Correlating Capacity Fading and Structural Changes in Li[sub 1+y]Mn[sub 2−y]O[sub 4−δ] Spinel Cathode Materials: A Systematic Study on the Effects of Li/Mn Ratio and Oxygen Deficiency

Xia, Yongyao; Sakai, Tetsuo; Fujieda, Takuya; Yang, Xiao‐Qing; Sun, Xiaoming; F., Z.; McBreen, J.; Yoshio, Masaki

doi:10.1149/1.1376117

Cited by 220 publications

(136 citation statements)

References 27 publications

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“…The capacity fade could also be due to the loss of crystallinity during cycling due to formation of oxygen deficiencies, Jahn-Teller (JT) distortion etc. [13] - [15]. To increase our knowledge about the possible degradation mechanisms and subsequently attempt to modify and improve the performance of this material, it is essential to understand the reactions taking place on the electrode-electrolyte interface which in turn depends on stability, structure and composition of the reconstructed surface facets of the material.…”

Section: Introductionmentioning

confidence: 99%

Surface structure and equilibrium particle shape of the LiMn2O4spinel from first-principles calculations

2013

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First-principles density functional calculations were used to calculate surface properties of the LiMn 2 O 4 spinel. The calculations were benchmarked to obtain the correct semiconducting, JahnTeller distorted electronic ground state of bulk LiMn 2 O 4 and, using the same parameters, the predominant low-index polar surface facets (100), (110), and (111) were calculated to study their structure and stability. Following an investigation of possible surface terminations as well as surface layer reconstructions we find that the (111) LMO surface stabilizes through a targeted site-exchange of the under-coordinated surface Mn cations with fully coordinated tetrahedral sub-surface Li cations, effectively creating a partial inverse spinel arrangement at the surface.This reconstruction renders the (111) facet the most stable among the investigated facets. The equilibrium (Wulff) shape of a LiMn 2 O 4 particle was constructed and exhibits a cubo-octahedral shape with predominant (1 1 1) facets, in agreement with common experimental findings for the spinel structure.

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Section: Introductionmentioning

confidence: 99%

Surface structure and equilibrium particle shape of the LiMn2O4spinel from first-principles calculations

2013

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“…Properties such as these provide the foundation for the long-time performance and we cannot rationally design or optimize electrode materials without understanding how the electrochemical signature depends on the structure and chemistry. In this communication, we present first-principles energy calculations and a coupled cluster expansion model of the ionic ordering and its effect on the electrochemical behavior of Li x Ni 0.5 Mn 1.5 O 4 . In particular, the model confirms the significant effect of a preferred commensurate Li/vacancy ordering and Ni/Mn arrangement on the phase stability and resulting voltage profile.…”

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confidence: 99%

Revealing the coupled cation interactions behind the electrochemical profile of LixNi0.5Mn1.5O4

Lee

Persson

2012

Energy Environ. Sci.

114

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We present first-principles energy calculations and a cluster expansion model of the ionic ordering in Li x Ni 0.5 Mn 1.5 O 4 (0 ≤ x ≤ 1), one of the proposed highenergy density next-generation Li-ion cathode materials. The developed model predicts an intricate relationship between the preferred Li-vacancy ordering and the Ni/Mn configuration, which explains the difference in intermediate ground states between ordered (P4 3 32) and disordered (Fd3m) Ni/Mn configuration. The phase sequence as a function of lithiation as well as the voltage profile are well matched with experimental results. Understanding of the inherent chemical interactions and their impact on the performance of an energy storage material is essential when designing and optimizing Li-ion electrode materials.Li-ion batteries are poised to power the new generation of electric vehicles and thereby enable sustainable energy transportation. Among the most promising cathode materials, the lithium manganese spinel, LiMn 2 O 4 , has received attention due to its cheap price, non-toxicity, and good rate capability. 1,2 However, commercialization of LiMn 2 O 4 has been delayed due to capacity fade upon cycling, which has been attributed to the dissolution 3-5 of Mn 3+ produced by the redox process during lithiation/delithiation cycling. 6,7 Furthermore, it has been speculated that the strong Jahn-Teller distortion of the Mn 3+ ion degrades the structural stability of the material and inhibits Li migration. [8][9][10] Previous studies (see for example Ref. 3 and references therein) aimed at improving the cycling performance by substituting other transition metals into LiMn 2 O 4 suggest Li x Ni 0.5 Mn 1.5 O 4 as an attractive material.In Li x Ni 0.5 Mn 1.5 O 4 , the redox process occurs on the Ni site only, which prevents the creation of the Mn 3+ cation and its related problems. 11,12 Furthermore, the reduction of Ni 4+ to Ni 2+ occurs at 4.7 V, 3,11-15 which increases the total energy density of Li x Ni 0.5 Mn 1.5 O 4 as compared to LiMn 2 O 4 from 440 Wh/kg to 686 Wh/kg. 16 Despite the promising qualities of Li x Ni 0.5 Mn 1.5 O 4 for Liion battery applications, some of its fundamental properties have remained unexplained. For example, 1) the origin of the voltage step at Li 0.5 Ni 0.5 Mn 1.5 O 4 and its pronounced depen- * Corresponding author: eunseoklee@lbl.gov dence on the cation ordering, 11,17 2) the difference in rate capability, 11,18 and 3) the occurrence of reversible phase transitions between ordered and disordered Ni/Mn arrangement during charge/discharge cycling 1,19,20 are debated. Properties such as these provide the foundation for the long-time performance and we cannot rationally design or optimize electrode materials without understanding how the electrochemical signature depends on the structure and chemistry. In this communication, we present first-principles energy calculations and a coupled cluster expansion model of the ionic ordering and its effect on the electrochemical behavior of Li x Ni 0.5 Mn 1.5 O 4 . In particular, the mod...

