Investigation of particle isolation in Li-ion battery electrodes using 7Li NMR spectroscopy

Kerlau, Marie; Reimer, Jeffrey A.; Cairns, Elton J.

doi:10.1016/j.elecom.2005.09.003

Cited by 29 publications

(64 citation statements)

References 17 publications

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“…However, the electrode materials used in ion-intercalation batteries undergo significant composition changes-which correlate to high storage capacity-that can induce structural changes and mechanical stresses; these changes can degrade battery performance metrics such as power, achievable storage capacity, and lifetime. [1][2][3][4][5][6][7][8] Microstructural damage has been observed directly in numerous electrode materials subjected to electrochemical cycling, both within single crystals (or grains) and among polycrystalline aggregates. 4,5,[7][8][9][10][11][12][13][14][15] While the relationships among electrode microstructure, electrochemical cycling conditions, crystallographic changes in the active materials, and resulting mechanical stresses have been elucidated, relatively little is known about the composition-dependency of the key physical properties.…”

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confidence: 99%

Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of Li_XCoO₂

Swallow

Woodford

McGrogan

et al. 2014

J. Electrochem. Soc.

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Mechanical degradation of lithium-ion battery (LIB) electrodes has been correlated with capacity fade and impedance growth over repeated charging and discharging. Knowledge of how the mechanical properties of materials used in LIBs are affected by electrochemical lithiation and delithiation could provide insight into design choices that mitigate mechanical damage and extend device lifetime. Here, we measured Young's modulus E, hardness H, and fracture toughness K Ic via instrumented nanoindentation of the prototypical intercalation cathode, Li X CoO 2 , after varying durations of electrochemical charging. After a single charge cycle, E and H decreased by up to 60%, while K Ic decreased by up to 70%. Microstructural characterization using optical microscopy, Raman spectroscopy, X-ray diffraction, and further nanoindentation showed that this degradation in K Ic was attributable to Li depletion at the material surface and was also correlated with extensive microfracture at grain boundaries. These results indicate that K Ic reduction and irreversible microstructural damage occur during the first cycle of lithium deintercalation from polycrystalline aggregates of Li X CoO 2 , potentially facilitating further crack growth over repeated cycling. Such marked reduction in K Ic over a single charge cycle also yields important implications for the design of electrochemical shock-resistant cathode materials. Energy storage is an enabling technology for electrified transportation and for large-scale deployment of renewable energy resources such as solar and wind. For many applications, non-aqueous ionintercalation chemistries such as Li-ion are attractive for their high energy density and electrochemical reversibility. However, the electrode materials used in ion-intercalation batteries undergo significant composition changes-which correlate to high storage capacity-that can induce structural changes and mechanical stresses; these changes can degrade battery performance metrics such as power, achievable storage capacity, and lifetime.1-8 Microstructural damage has been observed directly in numerous electrode materials subjected to electrochemical cycling, both within single crystals (or grains) and among polycrystalline aggregates. 4,5,[7][8][9][10][11][12][13][14][15] While the relationships among electrode microstructure, electrochemical cycling conditions, crystallographic changes in the active materials, and resulting mechanical stresses have been elucidated, relatively little is known about the composition-dependency of the key physical properties. Numerous models have been developed to predict mechanical deformation in ion-storage materials during electrochemical cycling, as recently reviewed by Mukhopadhyay and Sheldon. 16 The quantitative utility of such models is dependent on measured elastoplastic properties, particularly the fracture toughness of these materials. To date, few experimental measurements of fracture toughness K Ic of battery materials have been reported; [17][18][19][20] similarly, few measureme...

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mentioning

confidence: 99%

Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of Li_XCoO₂

Swallow

Woodford

McGrogan

et al. 2014

J. Electrochem. Soc.

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“…Because this ratio is directly related to the state of charge (SOC) at the time that the cell was disassembled, it is possible, in principle, to compare this to the electrochemical SOC. If discrepancies between the two kinds of SOC values, which will be presented elsewhere, are noted, this information could be used to determine the degree of particle isolation, whereby certain regions of the cathode are no longer accessible to the cell (17).…”

