Analysis of the cubic spinel region of the Li–Co–Mn oxide pseudo-ternary system

Brown, Colby; McCalla, Eric; Dahn, J. R.

doi:10.1016/j.ssi.2013.09.051

Cited by 13 publications

(18 citation statements)

References 13 publications

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“…The size and shape of the spinel solid solution areas shown in figure 2 are broadly similar to those reported in [1,10]. Direct comparison is difficult because of the very different synthesis conditions used.…”

Section: Resultssupporting

confidence: 77%

Spinel–rock salt transformation in LiCoMnO _{4−
δ}

et al. 2016

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The transformation on heating LiCoMnO4, with a spinel structure, to LiCoMnO3, with a cation-disordered rock salt structure, accompanied by loss of 25% of the oxygen, has been followed using a combination of diffraction, microscopy and spectroscopy techniques. The transformation does not proceed by a topotactic mechanism, even though the spinel and rock salt phases have a similar, cubic close-packed oxygen sublattice. Instead, the transformation passes through two stages involving, first, precipitation of Li2MnO3, leaving behind a Li-deficient, Co-rich non-stoichiometric spinel and, second, rehomogenization of the two-phase assemblage, accompanied by additional oxygen loss, to give the homogeneous rock salt final product; a combination of electron energy loss spectroscopy and X-ray absorption near edge structure analyses showed oxidation states of Co2+ and Mn3+ in LiCoMnO3. Subsolidus phase diagram determination of the Li2O-CoOx-MnOy system has established the compositional extent of spinel solid solutions at approximately 500°C.

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Section: Resultssupporting

confidence: 77%

Spinel–rock salt transformation in LiCoMnO _{4−
δ}

et al. 2016

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“…Since the lattice parameter of the spinel phase in the regular-cooled sample of composition I was close to the value of Co 3 O 4 , it matches the results predicted by the phase diagrams of previous work. 13 It is expected that increasing the cobalt content of cubic spinel materials will decrease their lattice parameter, given that Co 3 O 4 has such a small lattice parameter. The fitted lattice parameters reported in Figure 9 follow this pattern, as the lowest lattice parameters were measured for samples dispensed at the highest Co metal fraction of 0.30.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…3,4,13,14 A Cartesian Pixsys solution-processing robot was used to dispense arrays of combinatorial samples onto alumina plates (Pi-Kem, 96%) that were previously coated with stearic acid (Aldrich, 96%). Ammonium bicarbonate (Alfa Aesar, 98%) was added in order to induce coprecipitation of mixedmetal carbonates in each sample.…”

Section: ■ Experimental Proceduresmentioning

confidence: 99%

Combinatorial Study of the Li–Ni–Mn–Co Oxide Pseudoquaternary System for Use in Li–Ion Battery Materials Research

et al. 2015

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Combinatorial synthesis has proven extremely effective in screening for new battery materials for Li-ion battery electrodes. Here, a study in the Li-Ni-Mn-Co-O system is presented, wherein samples with nearly 800 distinct compositions were prepared using a combinatorial and high-throughput method to screen for single-phase materials of high interest as next generation positive electrode materials. X-ray diffraction is used to determine the crystal structure of each sample. The Gibbs' pyramid representing the pseudoquaternary system was studied by making samples within three distinct pseudoternary planes defined at fractional cobalt metal contents of 10%, 20%, and 30% within the Li-Ni-Mn-Co-O system. Two large single-phase regions were observed in the system: the layered region (ordered rocksalt) and cubic spinel region; both of which are of interest for next-generation positive electrodes in lithium-ion batteries. These regions were each found to stretch over a wide range of compositions within the Li-Ni-Mn-Co-O pseudoquaternary system and had complex coexistence regions existing between them. The sample cooling rate was found to have a significant effect on the position of the phase boundaries of the single-phase regions. The results of this work are intended to guide further research by narrowing the composition ranges worthy of study and to illustrate the broad range of applications where solution-based combinatorial synthesis can have significant impact.

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“…The in-situ cell was then assembled in the same away as coin cells. The cell was cycled at a rate of C/100 between 3.0-4.4 V for two cycles using the E-one Moli charger system, while diffraction patterns were collected in the scattering angle (2θ) range of [17][18][19][20] • Ex-situ X-ray diffraction and scanning electron microscopy.-Pouch cells with electrolyte containing 2% VC were discharged to ∼0 V after 200 cycles (between 3-4.1, 4.2, 4.3 or 4.4 V with a rate of C/5) and then disassembled. The electrodes were rinsed with dimethyl carbonate (DMC) (99%, Sigma) to remove any residual electrolyte.…”

