Oxygen and transition metal involvement in the charge compensation mechanism of LiNi1/3Mn1/3Co1/3O2 cathodes

Petersburg, Cole; Li, Zheng; Chernova, Natasha A.; Whittingham, M. Stanley; Alamgir, Faisal M.

doi:10.1039/c2jm33392a

Cited by 56 publications

(45 citation statements)

References 25 publications

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“…The edge and pre-edge shape changes observed in this study, are consistent with previously reported results occurring at a slow cycling rate during the first cycle. 26,27 It is also seen that the preedge consists of two peaks, corresponding to the transition from the 1s orbital to an empty 3d orbital. 28 The double peak in the manganese pre-edge supports that the manganese ions are in the tetravalent state as only one pre-edge peak would be observed in the trivalent state.…”

Section: Resultsmentioning

confidence: 98%

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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Section: Resultsmentioning

confidence: 98%

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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“…[27,28] Whittingham et al proposed a mechanism whereby both, TM and oxygen, are involved in the charge compensation during charge/discharge in LiNi 1/3 Mn 1/3 Co 1/3 O 2 . [5] Hence the redox potentials of these Li-TM-oxides are directly related to the CT on the oxygen as well as TM ions with lithium de/intercalation.…”

Section: Introductionmentioning

confidence: 99%

“…Charge transfer (CT) between a transition metal (TM) atom and its ligands sensitively affect the properties of materials for various applications related to energy storage, [1][2][3][4][5] electrocatalysts, [6,7] optical materials, [8] magnetic materials, [9,10] and superconducting materials. [11] Thus, many efforts have been made to quantify and predict selective CT between TM atoms and coordinating species computationally and experimentally.…”

Section: Introductionmentioning

confidence: 99%

Calibrating transition-metal energy levels and oxygen bands in first-principles calculations: Accurate prediction of redox potentials and charge transfer in lithium transition-metal oxides

2015

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Transition metal (TM) oxides play an increasingly important role in technology today including applications such as catalysis, solar energy harvesting, and energy storage. In many of these applications, the details of their electronic structure near the Fermi level are critically important for their properties. We propose a first-principles based computational methodology for the accurate prediction of oxygen charge transfer in TM oxides and lithium TM (Li-TM) oxides. To obtain accurate electronic structures, the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional is adopted and the amount of exact Hartree-Fock exchange (mixing parameter) is adjusted to reproduce reference band gaps.We show that the HSE06 functional with optimal mixing parameter yields not only improved electronic densities of states but also better energetics (Li-intercalation voltages) for LiCoO 2 and LiNiO 2 as compared to GGA, GGA+U and standard HSE06.We find that the optimal mixing parameters for TM oxides are system-specific and correlate with the covalency (ionicity) of the TM species. Strong covalent (ionic) nature of TM-O bonding leads to lower (higher) optimal mixing parameters. We find that optimized HSE06 functionals predict stronger hybridization of the Co 3d and O 2p orbitals than GGA, resulting in a greater contribution from oxygen states to charge compensation upon delithiation in LiCoO 2 . We also find that the band gaps of Li-TM oxides increase linearly with the mixing parameter, enabling the straightforward determination of optimal mixing parameters based on GGA (α = 0.0) and HSE06 (α = 0.25) calculations. Our results also show that G 0 W 0 @GGA+U band gaps of TM oxides (MO, M = Mn, Co, Ni) and LiCoO 2 agree well with experimental references, suggesting that G 0 W 0 calculations can be used as a reference for the calibration of the mixing parameter in case no experimental band gap has been reported. 3

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“…During the charging (lithium deintercalation) and discharging (lithium intercalation) processes, nickel switches between Ni 2+ and Ni (2+x)+ oxidation states, where the x value is usually determined by the degree of lithium deintercalation, i.e., charging voltage cutoff in the galvanostatic or potentiostatic cycling. 12,24,31,32 At the end of discharge, the nickel oxidation state returns to Ni 2+ independent of changes in the crystal structure (Fig. 7a), so that detection of Ni 2+ in the TEY data is not proof per se of surface reconstruction to the rock salt structure.…”

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confidence: 99%

“…Both hard and so XAS has been widely adopted to track the change of electronic structures in battery materials. 30,31 An advantage of so XAS is the ability to investigate electronic structures of elements from surfaces to bulk, depending on the experimental setup. Probing depths range from about 1-2 nm for Auger electron yield (AEY) and 2-5 nm for total electron yield (TEY), to about 50 nm (or bulk) for uorescence electron yield (FY).…”

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confidence: 99%

Influence of synthesis conditions on the surface passivation and electrochemical behavior of layered cathode materials

et al. 2014

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Understanding the relationship between materials synthesis and electrochemical behaviors should provide valuable knowledge to further the advancement of lithium-ion batteries. In this work, layered cathode materials {e.g., LiNi 0.4 Mn 0.4 Co 0.18 Ti 0.02 O 2 (NMCs)} were prepared under three different annealing conditions, i.e., 900 C for 6 hours, 8 hours, and 12 hours, respectively. The resulting materials exhibit equivalent crystal structures and morphologies yet likely different surface chemical environments. These materials show distinctively different resistances against the surface passivation/ reconstruction (reduction of the transition metals in the layered structure to form rock-salt and/or spinel phases) during electrochemical cycling (2.0-4.7 V vs. Li + /Li). In general, the materials annealed for longer durations exhibited lower tendencies to form the surface passivation layer. Furthermore, the surface passivation became less severe when the electrode materials were cycled under mild conditions, such as slow constant current charging-discharging as opposed to cyclic voltammetry. The present study correlates the synthetic conditions with the surface instability and the electrochemical performance in cathode materials, and provides new insights into improving synthetic protocols for battery materials.

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Oxygen and transition metal involvement in the charge compensation mechanism of LiNi1/3Mn1/3Co1/3O2 cathodes

Cited by 56 publications

References 25 publications

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

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

Calibrating transition-metal energy levels and oxygen bands in first-principles calculations: Accurate prediction of redox potentials and charge transfer in lithium transition-metal oxides

Influence of synthesis conditions on the surface passivation and electrochemical behavior of layered cathode materials

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Oxygen and transition metal involvement in the charge compensation mechanism of LiNi1/3Mn1/3Co1/3O2 cathodes

Cited by 56 publications

References 25 publications

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

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

Calibrating transition-metal energy levels and oxygen bands in first-principles calculations: Accurate prediction of redox potentials and charge transfer in lithium transition-metal oxides

Influence of synthesis conditions on the surface passivation and electrochemical behavior of layered cathode materials

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Product

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

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