In Situ Solid State<sup>7</sup>Li NMR Observations of Lithium Metal Deposition during Overcharge in Lithium Ion Batteries

Arai, Juichi; Okada, Yumika; Sugiyama, T.; Izuka, Misato; Gotoh, Kazuma; Takeda, Kazuyuki

doi:10.1149/2.0411506jes

Cited by 78 publications

(77 citation statements)

References 23 publications

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“…Finally, a lithium cation, used as a charge carrier in lithium batteries with graphite electrodes, could also be treated as an alternative magnetic probe of local aromaticity of ordered carbon systems . In addition, π– 7 Li + interactions are very important in molecular recognition, and 7 Li NMR spectroscopy is applied both in the solution and in the solid state …”

Section: Introductionmentioning

confidence: 99%

Local aromaticity mapping in the vicinity of planar and nonplanar molecules

Kupka

Gajda

Stobiński

et al. 2019

Magnetic Reson in Chemistry

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We report on nucleus‐independent magnetic shielding (NICS) scans over the centers of six‐ and five‐membered rings in selected metal phthalocyanines (MPc) and fullerene C60 for more accurate characterization of local aromaticity in these compounds. Detailed tests were conducted on model aromatic molecules including benzene, pyrrole, indole, isoindole, and carbazole and subsequently applied to H2Pc, ZnPc, Al(OH)Pc, and CuPc. Similar behavior of three selected magnetic probes, Bq, 3He, and 7Li+, approaching perpendicularly the ring centers, was observed. For better visualization of shielding zone over the centers of aromatic rings, we introduced a simple mathematical procedure: the first and second derivatives of scan curves with respect to magnetic probe position enabled their additional examination. It allowed an easier localization of curve minimum and discrimination between areas in space varying by the magnetic field magnitude and to illustrate local aromaticity of two different kinds of rings in MPc with better resolution. Our results supported earlier reports on very low aromaticity indexes of pyrrole ring incorporated into MPc and significant aromaticity of the central macrocycle. No direct dependence between harmonic oscillator model of aromaticity and NICS was observed. Instead, a correlation between position of scan curve minimum and its magnitude were observed. In addition, the NICS values and 3He chemical shifts in the middle of neutral C60 and C606− anion agreed well with the reported experimental NMR values for He@C60 and He@C606−.

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Section: Introductionmentioning

confidence: 99%

Local aromaticity mapping in the vicinity of planar and nonplanar molecules

Kupka

Gajda

Stobiński

et al. 2019

Magnetic Reson in Chemistry

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“…For the electrical connections, meshes attached to the electrodes have been generally used [11][12][13][14][15][16][17] . Conductive foils for the connections are possible as well, but sealing is known to be more challenging [18][19][20] . Bag cells are flexible and low-cost.…”

Section: Introductionmentioning

confidence: 99%

Long-run in operando NMR to investigate the evolution and degradation of battery cells

Kayser

Mester

Mertens

et al. 2018

Phys. Chem. Chem. Phys.

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To improve the lifetime of lithium-ion batteries, a detailed understanding of the degradation mechanisms is essential. Nuclear magnetic resonance (NMR) is able to unravel the reversible as well as irreversible transient changes of composition, shape and morphology in a battery cell. Using a newly developed cylindrical battery container free of metallic components in combination with a numerically optimized saddle coil, in operando NMR investigations of battery cells over hundreds of charge/discharge cycles are presented. Alternating with NMR data acquisition, electrochemical impedance spectra (EIS) can be recorded, which enables correlative analysis of the two techniques. Long-run in operando NMR measurements on a Li metal vs. graphite cell reveal the formation and evolution of mossy and dendritic Li microstructures over a period of 1000 h, which illustrates the capabilities of NMR to identify dendrite mitigation strategies in cells operated under realistic conditions.