Section: Resultsmentioning

confidence: 99%

Solid State Multinuclear Magnetic Resonance Investigation of Electrolyte Decomposition Products on Lithium-Ion Electrodes

et al. 2012

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Solid electrolyte interphase (SEI) formation in lithium ion cells prepared with advanced electrolytes is investigated by solid state multinuclear (7Li, 19F, 31P) magnetic resonance (NMR) measurements of electrode materials harvested from cycled cells subjected to an accelerated aging protocol. The electrolyte composition is varied to include the addition of fluorinated carbonates and triphenyl phosphate (TPP, a flame retardant). In addition to species associated with LiPF6 decomposition, cathode NMR spectra are characterized by the presence of compounds originating from the TPP additive. Substantial amounts of LiF are observed in the anodes as well as compounds originating from the fluorinated carbonates.

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“…Solid-state 7 Li NMR spectra were obtained by using MAS at room temperature without hetero-and/or homo-nuclear decoupling by RF irradiation. 15 Further, since the 7 Li peaks of simple lithium salts, such as, LiF, LiOH, and Li 2 CO 3 , appear at around 0 ppm, 18 the observed signal at 0 ppm may be ascribed to one of starting materials or by-product. The 7 Li shifts of the present materials are governed mostly by the paramagnetic shift (the Fermi-contact shift) and thus depend on sample temperature.…”

Section: Methodsmentioning

confidence: 99%

“…14,15 The two 7 Li MAS spectra are similar; they contain a sharp signal at ca. To reduce the paramagnetic broadening due to Ni 3+ , both studies employed low magnetic field (ca.…”

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confidence: 96%

⁷Li NMR Study on Irreversible Capacity of LiNi_0.8-xCo_0.15Al_0.05Mg_xO₂Electrode in a Lithium-Ion Battery

Murakami¹,

Shimoda²,

Ukyo³

et al. 2015

J. Electrochem. Soc.

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Effects of magnesium and the charge/discharge process on the local structure of LiNi 0.8-x Co 0.15 Al 0.05 Mg x O 2 (x = 0, 0.05, 0.10) were examined by 7 Li MAS NMR. Two distinct 7 Li signals were observed at ca. 660 ppm and at ca. 570 ppm for the x = 0 material by the combined use of ultra-fast MAS (100 kHz) and high magnetic field (14 T). We attributed these two signals to two Ni-rich domains for the x = 0 material; the former Li signal is assigned to the Li site, whose local structure is expressed formally as LiNiO 2 and the latter to LiNi 0.83 (Co/Al) 0.17 O 2 . The intensities of these Ni-rich domains reduce significantly upon slight addition of magnesium. This leads us to conclude that magnesium preferably replaces nickel in the Ni-rich domains. After the first charge/discharge process, the signal intensities at 500∼750 ppm assigned to the Ni-rich domains in the x = 0 material decrease appreciably. From this, we conclude that the lithium ions responsible for the irreversible capacity after the first cycle belong to the Ni-rich domains, and the reduction of the amount of the Ni-rich domains due to magnesium substitution is responsible for the improved cyclic performance of the x > 0 material as a positive electrode material.

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Investigation of particle isolation in Li-ion battery electrodes using 7Li NMR spectroscopy

Cited by 29 publications

References 17 publications

Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of Li_XCoO₂

Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of Li_XCoO₂

Solid State Multinuclear Magnetic Resonance Investigation of Electrolyte Decomposition Products on Lithium-Ion Electrodes

⁷Li NMR Study on Irreversible Capacity of LiNi_0.8-xCo_0.15Al_0.05Mg_xO₂Electrode in a Lithium-Ion Battery

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Investigation of particle isolation in Li-ion battery electrodes using 7Li NMR spectroscopy

Cited by 29 publications

References 17 publications

Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of LiXCoO2

Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of LiXCoO2

Solid State Multinuclear Magnetic Resonance Investigation of Electrolyte Decomposition Products on Lithium-Ion Electrodes

7Li NMR Study on Irreversible Capacity of LiNi0.8-xCo0.15Al0.05MgxO2Electrode in a Lithium-Ion Battery

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Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of Li_XCoO₂

Effect of Electrochemical Charging on Elastoplastic Properties and Fracture Toughness of Li_XCoO₂

⁷Li NMR Study on Irreversible Capacity of LiNi_0.8-xCo_0.15Al_0.05Mg_xO₂Electrode in a Lithium-Ion Battery