The influence of different conducting salts on the metal dissolution and capacity fading of NCM cathode material

Gallus, Dennis Roman; Wagner, Ralf; Hoffmann, B.; Nowak, Sascha; Cekic‐Laskovic, Isidora; Schmitz, René; Winter, Martin

doi:10.1016/j.electacta.2014.04.091

Cited by 212 publications

(226 citation statements)

References 30 publications

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“…9,11,13 While the error bars are hardly visibly for cutoff voltages ≤4.4 V and at low cycle numbers at a cutoff of 4.6 V, the error bars at higher cycle numbers significantly increase, which is due to the delayed onset of the so-called rollover-failure for the two cells. This failure mechanism was described previously by Dubarry et al and Burns et al and was shown to be due to growing kinetic resistances or more generally an impedance buildup.…”

Section: Resultsmentioning

confidence: 99%

“…For OEMS measurements, the ink was coated onto a H2013 polyolefin separator (Celgard, USA) or a stainless steel mesh (316 grade, 26 μm aperture, 25 μm wire diameter, The Mesh Company, UK) to allow for a short diffusion time of the evolved gases to the head-space of the OEMS cell and to the capillary leading to the mass spectrometer. 38,39 NMC622 electrodes containing 13 C-labeled carbon (99 % atom 13 C, Sigma-Aldrich, Germany) were prepared with the same composition as the ones containing Super C65, however, due to strong agglomeration of the carbon, the ink was prepared in a ball mill (Pulverisette 7, Fritsch, Germany) using zirconia balls with a diameter of 10 mm at 180 rpm for 60 minutes. After drying at 50…”

Section: Methodsmentioning

confidence: 99%

“…The NMC622-graphite cell with 13 C conductive carbon was charged to 4.8 V and subsequently discharged to 2.6 V (see Figure 10a). The capacity reached during the CC-phase was only 198 mAh/g NMC , i.e., ∼17% lower than for the NMC622 electrode with Super C65 (see Figure 8); this inferior electrode performance is likely caused by the strongly agglomerated structure of the 13 C-carbon, resulting in a poor electronic accessibility of the active material particles in the cathode. Nevertheless, also for this electrode, the release of oxygen can be clearly seen.…”

Section: Gas Analysis Of Nmc-li and Lnmo-li Half-cells By Oems-mentioning

confidence: 99%

“…9,10 Additionally, the sloped voltage profile requires very high voltages to achieve complete removal of lithium, which in turn can lead to electrolyte oxidation, surface film formation, and transition metal dissolution, ultimately diminishing the cycling stability. [11][12][13][14][15][16][17] For these reasons, the operating potential of NMC based cathode materials is nowadays limited to ∼4.3 V, restricting their capacities to much below their theoretical values. 5 In order to improve the accessible capacity at reasonable upper cutoff voltages, Ni-rich NMCs (Ni-content >> Mnand Co-content) recently became the focus of interest, as more lithium can be extracted from their structure within the same voltage window.…”

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Oxygen Release and Its Effect on the Cycling Stability of LiNi_xMn_yCo_zO₂(NMC) Cathode Materials for Li-Ion Batteries

Jung

Metzger

Maglia

et al. 2017

J. Electrochem. Soc.

1,009

1,278

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Layered LiNi x Mn y Co z O 2 (NMC) is a widely used class of cathode materials with LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC111) being the most common representative. However, Ni-rich NMCs are more and more in the focus of current research due to their higher specific capacity and energy. In this work we will compare LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC111), LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622), and LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) with respect to their cycling stability in NMC-graphite full-cells at different end-of-charge potentials. It will be shown that stable cycling is possible up to 4.4 V for NMC111 and NMC622 and only up to 4.0 V for NMC811. At higher potentials, significant capacity fading was observed, which was traced back to an increase in the polarization of the NMC electrode, contrary to the nearly constant polarization of the graphite electrode. Furthermore, we show that the increase in the polarization occurs when the NMC materials are cycled up to a high-voltage feature in the dq/dV plot, which occurs at ∼4.7 V vs. Li/Li + for NMC111 and NMC622 and at ∼4.3 V vs. Li/Li + for NMC811. For the latter material, this feature corresponds to the H2 → H3 phase transition. Contrary to the common understanding that the electrochemical oxidation of carbonate electrolytes causes the CO 2 and CO evolution at potentials above 4.7 V vs. Li/Li + , we believe that the observed CO 2 and CO are mainly due to the chemical reaction of reactive lattice oxygen with the electrolyte. This hypothesis is based on gas analysis using On-line Electrochemical Mass Spectrometry (OEMS), by which we prove that all three materials release oxygen from the particle surface and that the oxygen evolution coincides with the onset of CO 2 and CO evolution. Interestingly, the onsets of oxygen evolution for the different NMCs correlate well with the high-voltage redox feature at ∼4.7 V vs. Li/Li + for NMC111 and NMC622 as well as at ∼4.3 V vs. Li/Li + for NMC811. To support this hypothesis, we show that no CO 2 or CO is evolved for the LiNi 0.43 Mn 1.57 O 4 (LNMO) spinel up to 5 V vs. Li/Li + , consistent with the absence of oxygen release. Lastly, we demonstrate by the use of 13 C labeled conductive carbon that it is the electrolyte rather than the conductive carbon which is oxidized by the released lattice oxygen. Taking these findings into consideration, a mechanism is proposed for the reaction of released lattice oxygen with ethylene carbonate yielding CO 2 , CO, and Li-Ion batteries have recently been used as power supply for electric vehicles (EVs). In order to penetrate the mass market, a significant reduction in costs and further performance improvements have to be achieved to realize a longer driving range of EVs.1 The latter highly depends on the choice of the cathode active material, for which several potential materials exist, 2 of which layered lithium nickel manganese cobalt oxide (LiNi x Mn y Co z O 2 , NMC) is one of the most promising class of cathode materials.3 This is due to the high specific capacity and good stability of the lay...

