Electronic and Bonding Properties of LiMn<sub>2</sub>O<sub>4</sub>Spinel with Different Surface Orientations and Doping Elements and Their Effects on Manganese Dissolution

Lee, Yoon Koo; Park, Jong‐Hyun; Lü, Wei

doi:10.1149/2.0991607jes

Cited by 37 publications

(32 citation statements)

References 51 publications

(99 reference statements)

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“…The states which shift above the Fermi level upon Li + removal are associated with Mn–O anti‐ or nonbonding states according to the pCOHP calculations (Figure b marked by *). The pCOHP calculations for bare LMO are in good agreement with previous work, showing the antibonding Mn–O nature of valence states directly below E f , whereas Mn–O bonding states occur at lower energies …”

Section: Resultssupporting

confidence: 89%

Operando Observations and First‐Principles Calculations of Reduced Lithium Insertion in Au‐Coated LiMn₂O₄

Bassett

Warburton

Deshpande

et al. 2019

Adv Materials Inter

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The deposition of protective coatings on the spinel LiMn2O4 (LMO) lithium‐ion battery cathode is effective in reducing Mn dissolution from the electrode surface. Although protective coatings positively affect LMO cycle life, much remains to be understood regarding the interface formed between these coatings and LMO. Using operando powder X‐ray diffraction with Rietveld refinement, it is shown that, in comparison to bare LMO, the lattice parameter of a model Au‐coated LMO cathode is significantly reduced upon relithiation. Less charge passes through Au‐coated LMO in comparison to bare LMO, suggesting that the reduced lattice parameter is associated with decreased Li+ solubility in the Au‐coated LMO. Density functional theory calculations show that a more Li+‐deficient near‐surface is thermodynamically favorable in the presence of the Au coating, which may further stabilize these cathodes through suppressing formation of the Jahn–Teller distorted Li2Mn2O4 phase at the surface. Electronic structure and chemical bonding analyses show enhanced hybridization between Au and LMO for delithiated surfaces leading to partial oxidation of Au upon delithiation. This study suggests that, in addition to transition metal dissolution from electrode surfaces, protective coating design must also balance potential energy effects induced by charge transfer at the electrode‐coating interface.

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Section: Resultssupporting

confidence: 89%

Operando Observations and First‐Principles Calculations of Reduced Lithium Insertion in Au‐Coated LiMn₂O₄

Bassett

Warburton

Deshpande

et al. 2019

Adv Materials Inter

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“…LMO structure has several possible orientations and terminations. [ 52 ] The (001) orientation has two possible planes, which consist of Li 2 termination and Mn 4 O 8 termination. The (110) orientation also has two possible planes which include MnO 2 termination and LiMnO 2 termination.…”

Section: Resultsmentioning

confidence: 99%

“…To identify the most stable configuration of several possible LMO surface orientations, the surface energy was calculated for 001_Li 2 , 110_MnO 2 , and 111_Mn, three different surface orientations of LMO structure. Surface energy is expressed as follows: [ 52,70 ]

σ = (E_{normalslab} - N E_{normalbulk}) / 2 A

where E slab is the total energy of a surface slab with a top and a bottom surface, E bulk is the bulk energy per formula unit, N is the number of chemical formula units in the slab, and A is the surface area of the slab.…”

Section: Methodsmentioning

confidence: 99%

“…[ 33,34,47–51 ] In literature, first‐principles simulations were carried out to study the Mn dissolution of LMO. [ 23,52,53 ] For the coating experiments, although the addition of an Al 2 O 3 coating layer presumably inhibited Mn dissolution, it was also found that excess Al 2 O 3 can sometimes act as an insulator and increase the charge transfer resistance, worsening the performance. [ 54 ] Moreover, various metal oxide coating layers have different influences on cycling performance and rate capability, while excessive ALD cycles can lead to lower rate capability for any metal oxide.…”

Section: Introductionmentioning

confidence: 99%

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Discovery of an Unexpected Metal Dissolution of Thin‐Coated Cathode Particles and Its Theoretical Explanation

