Effect of CO2 on layered Li1+zNi1−x−yCoxMyO2 (M=Al, Mn) cathode materials for lithium ion batteries

Shizuka, Kenji; Kiyohara, Chikara; Shima, Kunihisa; Takeda, Yasuo

doi:10.1016/j.jpowsour.2007.01.013

Cited by 131 publications

(107 citation statements)

References 10 publications

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“…The most common impurities which can be formed by storage at ambient air are hydroxides via the reaction of the NMC surface with humidity as well as carbonates via the reaction of CO 2 with the initially formed surface hydroxides. It is known that the formation of surface impurities is more significant on Ni-rich NMC materials, [16][17][18][19]21,22 which would be consistent with the observed unchanged voltage profile and capacity after one year of ambient storage for NMC111 (see text below) in contrast to NMC811. The formation of hydroxide/carbonate surface impurities on Ni-rich surfaces could also explain the observed initial voltage peak feature, as these would likely form an insulating and therefore resistive layer covering the active material particles.…”

Section: Resultssupporting

confidence: 71%

“…The formation of NiCO 3 species is in contrast to the literature, in which the carbonate species are typically assigned to Li 2 CO 3 , 12,13,15-19,22 yet no clear evidence was provided for this assumption. Interestingly, Shizuka et al 18 and Liu et al 22 reported for both NCA and LiNiO 2 a partial reduction of Ni 3+ to Ni 2+ upon storage, yet they still assumed the carbonate species to be Li 2 CO 3 . However, if Li + is removed from the layered oxide structure, an oxidation of the Ni-ions would be expected.…”

Section: Discussionmentioning

confidence: 99%

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Effect of Ambient Storage on the Degradation of Ni-Rich Positive Electrode Materials (NMC811) for Li-Ion Batteries

Jung

Morasch

Karayaylalı

et al. 2018

J. Electrochem. Soc.

337

415

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is one of the high-energy positive electrode (cathode) materials for next generation Li-ion batteries. However, compared to the structurally similar LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC111), it can suffer from a shorter lifetime due to its higher surface reactivity. This work studied and compared the formation of surface contaminations on NMC811 and NMC111 when stored under ambient conditions using electrochemical cycling, Raman spectroscopy, and X-ray photoelectron spectroscopy. NMC811 was found to develop a surface layer of up to ∼10 nm thickness that was mostly composed of nickel carbonate species mixed with minor quantities of hydroxide and water after ambient storage for 1 year, while no significant changes were observed on the NMC111 surface. The amount of carbonate species was quantified by gas chromatographic (GC) detection of carbon dioxide generated when the NMC particles were dispersed in hydrochloric acid. Surface impurity species formed on NMC811 upon ambient storage not only lead to a significant delithiation voltage peak in the first charge, but also markedly reduce the cycling stability of NMC811-graphite cells due to significantly growing polarization of the NMC811 electrode.

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Section: Resultssupporting

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Effect of Ambient Storage on the Degradation of Ni-Rich Positive Electrode Materials (NMC811) for Li-Ion Batteries

Jung

Morasch

Karayaylalı

et al. 2018

J. Electrochem. Soc.

337

415

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“…In air and CO 2 , the formation of lithium (bi)carbonate and hydroxide coatings on z E-mail: abraham@anl.gov oxide surfaces has been reported. At advanced stages of weathering, this coating (that can grow to be > 10 nm thick) 14 can be observed using electron microscopy, X-ray powder diffraction (XRD) 16,17,[20][21][22] and infrared spectroscopy.14,15 As the material delithiates, repulsion between the oxygen layers increases and the lattice expands along the crystallographic c axis (that is orthogonal to the TM-O planes). [13][14][15][16][17][18]23 In some studies, in addition to the XRD pattern of the parent material, poorly resolved Bragg peaks from a cubic phase were observed, which was attributed either to LiNi 2 O 4 spinel 13,14 28 Most authors, however, suggest that such cation exchange plays a minor role if any at all, favoring instead a redox process that is fully analogous to the one occurring in electrochemical delithiation.…”

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confidence: 99%

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confidence: 99%

Chemical Weathering of Layered Ni-Rich Oxide Electrode Materials: Evidence for Cation Exchange

Shkrob

Gilbert

Phillips

et al. 2017

J. Electrochem. Soc.

141

160

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Lithiated ternary oxides containing nickel, cobalt, and manganese are intercalation compounds that are used as positive electrodes in high-energy lithium-ion batteries. These oxides undergo changes, when they are stored in humid air or exposed to moisture, that adversely affect their electrochemical performance. There is a new urgency to better understanding of these "weathering" mechanisms as manufacturing moves toward a more environmentally benign aqueous processing of the positive electrode. Delithiation of the oxide and the formation of lithium salts (such as hydroxides and carbonates) coating the surface, are known to occur during moisture exposure. The redox reactions which follow this delithiation are believed to trigger all the other transformations. In this article we suggest another possibility: namely, the proton -lithium exchange. We argue that this hypothesis provides a simple, comprehensive rationale for our observations, which include contraction of the c-axis (unit cell) lattice parameter, rock salt phase formation in the subsurface regions, presence of amorphous surface films, and the partial recovery of oxide capacity during electrochemical relithiation. The detrimental effects of water exposure need to be mitigated before aqueous processing of the positive electrode can find widespread adoption during cell manufacturing. Improving the performance of lithium-ion batteries (LIBs) for electrically powered vehicles gives urgency to the development of high-capacity, high-voltage electrode materials, and layered Ni-rich oxides are presently among the most technological advanced materials that allow operation above +4.0 V vs Li + /Li. 1 Such materials (also known as NCMxyz materials) have the general composition of LiNi x/10 Co y/10 Mn z/10 O 2 , where x+y+z = 10. In these ternary oxides, the manganese stays in the Mn 4+ state during cell cycling, and the capacity mainly originates from the Ni 2+ /Ni 3+ and Ni 3+ /Ni 4+ redox couples. The monolayers of octahedra containing transition metal (TM) ions form a structural scaffold with the layers of mobile Li + ions placed in between. The crystalline material retains the structure of the progenitor material of the family, viz. α-LiCoO 2 , 2 with the unit cell belonging to the rhombohedral R(-3)m space group. During electrochemical cycling, the lithium ions intercalate into (and deintercalate from) the layered crystals as the redox state of (mainly the) nickel ions changes to provide the overall charge neutrality.In this study, we examine one such material, NCM523, which represents a particular trade-off between the cycling rate (that improves with Co content), safety (that improves with Mn content), and capacity (that increases with Ni content).1 The safety concerns mainly relate to the thermal and chemical stability, including oxidation of the organic electrolyte by catalytic centers at the oxide surface 3 and phase transitions in the delithiated material that occur when a significant fraction of nickel ions is reduced to Ni 2+ ions and molecular oxygen ...

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“…In our previous work, the result of XPS for NCA before and after CO 2 exposure indicated the reduction of Ni 3+ to Ni 2+ occurred by the reaction with CO 2 (9). From this result, we concluded that the difference of CO 2 absorptivity should be caused by difference of Ni valence in cathode materials.…”

Section: Resultsmentioning

confidence: 73%