Section: Methodsmentioning

confidence: 99%

“…The layered lithium Ni-Mn-Co oxides Li 1+x (Ni y Mn z Co (1-y-z) ) 1-x O 2 (NMC) are considered to be promising positive electrode materials. [15][16][17][18][19][20][21][22][23] In our previous report 24 and in numerous literature reports, 6,14,16,17,19,[25][26][27][28][29][30][31][32] it has been shown that the electrochemical performance of these lithium-rich layered materials is dependent on their structure and composition. The lithium-rich manganese-rich NMC materials with excess lithium in the transition metal layer can have extraordinary high specific capacity of more than 250 mAh/g with an average potential of ∼3.6 V (vs. Li + /Li) after an irreversible oxygen release activation process at ∼4.5 V (vs. Li + /Li).…”

mentioning

confidence: 99%

Study of the Failure Mechanisms of LiNi_0.8Mn_0.1Co_0.1O₂Cathode Material for Lithium Ion Batteries

Downie

et al. 2015

J. Electrochem. Soc.

432

372

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LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) can deliver a high capacity of ∼200 mAh/g with an average discharge potential of ∼3.8 V (vs. Li + /Li), making it a promising positive electrode material for high energy density lithium ion batteries. However, electrochemical tests from half cells and full cells show poor cycling performance when charged to potentials above 4.2 V. The calendar and cycle lifetimes of cells are affected by the structural stability of the active electrode materials as well as the parasitic reactions that occur in lithium ion batteries. In order to explore the major failure mechanisms of the material, half cells (coin cells) with control electrolyte and full cells (pouch cells) with control electrolyte and with selected electrolyte additives were tested over four different potential ranges. Isothermal microcalorimetry was used to explore the parasitic reactions and their potential dependence. In-situ and ex-situ X-ray diffraction and scanning electron microscopy were used to investigate the structural and morphological degradation of the materials over cycling. It was found that the dramatic c-axis change of the active material during charge and discharge may not be the major problem for cells that are cycled to higher potentials. The parasitic reactions that arise from the interactions between the electrolyte and the highly reactive delithiated cathode surface at high potentials are suggested as the main reason for the failure of cells cycled above 4.2 V. It should be possible to further improve the performance of NMC811 at high potentials by modifying the cathode surface and/or identifying and using electrolyte blends which reduce parasitic reactions. High energy density lithium ion batteries (LIBs) that are cheaper, safer, and with longer lifetimes need to be developed in order to meet the increasing demand for applications such as electric vehicles and large scale stationary energy storage. The energy density of LIBs can be increased by increasing the specific capacity and average potential of the cells. The calendar and cycle lifetimes of cells are affected by the structural stability of the active electrode materials as well as the parasitic reactions that occur in lithium ion batteries. The degree of lithium utilization of LiCoO 2 is limited to ∼70% in order avoid the O3 -H1-3 -O1 phase transformation when charged above 4.45 V.1 Parasitic reactions such as electrolyte oxidation at the cathode-electrolyte interface can ultimately cause cell failure.2-5 The rate of the parasitic reactions is related to both the catalytic role of the cathode surface which depends on its composition and surface area, 3,6 as well as on the stability of the electrolyte.2-5 Methods such as the use of electrolyte additives 7-11 and core-shell positive electrode materials [12][13][14] have been developed and studied to reduce the rate and extent of parasitic reactions, and hence increase capacity retention and lifetime of high-voltage Li-ion cells. The layered lithium Ni-Mn-Co oxides Li 1+x (Ni y Mn z Co (1-y-z) ) 1...

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Analysis of the cubic spinel region of the Li–Co–Mn oxide pseudo-ternary system

Cited by 13 publications

References 13 publications

Spinel–rock salt transformation in LiCoMnO _{4−
δ}

Spinel–rock salt transformation in LiCoMnO _{4−
δ}

Combinatorial Study of the Li–Ni–Mn–Co Oxide Pseudoquaternary System for Use in Li–Ion Battery Materials Research

Study of the Failure Mechanisms of LiNi_0.8Mn_0.1Co_0.1O₂Cathode Material for Lithium Ion Batteries

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Analysis of the cubic spinel region of the Li–Co–Mn oxide pseudo-ternary system

Cited by 13 publications

References 13 publications

Spinel–rock salt transformation in LiCoMnO 4− δ

Spinel–rock salt transformation in LiCoMnO 4− δ

Combinatorial Study of the Li–Ni–Mn–Co Oxide Pseudoquaternary System for Use in Li–Ion Battery Materials Research

Study of the Failure Mechanisms of LiNi0.8Mn0.1Co0.1O2Cathode Material for Lithium Ion Batteries

Contact Info

Product

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Spinel–rock salt transformation in LiCoMnO _{4−
δ}

Spinel–rock salt transformation in LiCoMnO _{4−
δ}

Study of the Failure Mechanisms of LiNi_0.8Mn_0.1Co_0.1O₂Cathode Material for Lithium Ion Batteries