Thermo-Chemical Process Associated with Lithium Cobalt Oxide Cathode in Lithium Ion Batteries

Doh, Chil‐Hoon; Veluchamy, A.

doi:10.5772/9116

Cited by 3 publications

(4 citation statements)

References 51 publications

(53 reference statements)

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“…Cathode oxide materials can reduce in exothermic disproportionation reactions e.g., lithium cobalt oxide breakdown outlined in Equation (1) [13,16]. Charged LixCoO2 (lithiated) can decompose, releasing oxygen at elevated temperatures [17]. Equation (1) shows the complete reduction to cobalt metal that will only occur if sufficient reducing agent (solvent) is present [16].…”

Section: The Thermal Runaway Cascadementioning

confidence: 99%

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Looking Deeper into the Galaxy (Note 7)

et al. 2018

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Li-ion cell designs, component integrity, and manufacturing processes all have critical influence on the safety of Li-ion batteries. Any internal defective features that induce a short circuit, can trigger a thermal runaway: a cascade of reactions, leading to a device fire. As consumer device manufacturers push aggressively for increased battery energy, instances of field failure are increasingly reported. Notably, Samsung made a press release in 2017 following a total product recall of their Galaxy Note 7 mobile phone, confirming speculation that the events were attributable to the battery and its mode of manufacture. Recent incidences of battery swelling on the new iPhone 8 have been reported in the media, and the techniques and lessons reported herein may have future relevance. Here we look deeper into the key components of one of these cells and confirm evidence of cracking of electrode material in tightly folded areas, combined with a delamination of surface coating on the separator, which itself is an unusually thin monolayer. We report microstructural information about the electrodes, battery welding attributes, and thermal mapping of the battery whilst operational. The findings present a deeper insight into the battery's component microstructures than previously disseminated. This points to the most probable combination of events and highlights the impact of design features, whilst providing structural considerations most likely to have led to the reported incidences relating to this phone.

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Section: The Thermal Runaway Cascadementioning

confidence: 99%

“…Charged Li x CoO 2 (lithiated) can decompose, releasing oxygen at elevated temperatures [17]. Equation (1) shows the complete reduction to cobalt metal that will only occur if sufficient reducing agent (solvent) is present [16].…”

Section: The Thermal Runaway Cascadementioning

confidence: 99%

Looking Deeper into the Galaxy (Note 7)

et al. 2018

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“…47 Biphenyl is suitable for use as an overcharge protective additive. 25,47,48,[51][52][53][54] Zhang et al reported that electro-polymerization of biphenyl at the temperature of 20 ± 5 • C occurs at the overcharge potential of 4.5-5.5V to form a conductive organic layer on cathode surface. 51 Mao et al reported the potential of polymerization of biphenyl at 4.7 V and at 21 • C. Biphenyl polymerization generates gas increasing the internal cell pressure.…”

Section: Effect Of Biphenyl Additive In the Electrolyte-electrolyte A...mentioning

confidence: 99%

Effects of Biphenyl Polymerization on Lithium Deposition in Commercial Graphite/NMC Lithium-Ion Pouch-Cells during Calendar Aging at High Temperature

Matadi

Géniès

Delaille

et al. 2017

J. Electrochem. Soc.

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Metallic lithium deposition is a typical aging mechanism observed in lithium-ion cells at low temperature and/or at high charge rate. Lithium dendrite growth not only leads to strong capacity fading, it also causes safety concerns such as short-circuits in the cell. In applications such as electric vehicles, the use of lithium-ion batteries combines discharging, long rest time and charging phases. It is foremost a matter of lifetime and safety from the perspective of the consumer or the investor. This study presents the post-mortem analyses of commercial 16 Ah Graphite/NMC (Nickel Manganese Cobalt layered oxide) Li-ion pouch cells. The cells were degraded by calendar aging at high temperature with or without periodic capacity tests. Unexpected local depositions of metallic lithium were confirmed on graphite electrodes by Nuclear Magnetic Resonance (NMR). Biphenyl, a monomer additive present in the liquid electrolyte, generates gas during its polymerization reaction occurring at high temperature and at high state of charge. As a result, dry-out areas are present between the electrodes leading to high impedance regions and no charge transfer between the electrodes. It is at the border of these areas that lithium metal is deposited. Lithium-ion batteries have the particularity of addressing applications as diverse as mobile electronic devices, electric vehicles or stationary applications of renewable energy. The use of rechargeable electrochemical cells is first and foremost a question of autonomy, lifetime and safety.1-3 So it is necessary to further increase the current performance of lithium-ion batteries.Deposition of metallic lithium or "lithium plating" is one of the aging mechanisms that is limiting the lifetime of lithium-ion batteries. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] In the literature, it is reported that the mechanism of lithium deposition generally occurs during the charge at low temperatures and/or at high current-rates. The intercalation of lithium ions into the structure of the negative electrode is in competition with the deposition of metallic lithium on top of the Solid Electrolyte Interphase (SEI). The morphology of the negative electrode, the porosity, the conductivity of the electrolyte and the state of lithiation are parameters to be considered. 8 This aging mechanism depends on intrinsic criteria of the components of the cell (active material, electrodes and electrolyte composition [21][22][23][24][25][26][27][28][29][30] ) and extrinsic to the system (temperature and charging current).Contact between the deposited lithium and the electrolyte (above the surface of the SEI) leads to the oxidation of lithium to form species such as ROCO 2 Li, Li 2 CO 3 or LiF. 15 The deposited lithium becomes isolated and electrochemically inactive and cannot participate in the electrochemical process at the electrodes. The deposit can grow in height from graphite particles and form dendrites which can pass through the separator and cause short circuit. This phenomena in combinatio...

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“…lithium cobalt oxide breakdown outlined in Equation 1 [13,16]. Charged LixCoO2 (lithiated) can decompose, releasing oxygen at elevated temperatures 17 . Equation 1 shows the complete reduction to cobalt metal that will only occur if sufficient reducing agent (solvent) is present [16].…”

Section: Of 11mentioning

confidence: 99%