Pham

Gao

et al. 2020

Advcd Theory and Sims

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The degree of metal dissolution of cathode materials is a critical parameter in determining the performance of lithium-ion batteries (LIBs). Ultra-thin coated cathode particles, fabricated via atomic layer deposition (ALD), exhibit superior battery performance over that of bare particles. Therefore, it is generally believed that a coating layer protects the particles from metal dissolution of active materials, which is a critical cathode degradation mechanism. However, it is observed that ultra-thin CeO 2 coating intensified the Mn dissolution of LiMn 2 O 4 (LMO) during cycling of LIBs, whereas ultra-thin Al 2 O 3 coating tended to inhibit Mn dissolution. A detailed density functional theory (DFT) study is carried out to explain these experimental observations by analyzing interaction of Mn atoms with neighboring electrode atoms in terms of energetic and structural aspect. All atomic and electronic analyses are consistent with the experimental observations. Several common materials are investigated as possible ALD coatings for LIBs to provide general insight, and it is found that Mn dissolution can be suppressed or accelerated depending on the material selection. This is the first report finding that depending on the coating material, metal dissolution can be accelerated, providing new insights into the impact of ALD coating materials on metal dissolution in cathode materials. potential, superior capacity, a long life cycle, and a sufficiently broad range of working temperatures. Although metal oxide cathodes satisfy the criteria, they suffer from an inevitable metal dissolution degradation process. In the dissolution degradation process, transition metal ions dissolve from cathode active materials and can deposit onto the anode, causing severe cell aging and irreversible side reactions that reduce performance. [1,2] For high performance cathode materials such as LiNi x Mn y Co z O 2 (NMC, x + y + z = 1), LiNi 0.5 Mn 1.5 O 4 (LNMO), and LiMn 2 O 4 (LMO), metal dissolution (Ni, Co, Mn, etc.) is severe, and, furthermore, it was found that in such cathode materials, which are composed of two or more transition metals, there is no preferential dissolution among the constituent metals. [3] To study the metal dissolution phenomena, manganese is an excellent candidate for intensive study of the fundamental interfacial processes and side reactions at cathode surfaces because of its low toxicity, low cost, and the high natural abundance of Mn, [4][5][6][7][8][9][10][11][12] which allows it to be used in several promising cathode materials, such as NMC, LNMO, and LMO. It has been published that Mn dissolution accounts for 23% and 34% of overall capacity degradation at room temperature and at 55°C [13] in LMO, respectively. The major reason for LMO degradation, [14][15][16][17][18] as well as for other metal oxide cathode materials, [3,[19][20][21] has been identified as structural changes in the material due to phase transformations, alternation of intrinsic properties (such as electronic and ionic conductivity), dissoluti...

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“…Given that different amounts of conductive additives, polymer binder, and active material result in different side reactions, such as transition metal dissolution or interfacial resistance, to accurately predict battery performance they should be included in the model. The current study aims to integrate the degradation phenomena of the cathode material with various ratios of the composite electrode constituents [1,[15][16][17][18]. By considering degradation mechanisms in addition to the key parameters of the composite electrode, the cycling performance of the battery cell can be predicted.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Active Material, Conductive Additives, and Binder in a Cathode Composite Electrode on Battery Performance

Lee¹

2019

Energies

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The current study investigated the effects of active material, conductive additives, and binder in a composite electrode on battery performance. In addition, the parameters related to cell performance as well as side reactions were integrated in an electrochemical model. In order to predict the cell performance, key parameters including manganese dissolution, electronic conductivity, and resistance were first measured through experiments. Experimental results determined that a higher ratio of polymer binder to conductive additives increased the interfacial resistance, and a higher ratio of conductive additives to polymer binder in the electrode resulted in an increase in dissolved transition metal ions from the LiMn2O4 composite electrode. By performing a degradation simulation with these parameters, battery capacity was predicted with various fractions of constituents in the composite electrode. The present study shows that by using this integrated prediction method, the optimal ratio of constituents for a particular cathode composite electrode can be specified that will maximize battery performance.

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Electronic and Bonding Properties of LiMn₂O₄Spinel with Different Surface Orientations and Doping Elements and Their Effects on Manganese Dissolution

Cited by 37 publications

References 51 publications

Operando Observations and First‐Principles Calculations of Reduced Lithium Insertion in Au‐Coated LiMn₂O₄

Operando Observations and First‐Principles Calculations of Reduced Lithium Insertion in Au‐Coated LiMn₂O₄

Discovery of an Unexpected Metal Dissolution of Thin‐Coated Cathode Particles and Its Theoretical Explanation

The Effect of Active Material, Conductive Additives, and Binder in a Cathode Composite Electrode on Battery Performance

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Electronic and Bonding Properties of LiMn2O4Spinel with Different Surface Orientations and Doping Elements and Their Effects on Manganese Dissolution

Cited by 37 publications

References 51 publications

Operando Observations and First‐Principles Calculations of Reduced Lithium Insertion in Au‐Coated LiMn2O4

Operando Observations and First‐Principles Calculations of Reduced Lithium Insertion in Au‐Coated LiMn2O4

Discovery of an Unexpected Metal Dissolution of Thin‐Coated Cathode Particles and Its Theoretical Explanation

The Effect of Active Material, Conductive Additives, and Binder in a Cathode Composite Electrode on Battery Performance

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Electronic and Bonding Properties of LiMn₂O₄Spinel with Different Surface Orientations and Doping Elements and Their Effects on Manganese Dissolution

Operando Observations and First‐Principles Calculations of Reduced Lithium Insertion in Au‐Coated LiMn₂O₄

Operando Observations and First‐Principles Calculations of Reduced Lithium Insertion in Au‐Coated LiMn₂O₄