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“…Several factors such as manganese dissolution, [3][4][5][6] formation of oxygen deficiency, 7 electrolyte decomposition, 8 Jahn-Teller distortion, 9 cation mixing between lithium and manganese, 10 and loss of crystallinity during cycling 11 have been reported to be responsible for the capacity fade.…”

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confidence: 99%

Surface/Chemically Modified LiMn[sub 2]O[sub 4] Cathodes for Lithium-Ion Batteries

Kannan

Manthiram

2002

Electrochem. Solid-State Lett.

146

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LiMn 2 O 4 spinel oxide has been surface/chemically modified with Li x CoO 2 , LiNi 0.5 Co 0.5 O 2 , Al 2 O 3 , and MgO using a chemical processing procedure followed by heat-treatment at 300-800°C. The surface/chemically modified samples show much better capacity retention at both 25 and 60°C than does the unmodified LiMn 2 O 4 ͑41% fade in 100 cycles at 60°C͒. Among the various compositions investigated, the LiNi 0.5 Co 0.5 O 2 -modified sample shows superior capacity retention with only 2.8% fade in 100 cycles at 60°C with around 110 mAh/g. The Al 2 O 3 -modified sample shows a higher capacity of 130 mAh/g, but with a faster fade ͑16% in 100 cycles at 60°C͒. The Li 0.75 CoO 2 -modified sample shows the best combination of capacity ͑124 mAh/g͒ and retention ͑8% fade in 100 cycles at 60°C͒. The modified samples also exhibit better capacity retention after aging at 55°C at 60-70% depth of discharge. is found to show excellent capacity retention with a capacity fade of Ͻ0.03% per cycle over 100 cycles at 60°C and C/2 rate. ExperimentalThe surface/chemical modification was accomplished by treating a commercially available LiMn 2 O 4 powder ͑Carus Chemical Company͒ with various amounts of the precursor solutions of Li x CoO 2 , LiCo 0.5 Ni 0.5 O 2 , Al 2 O 3 , or MgO through a chemical process so that the amount of the modifying material in the final product is 3-5 wt %.The modification with Li x CoO 2 and LiCo 0.5 Ni 0.5 O 2 involved a dissolution of the carbonates or acetates of the precursor metal ions in glacial acetic acid, refluxion of the mixture for about an hour, dispersion of the LiMn 2 O 4 spinel oxide in the precursor solution, evaporation of the solvent, and decomposition of the resultant product at around 400°C, followed by firing at 850°C in a flowing oxygen atmosphere for 12 h.The modifications with Al 2 O 3 and MgO involved the dispersion of the LiMn 2 O 4 spinel oxide in an aqueous solution of aluminum or magnesium nitrate, precipitation of hydrous aluminum or magnesium oxide over LiMn 2 O 4 particles through the addition of ammonium hydroxide, and heating the resultant product at 300 and 600°C, respectively, in air for 4 h.Cathodes were fabricated with the surface/chemically modified and unmodified LiMn 2 O 4 powder, Denka black carbon, and polytetrafluoroethylene ͑PTFE͒ binder in a weight ratio of 75:20:5. The electrochemical performances were evaluated with CR2032 coin cells assembled with the cathodes thus fabricated, metallic lithium anodes, polyethylene separators, and 1 M LiPF 6 in ethylene carbonate ͑EC͒ and diethyl carbonate ͑DEC͒ electrolyte between 3.5 and 4.3 V. Aging experiments were carried out as follows. After the first two cycles at a current density of 0.5 mA/cm 2 ͑C/2 rate͒, the coin cells were discharged to DOD ͑depth of discharge͒ values of 60 and 70% in the third cycle at room temperature. The cells were then subjected to aging at a constant temperature of 55°C for 100 h and the remaining capacity was determined by discharging the aged cells at room temperature to a cutoff vo...

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Correlating Capacity Fading and Structural Changes in Li[sub 1+y]Mn[sub 2−y]O[sub 4−δ] Spinel Cathode Materials: A Systematic Study on the Effects of Li/Mn Ratio and Oxygen Deficiency

Cited by 220 publications

References 27 publications

Surface structure and equilibrium particle shape of the LiMn2O4spinel from first-principles calculations

Surface structure and equilibrium particle shape of the LiMn2O4spinel from first-principles calculations

Revealing the coupled cation interactions behind the electrochemical profile of LixNi0.5Mn1.5O4

Surface/Chemically Modified LiMn[sub 2]O[sub 4] Cathodes for Lithium-Ion Batteries

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