mechanism of over-charged battery after long-term cycling. The cycling performances of LiCoO 2/MCMB batteries are gradually aggravated with the increase of over-charging voltage and the degradation mechanism is diverse upon the degree of over-charging. Furthermore, the capacity fading after long-term cycling of battery over-charged to 4.6 V or 4.7 V is mainly attributed to the cathodes. Soft X-ray absorption spectroscopy (XAS) demonstrates that the lower valence state of cobalt exists on the surface of the LiCoO 2 after serious over-charging (4.6 V or 4.7 V), and cobalt is dissolved then deposited on the anode according to the result of energy dispersive spectrometry (EDS). But, after shallow over-charging (4.4 V or 4.5 V), the capacity deterioration is proposed as the loss of active lithium, presented by the generation of the SEI film on the anode, which is verified by water washed tests.
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  1. Harbin Inst. of Technology (China). MIIT Key Lab. of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; 2012AA110203; 51202047
Accepted Manuscript
Journal Name:
Journal of Power Sources
Additional Journal Information:
Journal Volume: 329; Journal Issue: C; Journal ID: ISSN 0378-7753
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
25 ENERGY STORAGE; 36 MATERIALS SCIENCE; LiCoO2/MCMB battery; Over-charging; Capacity fading mechanism; Long-term cycling; Lithium dendrites; Reduction and dissolution of cobalt
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1398547