Defect structure of β-LiAl

Kishio, K.; Brittain, J. O.

doi:10.1016/0022-3697(79)90121-5

Cited by 116 publications

(53 citation statements)

References 13 publications

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“…The XRD profile matches that of chemically synthesized β-LiAl (space group Fd-3m). 30 This is clearly the dominant crystalline phase, but vestiges of the aluminum metal peaks are present in Figure 2b. This is due to either incomplete lithiation of the Al or partial oxidation of the LiAl to lithium oxide and aluminum metal.…”

Section: Resultsmentioning

confidence: 94%

Size Effects in the Electrochemical Alloying and Cycling of Electrodeposited Aluminum with Lithium

Hudak

Huber

2012

J. Electrochem. Soc.

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The electrochemical alloying and cycling of electrodeposited aluminum films, electron-beam deposited aluminum films, and templatesynthesized aluminum nanorods with lithium is presented here. Electrodeposition of aluminum is performed at room temperature using ionic liquid solutions and is shown to exhibit high faradaic efficiency. To study the dependence of lithium-aluminum cycling on size, the thickness of these films is varied between 0.25 μm and 6.2 μm by varying the electrodeposition time. Electrochemical alloying and de-alloying of these films with lithium is observed in lithium half-cells at room temperature. The films reach theoretical capacity for the formation of LiAl (1 Ah g −1 ). The performance of electrodeposited aluminum films is dependent on film thickness, and the thinnest films exhibit the worst cycling behavior. Cycling of aluminum films formed by electron-beam deposition is in quantitative agreement with that of films formed by electrodeposition, and the two types of films have a similar appearance in SEM images taken after cycling. Synthesis of aluminum nanorod arrays on stainless steel substrates is also demonstrated using electrodeposition into anodic aluminum oxide templates followed by template dissolution. Unlike nanostructures of other lithium-alloying materials, the electrochemical performance of these aluminum nanorod arrays is worse than that of bulk aluminum.Lithium alloys have gained recent prominence as candidate materials for the negative electrode in lithium-ion batteries. 1 The advantage of lithium-alloy electrodes is their high theoretical capacity (two to ten times that of graphitic carbon), but they face major obstacles to commercialization because of poor cycling. The failure mechanism most often cited for lithium-alloy electrodes is fracture and pulverization of the active material due to large volume changes. Thus, nanostructured lithium-alloying electrodes have become a focus of research because materials with smaller dimensions can more easily accommodate the large strains. There is a continued need for fundamental understanding of size effects (micro to nano) in lithium-alloy electrodes, specifically the interdependence of particle size, spatial arrangement, and electrochemical behavior.Aluminum electrochemically alloys with lithium in organic electrolytes at room temperature 2, 3 but has been far less explored than silicon and tin. Electrochemical alloying of lithium and aluminum at room temperature produces only LiAl, 4 which has a theoretical capacity of 993 mAh g −1 . This is on par with that of Li 22 Sn 5 but significantly lower than that of Li 15 Si 4 , each of which undergoes at least three phase transitions to reach full lithiation. Aluminum has the advantage of only one phase transition during lithium insertion, resulting in a single, flat voltage profile. Thus, the LiAl anode may be simpler to characterize and more appropriate for fundamental studies of electrochemical alloying and size effects. Aluminum is also beneficial because of its low cost, wide availab...

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Section: Resultsmentioning

confidence: 94%

Size Effects in the Electrochemical Alloying and Cycling of Electrodeposited Aluminum with Lithium

Hudak

Huber

2012

J. Electrochem. Soc.

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“…Its lattice parameter has been determined by several researchers. [1][2][3][4] The structure of AlLi is composed of two sublattices, both Al and Li forming a diamond lattice and interpenetrating each other. If Li gives up its single valence electron and the charge is transferred from Li to more electronegative Al, Al has four electrons to form sp 3 bonds.…”

Section: Introductionmentioning

confidence: 99%

Elastic Constants of AlLi from First Principles

2005

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The elastic stiffness coefficients of single crystal AlLi with cubic NaTl (B32) structure were calculated at 0 K from the first principles. The obtained elastic stiffness coefficients, in units of GPa, were c 11 ¼ 66:9, c 12 ¼ 38:2 and c 44 ¼ 51:7. Then the bulk modulus, Young's modulus, shear modulus and Poison's ratio were estimated for polycrystalline AlLi from the elastic stiffness coefficients. The Young's modulus for single crystal AlLi was the highest in the h111i direction. The formation of the sp 3 -like bond connecting the nearest-neighbor Al atoms was confirmed from the charge density distribution. The elastic anisotropy of AlLi was compared with those of the sp 3 bonded semiconductors such as Si and GaAs.

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“…Different data can be found in the literature concerning the diffusion coefficient of lithium in Al-Li electrodes. The diffusion coefficient depends also strongly on the concentration of lithium in the Al-Li alloy [15,16]. [17].…”

Section: Lithium Deposition and Dissolution At Al Electrodesmentioning

confidence: 99%

Electrochemical investigation of Li–Al anodes in oligo(ethylene glycol) dimethyl ether/LiPF6

et al. 2010

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1 M LiPF 6 dissolved in oligo(ethylene glycol) dimethyl ether with a molecular weight 500 g mol -1 was investigated as a new electrolyte (OEGDME500, 1 M LiPF 6 ) for metal deposition and battery applications. At 25°C a conductivity of 0.48 9 10 -3 S cm -1 was obtained and at 85°C, 3.78 9 10 -3 S cm -1 . The apparent activation barrier for ionic transport was evaluated to be 30.7 kJ mol -1 . OEGDME500, 1 M LiPF 6 allows operating temperature above 100°C with very attractive conductivity. The electrolyte shows excellent performance at negative and positive potentials. With this investigation, we report experimental results obtained with aluminum electrodes using this electrolyte. At low current densities lithium ion reduction and re-oxidation can be achieved on aluminum electrodes at potentials about 280 mV more positive than on lithium electrodes. In situ X-ray diffraction measurements collected during electrochemical lithium deposition on aluminum electrodes show that the shift to positive potentials is due to the negative Gibbs free energy change of the Li-Al alloy formation reaction.

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Defect structure of β-LiAl

Cited by 116 publications

References 13 publications

Size Effects in the Electrochemical Alloying and Cycling of Electrodeposited Aluminum with Lithium

Size Effects in the Electrochemical Alloying and Cycling of Electrodeposited Aluminum with Lithium

Elastic Constants of AlLi from First Principles

Electrochemical investigation of Li–Al anodes in oligo(ethylene glycol) dimethyl ether/LiPF6

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