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Gas Analysis Of Nmc-li and Lnmo-li Half-cells By Oems-mentioning

confidence: 99%

mentioning

confidence: 99%

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Oxygen Release and Its Effect on the Cycling Stability of LiNi_xMn_yCo_zO₂(NMC) Cathode Materials for Li-Ion Batteries

Jung

Metzger

Maglia

et al. 2017

J. Electrochem. Soc.

1,009

1,278

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“…There are several well-known failure modes or degradation processes in NMC electrodes, including "cross-over" of metal ions (Mn, Ni, Co) from the cathode to the anode, 6,7 micro-cracks in the particles during cycling, 8 loss of contact between particles, gas evolution, 9,10 phase transformations 11 and surface film formation. 12 We here shed light on yet another failure mechanism of NMC cathodes, triggered by the "cross-talk" between the electrodes, where species from the negative electrode dissolve into the electrolyte and deposit on the positive electrode.…”

mentioning

confidence: 99%

How the Negative Electrode Influences Interfacial and Electrochemical Properties of LiNi_1/3Co_1/3Mn_1/3O₂Cathodes in Li-Ion Batteries

Björklund

Brandell

Hahlin

et al. 2017

J. Electrochem. Soc.

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The cycle life of LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NMC) based cells are significantly influenced by the choice of the negative electrode. Electrochemical testing and post mortem surface analysis are here used to investigate NMC electrodes cycled vs. either Li-metal, graphite or Li 4 Ti 5 O 12 (LTO) as negative electrodes. While NMC-LTO and NMC-graphite cells show small capacity fading over 200 cycles, NMC-Li-metal cell suffers from rapid capacity fading accompanied with an increased voltage hysteresis despite the almost unlimited access of lithium. X-ray absorption near edge structure (XANES) results show that no structural degradation occurs on the positive electrode even after >200 cycles, however, X-ray photoelectron spectroscopy (XPS) results shows that the composition of the surface layer formed on the NMC cathode in the NMC-Li-metal cell is largely different from that of the other NMC cathodes (cycled in the NMC-graphite or NMC-LTO cells). Furthermore, it is shown that the surface layer thickness on NMC increases with the number of cycles, caused by continuous electrolyte degradation products formed at the Li-metal negative electrode and then transferred to NMC positive electrode. Li-ion batteries (LiBs) are widely used in applications where rechargeability of high energy density storage units is required, such as portable devices including consumer electronics, vehicles and space applications. It is beneficial that the components are as light-weight as possible for portable devices, thereby decreasing the energy required to transport the device. One widely used positive electrode material contributing to high energy density is LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NMC), either operating at a higher potential or having a larger practical specific capacity than the classical LiMn 2 O 4 and LiFePO 4 materials.1,2 NMC is also less costly than the LiCoO 2 alternative due to the decreased cobalt content.In commercial cells, NMC electrodes are most often cycled vs. graphite negative electrodes which has a low working potential, enabling a large potential difference between the electrodes. However, the low working potential is outside of the electrochemical stability window of most common electrolytes, leading to formation of a solid electrolyte interphase (SEI) layer on the anode surface. A corresponding but thinner layer could also form on the side of the positive electrode depending on the working potential of the cathode. 3,4 Lithium is consumed during SEI formation, which results in a decrease in the cell capacity and an increase in the cell resistance. The problems caused by SEI layer formation can be resolved by changing the negative electrode to an electrode working at a higher potential -within the electrochemical stability window of the electrolytesuch as lithium titanate (Li 4 Ti 5 O 12 ; LTO). Although the increased working potential decreases the energy density of the cell, cycle life is generally increased. The Li-metal anode is another negative electrode that is commonly used as counter/reference electrode, at le...

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The influence of different conducting salts on the metal dissolution and capacity fading of NCM cathode material

Cited by 212 publications

References 30 publications

Oxygen Release and Its Effect on the Cycling Stability of LiNi_xMn_yCo_zO₂(NMC) Cathode Materials for Li-Ion Batteries

Oxygen Release and Its Effect on the Cycling Stability of LiNi_xMn_yCo_zO₂(NMC) Cathode Materials for Li-Ion Batteries

How the Negative Electrode Influences Interfacial and Electrochemical Properties of LiNi_1/3Co_1/3Mn_1/3O₂Cathodes in Li-Ion Batteries

X‐ray Fluorescence Microscopy

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The influence of different conducting salts on the metal dissolution and capacity fading of NCM cathode material

Cited by 212 publications

References 30 publications

Oxygen Release and Its Effect on the Cycling Stability of LiNixMnyCozO2(NMC) Cathode Materials for Li-Ion Batteries

Oxygen Release and Its Effect on the Cycling Stability of LiNixMnyCozO2(NMC) Cathode Materials for Li-Ion Batteries

How the Negative Electrode Influences Interfacial and Electrochemical Properties of LiNi1/3Co1/3Mn1/3O2Cathodes in Li-Ion Batteries

X‐ray Fluorescence Microscopy

Contact Info

Product

Resources

About

Oxygen Release and Its Effect on the Cycling Stability of LiNi_xMn_yCo_zO₂(NMC) Cathode Materials for Li-Ion Batteries

Oxygen Release and Its Effect on the Cycling Stability of LiNi_xMn_yCo_zO₂(NMC) Cathode Materials for Li-Ion Batteries

How the Negative Electrode Influences Interfacial and Electrochemical Properties of LiNi_1/3Co_1/3Mn_1/3O₂Cathodes in Li-Ion Batteries