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Visualizing the chemistry and structure dynamics in lithium-ion batteries by in-situ neutron diffraction.

Wang XL, An K, Cai L, Feng Z, Nagler SE, Daniel C, Rhodes KJ, Stoica AD, Skorpenske HD, Liang C, Zhang W, Kim J, Qi Y, Harris SJ - Sci Rep (2012)

Bottom Line: The succession of Li-Graphite intercalation phases was fully captured under an 1C charge-discharge condition (i.e., charge to full capacity in 1 hour).However, the lithiation and dilithiation pathways are distinctively different and, unlike in slowing charging experiments with which the Li-Graphite phase diagram was established, no LiC₂₄ phase was found during charge at 1C rate.Approximately 75 mol. % of the graphite converts to LiC₆ at full charge, and a lattice dilation as large as 4% was observed during a charge-discharge cycle.

View Article: PubMed Central - PubMed

Affiliation: Chemical and Engineering Materials Division, Oak Ridge National Laboratory Oak Ridge, TN 37831-6465, USA. xlwang@cityu.edu.hk

ABSTRACT
We report an in-situ neutron diffraction study of a large format pouch battery cell. The succession of Li-Graphite intercalation phases was fully captured under an 1C charge-discharge condition (i.e., charge to full capacity in 1 hour). However, the lithiation and dilithiation pathways are distinctively different and, unlike in slowing charging experiments with which the Li-Graphite phase diagram was established, no LiC₂₄ phase was found during charge at 1C rate. Approximately 75 mol. % of the graphite converts to LiC₆ at full charge, and a lattice dilation as large as 4% was observed during a charge-discharge cycle. Our work demonstrates the potential of in-situ, time and spatially resolved neutron diffraction study of the dynamic chemical and structural changes in "real-world" batteries under realistic cycling conditions, which should provide microscopic insights on degradation and the important role of diffusion kinetics in energy storage materials.

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Related in: MedlinePlus

(a) Neutron diffraction patterns obtained at charged (4.2 V) and discharged (2.7 V) conditions along with the results of Rietveld refinement.(b) In-situ neutron diffraction pattern during a charge and discharge cycle. The in-situ diffraction data, averaged over 7 cycles, are binned into 2.5 minutes histograms. The voltage (current) is plotted in the side panel to the left (right) of the diffraction data. The acronyms used in the figure are as follows: CVD-constant voltage discharge, CCD-constant current discharge, OCV open circuit voltage, CVC-constant voltage charge, and CPC-constant power charge.
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f2: (a) Neutron diffraction patterns obtained at charged (4.2 V) and discharged (2.7 V) conditions along with the results of Rietveld refinement.(b) In-situ neutron diffraction pattern during a charge and discharge cycle. The in-situ diffraction data, averaged over 7 cycles, are binned into 2.5 minutes histograms. The voltage (current) is plotted in the side panel to the left (right) of the diffraction data. The acronyms used in the figure are as follows: CVD-constant voltage discharge, CCD-constant current discharge, OCV open circuit voltage, CVC-constant voltage charge, and CPC-constant power charge.

Mentions: For precise phase analysis, neutron diffraction patterns at fully charged (4.2 V) and discharged (2.7 V) conditions were measured for ~1 hour of counting time. The results are shown in Figure 2(a), along with Rietveld refinements for each pattern. Four phases were observed in the fully discharged condition: NMC cathode and graphite anode, plus the Al and Cu current collectors. In the charged condition, most of the graphite phase had transformed to LiC6 and LiC12, with only traces of the graphite phase remaining. An additional peak was found at ~2.05 Å, which cannot be identified with any of the above phases, but it remained unchanged during charge and discharge.


Visualizing the chemistry and structure dynamics in lithium-ion batteries by in-situ neutron diffraction.

Wang XL, An K, Cai L, Feng Z, Nagler SE, Daniel C, Rhodes KJ, Stoica AD, Skorpenske HD, Liang C, Zhang W, Kim J, Qi Y, Harris SJ - Sci Rep (2012)

(a) Neutron diffraction patterns obtained at charged (4.2 V) and discharged (2.7 V) conditions along with the results of Rietveld refinement.(b) In-situ neutron diffraction pattern during a charge and discharge cycle. The in-situ diffraction data, averaged over 7 cycles, are binned into 2.5 minutes histograms. The voltage (current) is plotted in the side panel to the left (right) of the diffraction data. The acronyms used in the figure are as follows: CVD-constant voltage discharge, CCD-constant current discharge, OCV open circuit voltage, CVC-constant voltage charge, and CPC-constant power charge.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475991&req=5

f2: (a) Neutron diffraction patterns obtained at charged (4.2 V) and discharged (2.7 V) conditions along with the results of Rietveld refinement.(b) In-situ neutron diffraction pattern during a charge and discharge cycle. The in-situ diffraction data, averaged over 7 cycles, are binned into 2.5 minutes histograms. The voltage (current) is plotted in the side panel to the left (right) of the diffraction data. The acronyms used in the figure are as follows: CVD-constant voltage discharge, CCD-constant current discharge, OCV open circuit voltage, CVC-constant voltage charge, and CPC-constant power charge.
Mentions: For precise phase analysis, neutron diffraction patterns at fully charged (4.2 V) and discharged (2.7 V) conditions were measured for ~1 hour of counting time. The results are shown in Figure 2(a), along with Rietveld refinements for each pattern. Four phases were observed in the fully discharged condition: NMC cathode and graphite anode, plus the Al and Cu current collectors. In the charged condition, most of the graphite phase had transformed to LiC6 and LiC12, with only traces of the graphite phase remaining. An additional peak was found at ~2.05 Å, which cannot be identified with any of the above phases, but it remained unchanged during charge and discharge.

Bottom Line: The succession of Li-Graphite intercalation phases was fully captured under an 1C charge-discharge condition (i.e., charge to full capacity in 1 hour).However, the lithiation and dilithiation pathways are distinctively different and, unlike in slowing charging experiments with which the Li-Graphite phase diagram was established, no LiC₂₄ phase was found during charge at 1C rate.Approximately 75 mol. % of the graphite converts to LiC₆ at full charge, and a lattice dilation as large as 4% was observed during a charge-discharge cycle.

View Article: PubMed Central - PubMed

Affiliation: Chemical and Engineering Materials Division, Oak Ridge National Laboratory Oak Ridge, TN 37831-6465, USA. xlwang@cityu.edu.hk

ABSTRACT
We report an in-situ neutron diffraction study of a large format pouch battery cell. The succession of Li-Graphite intercalation phases was fully captured under an 1C charge-discharge condition (i.e., charge to full capacity in 1 hour). However, the lithiation and dilithiation pathways are distinctively different and, unlike in slowing charging experiments with which the Li-Graphite phase diagram was established, no LiC₂₄ phase was found during charge at 1C rate. Approximately 75 mol. % of the graphite converts to LiC₆ at full charge, and a lattice dilation as large as 4% was observed during a charge-discharge cycle. Our work demonstrates the potential of in-situ, time and spatially resolved neutron diffraction study of the dynamic chemical and structural changes in "real-world" batteries under realistic cycling conditions, which should provide microscopic insights on degradation and the important role of diffusion kinetics in energy storage materials.

Show MeSH
Related in: MedlinePlus