Surface Structure Evolution of LiMn<sub>2</sub>O<sub>4</sub> Cathode Material upon Charge/Discharge

Tang, Dingxiang; Sun, Yang; Yang, Zhenzhong; Ben, Liubin; Gu, Lin; Huang, Xuejie

doi:10.1021/cm501125e

Cited by 232 publications

(244 citation statements)

References 81 publications

(124 reference statements)

Supporting

Mentioning

210

Contrasting

Order By: Relevance

“…Lattice parameters of the pristine and cycled samples. [010]-irradiated sample demonstrates a region which is close to a rock-salt crystal structure in the middle of the expected monoclinic structure and its FFT also reveals the ±(002) forbidden refl ection, seen following cycling (Figure 6 c) Contrary to previous reports suggesting that structural transformations are confi ned to, or occur predominately at, the near-surface regions, [ 13,23,24,33 ] our STEM analysis reveals signifi cant areas with local spinel ordering far away from the surface of the electrochemically cycled particles. The STEM image contrast that would result from a Mn 3 O 4 -type spinel is essentially indistinguishable from that which would arise from a LiMn 2 O 4 spinel, differing only in the intensity of the tetrahedral Li site columns that results from partial occupancy by Mn.…”

Section: Discussionmentioning

confidence: 61%

On the Localized Nature of the Structural Transformations of Li₂MnO₃ Following Electrochemical Cycling

Phillips

Bareño

et al. 2015

Advanced Energy Materials

View full text Add to dashboard Cite

an end member of the x LiMO 2 •(1 − x ) Li 2 MnO 3 family of compounds, which is being investigated extensively for application as positive electrodes in high-energy batteries. [3][4][5] Pure Li 2 MnO 3 adopts a layered Li[Li 1/3 Mn 2/3 ]O 2 structure in which the Li + and Mn 4+ ions occupy the octahedral interstices of a cubic close-packed oxygen lattice. [ 6 ] Although rich in Li + , lithium extraction from this compound is difficult and typical experimental capacities are markedly lower than the theoretical value. [7][8][9] In addition, the oxide's performance degrades signifi cantly and irreversibly on electrochemical cycling. Several studies have discussed possible reasons for the oxide's behavior and performance degradation. These reasons include the simultaneous extraction of Li + and oxygen, oxidation of Mn 4+ to a higher valence, exchange of Li + /H + -especially during high-temperature cycling, reversible oxidation of the oxygen ions, oxygen vacancy creation followed by rearrangement of transition metal (TM) atoms, and the development of a lithium-depleted surface layer with reduced Mn ions. [10][11][12][13][14][15][16] In this article, we supplement previous spectroscopy and microscopy studies with data from scanning transmission electron microscopy (STEM)-based characterization of pristine, electrochemically cycled, and electron-irradiated Li 2 MnO 3 . Specifi cally, we use a combination of annular bight fi eld (ABF), low angle annular dark fi eld (LAADF), and high angle annular dark fi eld (HAADF) imaging to examine crystal structural changes, and electron energy loss spectroscopy (EELS) to determine Mn-ion valence changes. The microscopy data are complemented by synchrotron-based X-ray diffraction (XRD) data obtained at Argonne's Advanced Photon Source (APS). A viable model is presented which describes the structural/electronic transformations both on the oxide surface and in the bulk.Our data indicate that, upon electrochemical cycling, Li 2 MnO 3 undergoes structural and electronic transitions both in the near-surface regions and in the bulk of the oxide particles. Although complex and nonhomogeneous, the observed nanostructures can be primarily characterized by Mn atoms occupying formerly Li positions leading to spinel and/or disordered rock-salt crystal structures. The EELS data indicate severe oxygen loss and reduced Mn valence, especially at areas near the particle surfaces. The observations on the cycled samples Although the Li-excess layered-oxide Li 2 MnO 3 has a high theoretical capacity, structural transformations within the oxide during electrochemical cycling lead to relatively low experimental capacities, hindering its use in practical applications. Here, aberration-corrected scanning transmission electron microscopy/electron energy loss spectroscopy and high-resolution X-ray diffraction are used to characterize the oxide following electrochemical cycling. Microscopy reveals the coexistence of regions with local monoclinic, spinel, and rock-salt symmetries, indicating localized and inh...

show abstract

Section: Discussionmentioning

confidence: 61%

On the Localized Nature of the Structural Transformations of Li₂MnO₃ Following Electrochemical Cycling

Phillips

Bareño

et al. 2015

Advanced Energy Materials

View full text Add to dashboard Cite

show abstract

“…For example, the Mn dissolution rate from LMO is greater at high potentials (above 4 V vs. Li/Li + ) than at lower potentials (below 4 V vs. Li/Li + ), a fact which is inconsistent with the disproportionation concept, since the fraction of Mn 4+ cations in the LMO lattice increases with increasing potential. 13,17 While a very large number of studies in the literature report a variety of results on the oxidation state of Mn species in the negative or positive electrodes of cycled LMO-graphite cells, 11,[18][19][20][21] Mitigation measures for Mn dissolution.-Several mitigation measures for the dissolution of Mn ions and its consequences were proposed in the literature over the past two decades: electrolyte optimization by a judicious choice of additives; [26][27][28][29][30][31][32][33] elemental substitutions in the LMO lattice, 7,13,17,34,35 in order to increase the average oxidation state of the Mn ions; surface coatings on the active material powder or electrodes, in order to avoid direct contacts between electrode and electrolyte solution, and thus prevent HF and other acid attack on the active material; [36][37][38][39][40][41][42] chemically active binders; [43][44][45][46][47][48][49][50] an inorganic Mn ions scavenging barrier layer such as lithium titanate 51 or a solid Li-ion conducting and Mn ions blocking membrane 52 placed in the inter-electrode space; and the utilization of chemically activ...…”

