New Insights into the Fundamental Chemical Nature of Ionic Liquid Film Formation on Magnesium Alloy Surfaces

Forsyth, Maria; Neil, Wayne; Howlett, Patrick C.; MacFarlane, Douglas R.; Hinton, Bruce; Rocher, Nathalie M.; Kemp, Thomas F.; Smith, Mark E.

doi:10.1021/am900023j

Cited by 83 publications

(97 citation statements)

References 31 publications

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“…47 However, other studies using ToF-SIMS revealed that both the cation and anion are present in the film although only the cation could be identified as a whole molecule. 26 This confirms that the anion reactivity plays a dominant role in the passivation of aluminium current collectors whilst the cation is somehow entrapped within the passive surface film.…”

Section: Sem and Edxs Studiesmentioning

confidence: 94%

Passivation behaviour of aluminium current collector in ionic liquid alkyl carbonate (hybrid) electrolytes

et al. 2018

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The compatibility of current collectors with the electrolyte plays a major role in the overall performance of lithium batteries, critical to obtain high storage capacity as well as excellent capacity retention. In lithium-ion batteries, in particular with cathodes that operate at high voltage such as lithium nickel cobalt manganese oxide, the cathodic current collector is aluminium and it is subjected to high oxidation potentials (>4 V vs. Li/Li + ). As a result, the composition of the electrolyte needs to be carefully designed in order to stabilise the battery performance as well as to protect the current collectors against corrosion. This study examines the role of a hybrid electrolyte composed of an ionic liquid (N-methyl-N-propyl pyrrolidinium bis(trifluoromethanesulfonyl)imide or Nmethyl-N-propyl pyrrolidinium bis(fluorosulfonyl)imide) and a conventional electrolyte mixture (LiPF 6 salt and alkyl carbonate solvents) with correlation to their electrochemical behaviour and corrosion inhibition efficiency. The hybrid electrolyte was tested against battery grade aluminium current collectors electrochemically in a three-electrode cell configuration and the treated aluminium surface was characterised by SEM/EDXS, optical profilometry, FTIR, and XPS analysis. Based on the experimental results, the hybrid electrolytes allow an effective and improved passivation of aluminium and lower the extent of aluminium dissolution in comparison with the conventional lithium battery electrolytes and the neat ionic liquids at high anodic potentials (4.7 V vs. Li/Li + ). The mechanism of passivation behaviour is also further investigated. These observations provide a potential direction for developing improved hybrid electrolytes, based on ionic liquids, for higher energy density devices.npj Materials Degradation (2018) 2:13 ;

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Section: Sem and Edxs Studiesmentioning

confidence: 94%

Passivation behaviour of aluminium current collector in ionic liquid alkyl carbonate (hybrid) electrolytes

et al. 2018

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“…As in the cases of Mg and AZ31, the ZE41 surface showed no change in appearance following exposure to the ionic liquid; however, unlike those cases, where samples subjected to long-term exposure led to thick deposits, visible via SEM analysis, SEM analysis of the ZE41 substrate showed no features indicative of film formation [81]. Conversely, EIS obtained during a 24-h treatment of the ZE41 coupon revealed rapid buildup of a resistive component on the surface, during which time the OCP showed extensive noise, indicative of an ongoing electrochemical process likely occurring on the surface, both indicating likely film formation.…”

Section: Fluoride Conversion Treatment [Bis(trifluoromethanesulfonyl)mentioning

confidence: 78%

“…Another pretreatment option lies in the replacement of the oxide/hydroxide layer either as a companion for, or substitute to, further deposition. The continued research into batteries, especially lithium batteries [77,78], has produced several new insights into the potential of ionic liquids, including their use as a surface conversion treatment on magnesium [79][80][81], and research into the lubrication properties of ionic liquids in wear minimization have found that the same ILs are also able to produce beneficial tribological surface layers, in part due to their dipolar structure, in aluminum-steel interfaces [82][83][84][85].…”

Section: Ionic Liquids and Surface Treatmentsmentioning

confidence: 99%

“…Studies by Howlett, MacFarlane, Forsyth, et al [79][80][81] have demonstrated that the bis(trifluoromethanesulfonyl)amide anion [(Tf) 2 N À -(II) or (CF 3 SO 2 ) 2 N À ] can react with reactive metallic substrates, such as lithium [77,78], to provide electrochemically desirable surface layers. Although normally stable to reduction, the TFSA anion is prone to reductive decomposition of approximately À2.0 V (vs. Fc/Fc þ ), particularly in the presence of water and/or O 2 [95], well before the reported cathodic limit of many ionic liquids, leading to the formation of LiF on the metallic surface along with other fluorine-containing species [77,78,95].…”

Section: Fluoride Conversion Treatment [Bis(trifluoromethanesulfonyl)mentioning

confidence: 99%

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Ionic Liquid Treatments for Enhanced Corrosion Resistance of Magnesium‐Based Substrates

