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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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(a) The crystal structure of LixNiyCozMn(1−y−z)O2 NMC cathode.The blue line indicates the unit cell. The Ni, Mn, and Co atoms are randomly distributed on M sites. (b) Change of lattice parameters and the unit-cell volume of the NMC cathode phase during a charge and discharge cycle.
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f4: (a) The crystal structure of LixNiyCozMn(1−y−z)O2 NMC cathode.The blue line indicates the unit cell. The Ni, Mn, and Co atoms are randomly distributed on M sites. (b) Change of lattice parameters and the unit-cell volume of the NMC cathode phase during a charge and discharge cycle.

Mentions: In-situ neutron diffraction patterns collected during cycling are presented in Figure 2(b). Continuous acquisition of neutron diffraction data was carried out using an event-mode data acquisition2930 system over the course of ~20 hours during which time the battery was cycled through 7 charge-discharge sequences. The data was binned into diffraction patterns corresponding to 2.5 minutes duration, and these were strobscopically averaged2526 over the 7 charge-discharge cycles. More details of event-based data acquisition and stroboscopic averaging are given in Supplemental Materials. Despite averaging over 7 cycles (i.e., 17.5 min in total counting time), the statistical quality of each data set was inadequate for full Rietveld refinement of the complex diffraction patterns. A possible reason for the inadequate data is that the 7 cycles, over which the data were averaged, may not be identical. A slight difference in the charge or discharge cycles can lead to blurring or degradation of the diffraction data. Nevertheless, it is possible to utilize strong characteristic diffraction peaks to highlight the structural evolution in the graphite anode and NMC cathode during the charge-discharge cycles. The results are shown in Figures 3–4.


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) The crystal structure of LixNiyCozMn(1−y−z)O2 NMC cathode.The blue line indicates the unit cell. The Ni, Mn, and Co atoms are randomly distributed on M sites. (b) Change of lattice parameters and the unit-cell volume of the NMC cathode phase during a charge and discharge cycle.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: (a) The crystal structure of LixNiyCozMn(1−y−z)O2 NMC cathode.The blue line indicates the unit cell. The Ni, Mn, and Co atoms are randomly distributed on M sites. (b) Change of lattice parameters and the unit-cell volume of the NMC cathode phase during a charge and discharge cycle.
Mentions: In-situ neutron diffraction patterns collected during cycling are presented in Figure 2(b). Continuous acquisition of neutron diffraction data was carried out using an event-mode data acquisition2930 system over the course of ~20 hours during which time the battery was cycled through 7 charge-discharge sequences. The data was binned into diffraction patterns corresponding to 2.5 minutes duration, and these were strobscopically averaged2526 over the 7 charge-discharge cycles. More details of event-based data acquisition and stroboscopic averaging are given in Supplemental Materials. Despite averaging over 7 cycles (i.e., 17.5 min in total counting time), the statistical quality of each data set was inadequate for full Rietveld refinement of the complex diffraction patterns. A possible reason for the inadequate data is that the 7 cycles, over which the data were averaged, may not be identical. A slight difference in the charge or discharge cycles can lead to blurring or degradation of the diffraction data. Nevertheless, it is possible to utilize strong characteristic diffraction peaks to highlight the structural evolution in the graphite anode and NMC cathode during the charge-discharge cycles. The results are shown in Figures 3–4.

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