Section: A6316mentioning

confidence: 99%

Review—Multifunctional Materials for Enhanced Li-Ion Batteries Durability: A Brief Review of Practical Options

Banerjee

Shilina

Ziv

et al. 2017

J. Electrochem. Soc.

View full text Add to dashboard Cite

Transition metal (TM) ions dissolution from positive electrodes, migration to and deposition on negative electrodes, followed by Mn-catalyzed reactions of solvents and anions, with loss of Li + ions, is a major degradation (DMDCR) mechanism in Li-ion batteries (LIBs) with spinel positive electrode materials. While the details of the DMDCR mechanism are still under debate, it is clear that HF and other acid species' attack is the main cause in solutions with LiPF 6 electrolyte. We first review the work on various mitigation measures for the DMDCR mechanism, now spanning more than two decades. We then discuss recent progress on our understanding of Mn species in electrolyte solutions and the extension of a mitigation measure first proposed by Tarascon and coworkers in 1999, namely chelation of TM cations, to Mn cation trapping, HF scavenging, and alkali metal ions dispensing multi-functional materials. We focus on practicable, drop-in technical solutions, based on placing such materials in the inter-electrode space, with significant benefits for LIBs performance: increased capacity retention during operation at room and above-ambient temperatures as well as robust (both maximally ionically conducting and electronically insulating) solid-electrolyte interfaces, having reduced charge transfer and film resistances at both negative and positive electrodes. We illustrate the multifunctional materials approach with both new and previously published data. We also discuss and offer our evaluation regarding the merits and drawbacks of the various mitigation measures, with an eye for practically relevant technical solutions capable to meet both the performance requirements and cost constraints for commercial LIBs, and end with recommendations for future work. Li-ion batteries (LIBs) dominate the global market for energystorage devices nowadays and are used in a variety of applications, ranging from portable consumer electronics, to electrical grid storage, to load-levelling and electrified vehicles.1 Electrified vehicles are the most demanding among all LIBs applications in terms of both duty cycle and durability, since the batteries are subjected to a wide range of temperatures and charging/discharging rates, while customers expect a 10 years lifetime. Incessant research on various positive and negative active materials resulted in several promising electrode materials with various crystal structures and chemistries being developed over the past decades, such as layered (LiCoO 2 , LiNi 1-x-y Co x Al y O 2 , Ni 1-x-y Co x Mn y O 2 ), spinel (LiMn 2 O 4 , a.k.a. LMO; LNi 0.5 Mn 1.5 O 2 , a.k.a. LNMO), and olivine (LiFePO 4, LiVPO 4 ) for positive, as well as graphite, silicon, silicon-oxide, and lithium titanate for negative electrodes.2 New developments in electrode materials notwithstanding, LIBs for automotive transportation still need considerable improvements in terms of both performance and durability. Among transition metal (TM) oxide cathodes, LiMn 2 O 4 spinel would be most suited for automotive power cells due to i...

show abstract

“…7-10, [41][42][43] There are three main stability areas for surfaces in Fig. 9: T3-(001), T2R-(111), and T3R-(111).…”

Section: Iii3 Stability Diagram For Bulk Lmo and Lmo Surfacesmentioning

confidence: 99%

Surface phase diagram and stability of (001) and (111)LiMn2O4spinel oxides

2015

View full text Add to dashboard Cite

The (001) and (111) surface structures of the LiMn 2 O 4 (LMO) spinel are examined using density functional theory (DFT) calculations within the generalized gradient approximation (GGA)+U approach. In order to clarify discrepancies in the literature for previous DFT calculations of these surfaces, we first carefully study the effects of surface termination/reconstruction, slab construction, and relaxation schemes, as well as magnetic ordering and U values for Mn on the calculated surface energies of LMO. We explain these discrepancies and show that the relaxation scheme and surface reconstruction play the key role in determining the relative stability of (001) and (111) surfaces. We have further analyzed the thermodynamic stability of LMO surfaces as a function of oxygen and lithium chemical potentials. We have found that the ratio of (001)

show abstract

Surface Structure Evolution of LiMn₂O₄ Cathode Material upon Charge/Discharge

Cited by 232 publications

References 81 publications

On the Localized Nature of the Structural Transformations of Li₂MnO₃ Following Electrochemical Cycling

On the Localized Nature of the Structural Transformations of Li₂MnO₃ Following Electrochemical Cycling

Review—Multifunctional Materials for Enhanced Li-Ion Batteries Durability: A Brief Review of Practical Options

Surface phase diagram and stability of (001) and (111)LiMn2O4spinel oxides

Contact Info

Product

Resources

About

Surface Structure Evolution of LiMn2O4 Cathode Material upon Charge/Discharge

Cited by 232 publications

References 81 publications

On the Localized Nature of the Structural Transformations of Li2MnO3 Following Electrochemical Cycling

On the Localized Nature of the Structural Transformations of Li2MnO3 Following Electrochemical Cycling

Review—Multifunctional Materials for Enhanced Li-Ion Batteries Durability: A Brief Review of Practical Options

Surface phase diagram and stability of (001) and (111)LiMn2O4spinel oxides

Contact Info

Product

Resources

About

Surface Structure Evolution of LiMn₂O₄ Cathode Material upon Charge/Discharge

On the Localized Nature of the Structural Transformations of Li₂MnO₃ Following Electrochemical Cycling

On the Localized Nature of the Structural Transformations of Li₂MnO₃ Following Electrochemical Cycling