Surface Degradation and Chemical Electrolyte Oxidation Induced by the Oxygen Released from Layered Oxide Cathodes in Li−Ion Batteries

Leanza, Daniela; Mirolo, Marta; Vaz, C. A. F.; Novák, Petr; Kazzi, Mario El

doi:10.1002/batt.201800126

Cited by 37 publications

(37 citation statements)

References 48 publications

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“…The use of LTO as the counter electrode is essential to track the possible migration/diffusion of organic and/or inorganic species formed at the surface of the cathode in the case of electrolyte oxidation, as was proposed on similar cathode materials. [23][24][25] With this approach, we first shed light on the reaction mechanism of the adventitious Li 2 CO 3 , its evolution upon cycling, and its impact on the electrochemical cycling behavior. Second, we identify the TMs' oxidation state upon cycling at the surface and deeper in the bulk of the NCA particles, as well as the contribution of the oxygen in the charge compensation at high voltages.…”

Section: Introductionmentioning

confidence: 99%

Multi-length-scale x-ray spectroscopies for determination of surface reactivity at high voltages of LiNi0.8Co0.15Al0.05O2 vs Li4Ti5O12

Mirolo

Vaz

Novák

et al. 2020

The Journal of Chemical Physics

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The surface evolution of LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) and Li 4 Ti5O 12 (LTO) electrodes cycled in a carbonate-based electrolyte was systematically investigated using the high lateral resolution and surface sensitivity of x-ray photoemission electron microscopy combined with x-ray absorption spectroscopy and x-ray photoelectron spectroscopy. On the cathode, we attest that the surface of the pristine particles is composed of adventitious Li 2 CO 3 together with reduced Ni and Co in a +2 oxidation state, which is directly responsible for the overpotential observed during the first de-lithiation. This layer decomposes at 3.8 V vs Li + /Li, leaving behind a fresh surface with Ni and Co in a +3 oxidation state. The charge compensation upon Li + extraction takes place above 4.0 V and is assigned to the oxidation of both Ni and oxygen, while Co remains in a +3 oxidation state during the whole redox process. We also identified the formation of an inactive surface layer already at 4.3 V, rich in reduced Ni and depleted in oxygen. However, at 4.9 V, NiO-like species are detected accompanied with reduced Co. Despite the highly oxidative potential, the surface of the cathode after long cycling is free of oxidized solvent byproducts but contains traces of LiPF 6 byproducts (LiF and POxFy). On the LTO counter electrode, transition metals are detected only after long cycling vs NCA to 4.9 V as well as PVdF and LiPF 6 byproducts originating from the cathode. Finally, harvested cycled electrodes prove that the influence of the crosstalk on the electrochemical performance of LTO is limited.

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Section: Introductionmentioning

confidence: 99%

Multi-length-scale x-ray spectroscopies for determination of surface reactivity at high voltages of LiNi0.8Co0.15Al0.05O2 vs Li4Ti5O12

Mirolo

Vaz

Novák

et al. 2020

The Journal of Chemical Physics

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“…However, the increased voltage cutoffs also aggravate material decomposition and impede the battery performance [1][2][3] . It is commonly accepted that these transitions from layered to spinel or rock-salt phases, and migration/segregation of transition metals (TMs) induce structural reconstruction that facilitates capacity fade [4][5][6] . During delithiation, the layered oxide material may transform into a spinel-type phase and then to a completely disordered rock salt-type structure, which is believed to inhibit the diffusion of lithium ions.…”

mentioning

confidence: 99%

Surface regulation enables high stability of single-crystal lithium-ion cathodes at high voltage

et al. 2020

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Single-crystal cathode materials for lithium-ion batteries have attracted increasing interest in providing greater capacity retention than their polycrystalline counterparts. However, after being cycled at high voltages, these single-crystal materials exhibit severe structural instability and capacity fade. Understanding how the surface structural changes determine the performance degradation over cycling is crucial, but remains elusive. Here, we investigate the correlation of the surface structure, internal strain, and capacity deterioration by using operando X-ray spectroscopy imaging and nano-tomography. We directly observe a close correlation between surface chemistry and phase distribution from homogeneity to heterogeneity, which induces heterogeneous internal strain within the particle and the resulting structural/performance degradation during cycling. We also discover that surface chemistry can significantly enhance the cyclic performance. Our modified process effectively regulates the performance fade issue of single-crystal cathode and provides new insights for improved design of high-capacity battery materials.

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“…The thermodynamic driving force for the oxidation of the lattice oxygen anion can thus trigger an increased dissolution of the metal cation in a reduced state with increasing electrode potential, a phenomenon which might appear paradoxical at first glance. Similar corrosion processes are known from cathode materials for Li-ion batteries 34 .…”

Section: E Lattice Oxygen Evolution Reaction (Loer)mentioning

confidence: 59%

“…However, standard conditions define unbalanced concentrations for the reactant and product side of reaction (19), with c H2O, = 55. 34 In contrast, ∆ r G w is reduced by the concentration imbalance between reactants and products due to the particular choice of the standard concentration of c H + = c OH − = 1 mol/L.…”

Section: Reaction Coordinatementioning

confidence: 99%

Ideal Gas Reference for Association and Dissociation Reactions: II. Kinetic Reference Potentials and Concentration Bias in Electrolysis

Binninger

Heinritz²,

Mohamed³

2021

Preprint

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The ideal gas reference for association and dissociation reactions, developed in the first part of this series, is applied to electrochemical reactions. We obtain an ideal Nernst equation that quantifies the unspecific voltage contribution arising from an imbalance between the reactant and product concentrations of an electrochemical reaction for the given conditions. Subtracting this concentration bias from the equilibrium voltage/potential, we define the "kinetic reference voltage/potential" where the reactant and product states are "aligned" within the potential energy landscape of the system. The kinetic reference voltage/potential is a fundamental descriptor for a given electrochemical reaction, providing an intrinsic reference point which is most relevant in cases where the (standard) equilibrium voltage/potential is biased by large concentration differences between the reactant and product side. This is most dramatic for the case of water electrolysis, where the gaseous H2 and O2 product concentrations are several orders of magnitude smaller than the liquid water reactant concentration. The respective equilibrium voltage is strongly biased by the low H2 and O2 concentrations, although the latter do not directly influence the forward water splitting rate. The unbiased kinetic reference voltage agrees remarkably well with the experimentally observed onset of macroscopic water splitting rates. We further extend our analysis to the kinetic reference potentials of the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and lattice oxygen evolution reaction (LOER), providing an unconventional perspective on pH-dependent overpotentials, anticipated electrocatalysis improvements, and kinetic stabilization of electrocatalyst materials.

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Surface Degradation and Chemical Electrolyte Oxidation Induced by the Oxygen Released from Layered Oxide Cathodes in Li−Ion Batteries

Cited by 37 publications

References 48 publications

Multi-length-scale x-ray spectroscopies for determination of surface reactivity at high voltages of LiNi0.8Co0.15Al0.05O2 vs Li4Ti5O12

Multi-length-scale x-ray spectroscopies for determination of surface reactivity at high voltages of LiNi0.8Co0.15Al0.05O2 vs Li4Ti5O12

Surface regulation enables high stability of single-crystal lithium-ion cathodes at high voltage

Ideal Gas Reference for Association and Dissociation Reactions: II. Kinetic Reference Potentials and Concentration Bias in Electrolysis

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