Petro

Schlesinger

Song³

2010

Modern Electroplating

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SONG INTRODUCTIONMagnesium (Mg) is the eighth most abundant element on earth, possessing several advantageous properties including a high strength to weight ratio and one of the lightest metals with a density that is only two-thirds that of aluminum and one-fourth that of iron at 1.74 g cm À3 . Additional properties that contribute to magnesium's versatility in the automotive, electronic, and aerospace industries include a high thermal conductivity, high dimensional stability, good electromagnetic shielding characteristics, high damping characteristics, good machinability, and easy recyclability [1]. These properties make the utilization of magnesium of particular interest to the automotive and aerospace industries where the weight reduction provides a simple means to achieve higher fuel efficiencies without sacrificing structural strength.Despite its many valuable properties, magnesium remains a very reactive element, prone to a number of undesirable properties, including poor corrosion and wear resistance, poor creep resistance, and high chemical reactivity, which have limited its wider industrial use. As such, automobiles currently possess few magnesium cast parts, averaging only a few pounds per car. Pure magnesium corrodes rapidly in humid atmospheric and/or aqueous environments where anions such as Cl À , Br À , I À , and SO À x promote local and generalized corrosion [2][3][4][5][6][7][8][9][10][11][12]. Compounds like alcohols, ethers, and phenols also attack magnesium [13]. Although alloying magnesium with elements such as manganese, aluminum, zinc, zirconium, and rare earths [14,15] can improve its properties, magnesium and its alloys continue to be extremely susceptible to galvanic corrosion, which can cause severe pitting in the metal, resulting in decreased mechanical stability and an unattractive appearance of the surface. Although uniform attack [16][17][18] is generally the most prevalent form of electrochemical corrosion, occurring with equal intensity over the entire surface of the metal, in the case of magnesium, especially pure magnesium, the partially protective surface film makes localized galvanic [19][20][21][22][23][24] and pitting corrosion [25-35] more common and worrisome, largely due to the difficulty in their detection and suppression. Galvanic corrosion occurs when two metals/alloys having differing compositions, and thus standard electrode potentials, are electrically coupled in the presence of an electrolyte. This coupling results in the formation of a galvanic cell, which preferentially corrodes the more reactive, or electronegative, of the two metals. Since magnesium has a highly negative standard electrode potential (E 0 ¼À2.37 V) there are few metal couples with which serious and rapid corrosion does not occur. Pitting corrosion, defined by the formation of small pits on the surface of a metal/alloy, usually stem from galvanic corrosion of a surface defect and progresses similar to crevice corrosion, where stagnant liquid in a crevice begins oxidizing the metal and/or its pass...

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“…Phosphorus-containing ionic liquids have been extensively applied in corrosion protection of magnesium alloys [55][56][57][58][59][60][61][62][63][64]. Together with corrosion, another major cause of surface failure of magnesium alloys is their poor tribological performance.…”

Section: Introductionmentioning

confidence: 99%

Halogen-Free Phosphonate Ionic Liquids as Precursors of Abrasion Resistant Surface Layers on AZ31B Magnesium Alloy

2015

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Surface coatings formed by immersion in the ionic liquids (ILs) 1,3-dimethylimidazolium methylphosphonate (LMP101), 1-ethyl-3-methylimidazolium methylphosphonate (LMP102) and 1-ethyl-3-methylimidazolium ethylphosphonate (LEP102) on magnesium alloy AZ31B at 50 °C have been studied. The purpose of increasing the temperature was to reduce the immersion time, from 14 days at room temperature, to 48 hours at 50 °C. The abrasion resistance of the coated alloy was studied by microscratching under progressively increasing load, and compared with that of the uncoated material. The order of abrasion resistance as a function of the IL is LEP102 > LMP101 > LMP102, which is in agreement with the order obtained for the coatings grown at room temperature. The maximum reduction in penetration depth with respect to the uncovered alloy, of a 44.5%, is obtained for the sample treated with the ethylphosphonate LEP102. However, this reduction is lower than that obtained when the coating is grown at room temperature. This is attributed to the increased thickness and lower adhesion of the coatings obtained at 50 °C, particularly those obtained from methylphosphonate ionic liquids. The results are discussed from SEM-EDX and profilometry.

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New Insights into the Fundamental Chemical Nature of Ionic Liquid Film Formation on Magnesium Alloy Surfaces

Cited by 83 publications

References 31 publications

Passivation behaviour of aluminium current collector in ionic liquid alkyl carbonate (hybrid) electrolytes

Passivation behaviour of aluminium current collector in ionic liquid alkyl carbonate (hybrid) electrolytes

Ionic Liquid Treatments for Enhanced Corrosion Resistance of Magnesium‐Based Substrates

Halogen-Free Phosphonate Ionic Liquids as Precursors of Abrasion Resistant Surface Layers on AZ31B Magnesium Alloy

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