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“…16 We developed an in-situ solid-state 7 Li NMR method using a small laminated full cell composed of actual electrodes to analyze the cell reaction without disassembling the cell. 18,19 The NMR method can be used to investigate the state of Li atoms regardless of whether they exist as ions in an electrolyte or they are stored in electrodes [especially in graphite negative electrode material as a graphite intercalation compound (GIC)]. The NMR method can also be used to investigate accidentally deposited Li metal.…”

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confidence: 99%

Study of Li Metal Deposition in Lithium Ion Battery during Low-Temperature Cycle Using In Situ Solid-State⁷Li Nuclear Magnetic Resonance

Arai

Nakahigashi

2017

J. Electrochem. Soc.

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The influences of temperature and cell operation conditions on Li metal deposition in lithium ion batteries were studied by in-situ solid-state 7 Li nuclear magnetic resonance (NMR) spectroscopy. The rates of Li metal deposition during the low-temperature cycle with two charge-discharge operation modes, i.e., continuous current and pulse current, were estimated for temperatures of 5, 0, and −5 • C. Close values of activation energies were obtained for the capacity fading rate and the Li metal deposition rate, suggesting that Li metal deposition is the main cause of capacity fading in low-temperature cycles. The amounts of Li stored in the negative electrode and Li metal deposited during the low-temperature cycle were estimated and are discussed to understand the capacity fading mechanism. The pulse current mode cycle did not lead to any Li metal deposition at low temperatures. Lithium ion batteries (LIBs) are superior energy storage devices from the viewpoint of energy density, wide range of cell voltages derived from a variety of electrode materials, and further possibility of energy density improvement by developing innovative electrode materials.1,2 LIBs have been widely used in portable applications, and their use is extending to electric vehicles (EVs) and hybrid electric vehicles (HEVs). However, these EV applications require high energy densities to realize long driving distances, a long battery life to preserve the performance of vehicles during their lifecycle, and cost reduction. The temperature performance of LIBs also influences the vehicle performance, especially the limitation of low-temperature regeneration.3,4 This prevents full usage of LIB performance. LIBs are degraded by damage to the active material at high temperatures and by Li metal deposition at low temperatures.5-8 Moreover, the safety of LIBs is worsened by Li metal deposition.9,10 Thus, understanding the behavior of Li metal deposition at low temperatures is crucial for optimizing charging protocols and assuring safe and durable use of LIBs.Li metal deposition has been studied using optical microscopy and scanning electron microscopy with specially designed electrochemical cells at ambient temperature, which has allowed observation of the growth of dendritic Li deposition and estimation of the volume during operation.11-13 However, those cells were open structures that did not consider actual cell circumstances, such as the limited volume of electrolyte and the cell pressure, which restrains the movement of Li ions. Li metal deposition has also been evaluated by weighing the electrode and measuring the nuclear magnetic resonance (NMR) of a commercial 18650 battery after cycling.14-16 However, these studies are post molten analysis with disassembling the cell and affected the results by sample preparation.17 Furthermore, deposited Li metal sometimes intercalates into graphite, thus missing the chance to acquire a true sample. 16 We developed an in-situ solid-state 7 Li NMR method using a small laminated full cell composed of actual ele...

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In Situ Solid State⁷Li NMR Observations of Lithium Metal Deposition during Overcharge in Lithium Ion Batteries

Cited by 78 publications

References 23 publications

Local aromaticity mapping in the vicinity of planar and nonplanar molecules

Local aromaticity mapping in the vicinity of planar and nonplanar molecules

Long-run in operando NMR to investigate the evolution and degradation of battery cells

Study of Li Metal Deposition in Lithium Ion Battery during Low-Temperature Cycle Using In Situ Solid-State⁷Li Nuclear Magnetic Resonance

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In Situ Solid State7Li NMR Observations of Lithium Metal Deposition during Overcharge in Lithium Ion Batteries

Cited by 78 publications

References 23 publications

Local aromaticity mapping in the vicinity of planar and nonplanar molecules

Local aromaticity mapping in the vicinity of planar and nonplanar molecules

Long-run in operando NMR to investigate the evolution and degradation of battery cells

Study of Li Metal Deposition in Lithium Ion Battery during Low-Temperature Cycle Using In Situ Solid-State7Li Nuclear Magnetic Resonance

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Product

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In Situ Solid State⁷Li NMR Observations of Lithium Metal Deposition during Overcharge in Lithium Ion Batteries

Study of Li Metal Deposition in Lithium Ion Battery during Low-Temperature Cycle Using In Situ Solid-State⁷Li Nuclear Magnetic Resonance