Lithium Incorporation Research Articles

Cycling Behavior of Thin Film LiAl Electrodes with Liquid and Solid Electrolytes

An Al foil was partially converted to by electrodeposition onto one side. The remaining unalloyed Al acted as a substrate for the film. Cycling was carried out with the film in contact with either the liquid propylene (PC) or the solid . After initial substantial capacity losses, coulombic efficiencies were 97 and 99% with the PC and PEO electrolytes, respectively. There was an additional loss with PEO (2 μA cm−2) due to a combination of oxygen and water vapor ingression and Li diffusion into the steel current collector. The loss in PC occurred during active operation, there being negligible loss on standing. Lithium incorporation into the film occurred readily due to the high diffusion coefficient of Li in . Stripping of the Li caused some cracking of the film as a result of the large molar volume change in forming from , but adhesion of the film to the Al substrate was strong. Literature values for the diffusion coefficient of Li in are low (10−16 and 10−22 cm2s−1 at 140° and 25°C, respectively), indicating that the growth of a few monolayers of the α phase on the surface of the could prevent further discharge. A model is proposed whereby the at the interface with the electrolyte becomes “super depleted” on discharge, but not enough to nucleate . Thus a diffusion gradient is set up in the film, causing the to grow from the α/β interface in a needle‐like morphology towards the electrolyte. Such a model is compatible with the substantial capacity losses during initial cycles.

Studies on the lithium and potassium uptake of nickel hydroxide electrodes

The extent of lithium and potassium uptake by bothα- andβ-Ni(OH)2 electrodes has been studied by atomic absorption/emission spectroscopy. It was found that lithium ions are preferentially taken up into the bulk of the electrodes. The increase in the end-of-charge potential on constant current charging in lithiated electrolyte compared with pure potassium hydroxide is attributed to the bulk incorporation of lithium into the Ni(OH)2 electrodes. X-ray studies have indicated no change in the phases present in the lithiated electrolytes either in the charged or discharged states. Cyclic voltametric measurements to 100 cycles showed no significant benefit due to lithium ions in terms of charge retention.

Lithium incorporation in the fibroblasts of manic-depressives

Lithium incorporation in cultured human skin fibroblasts was measured in a group of 10 manic-depressives and 10 controls. This system was believed to eliminate many of the sources of variability to which measurement of the lithium ratio in erythrocytes (RBCs) is subject. A fibroblast lithium ratio calculated from 1-hr lithium incorporation studies correlated highly with an in vitro RBC lithium ratio in medication-free controls. Manic-depressives and controls did not differ in lithium incorporation or fibroblast lithium ratio, leading to the conclusion that the lithium ratio is probably not a good measure for differentiating the two populations.

ChemInform Abstract: Phase Formation and Acoustic Emission During Electrochemical Incorporation of Lithium Into Aluminium from Molten LiCl‐KCl.

Abstract The formation of β-LiAl during electrochemical incorporation of lithium into aluminium from molten LiCl—KCl was investigated by chronoamperometric and acoustic emission techniques. The analysis of the potentiostatic current transients shows that the initial stages of formation of the phase β-LiAl may be described by an electrocrystallization model which includes instantaneous nucleation and three-dimensional growth controlled predominantly by the specific electrical conductivity of the electrolyte (the so-called ohmic control). It was found that upon electrochemical transformation of aluminium in β-LiAl a noticeable acoustic emission is generated which is strongly dependent on current density and time. The results of the acoustic emission measurements are interpreted in terms of the volume expansion which accompanies the transformation of aluminium into β-LiAl.

The secondary lithium—aluminium electrode at room temperature: II. Kinetics of the electrochemical formation of the lithium—aluminium alloy

The kinetics of the electrochemical formation of lithium—aluminium alloy was studied by voltammetric, potentiostatic, and pulse galvanostatic techniques in 1M LiClO 4—propylene carbonate solutions. It was established that the rate of formation of Li—Al alloy up to a thickness of 30 μm is controlled by the dynamics of the interaction between the two metals. The rate constant for this process was found to be a function of the applied potential with values between 10 −6 and 10 −7 cm/s. A diffusion coefficient of lithium into aluminium equal to 2.4 × 10 −11 cm 2/s was also determined from the initial decay of the potentiostatic transients. Values of the exchange current density ( i 0), 2.5 mA/cm 2 at 20 °C, and of the apparent activation energy (Δ H 0), 4.3 kcal/mol, for the process of lithium incorporation into the β-phase of lithium—aluminium were found from micropolarization measurements.

Phase formation and acoustic emission during electrochemical incorporation of lithium into aluminium from molten LiCl—KCl

The formation of β-LiAl during electrochemical incorporation of lithium into aluminium from molten LiCl—KCl was investigated by chronoamperometric and acoustic emission techniques. The analysis of the potentiostatic current transients shows that the initial stages of formation of the phase β-LiAl may be described by an electrocrystallization model which includes instantaneous nucleation and three-dimensional growth controlled predominantly by the specific electrical conductivity of the electrolyte (the so-called ohmic control). It was found that upon electrochemical transformation of aluminium in β-LiAl a noticeable acoustic emission is generated which is strongly dependent on current density and time. The results of the acoustic emission measurements are interpreted in terms of the volume expansion which accompanies the transformation of aluminium into β-LiAl.

Electrochemical behaviour of tungsten oxides in lithium-organic electrolyte cells

The electrochemical behaviour of various tungsten oxides in lithium-organic electrolyte cells has been studied by voltage-composition curves, micropolarization and cycling tests. The change in structure of the oxides which follows the lithium incorporation has been investigated by X-rays showing marked differences between WO 3, the typical crystallographic shear oxide W 20O 58, and the tunnel structure oxide W 18O 49.

Incorporation of lithium into gallium phosphide electrodes from lithium salt electrolytes in the presence of crown ethers

Anodic stripping analysis of cathodically polarized n- and p-type Gap electrodes has revealed that incorporation of lithium into a surface region of the electrodes takes place in aqueous electrolytes containing lithium salts and crown ethers such as 15-crown-5. Changes in spectral response of p-type electrodes caused by cathodic polarization in such electrolytes give support to the lithium incorporation. The redox potential for the incorporation reaction was estimated to lie somewhere between −1.95 and −0.91 V vs. SCE. The roles of crown ethers in the incorporation reaction are discussed.

Electrochemical lithium incorporation into WO 3 and MoO 3 thin films

The generally accepted mechanism of electrochromic phenomena into WO 3 thin films involves the simultaneous injection of cations and electrons to form a tungsten bronze M x WO 3, e.g. H x WO 3,Li x WO 3. Electrochromic cells of the type ITO MO 3/LiClO 4(M) in propylene carbonate/Pt, where M = W or MO and MO 3 is an amorphous thin film have been used. Different amounts of charges have been injected through these cells by electrochemical means at room temperature. The variations of the MO 3 electrode potential with the injected charge are in good agreement with the assumption of the formation of Li x MO 3 compounds. The free enthalpies of formation of these bronzes have been calculated. The behavior of thin film electrodes seems to be intermediate between amorphous and crystallized bulky materials. Some measurements of electrode potential have also been carried out with crystallized thin films of sputtered WO 3.

Lithium Incorporation by V 6 O 13 and Related Vanadium (+4, +5) Oxide Cathode Materials

The known vanadium oxides have been examined as cathode materials in ambient temperature nonaqueous secondary lithium cells. The discharge products have also been chemically prepared and characterized by x‐ray diffraction, thermal analysis, and magnetic susceptibility. The best cathode materials are and a slightly oxygen‐rich . Electrochemical and chemical preparations afford . The is described as an insertion compound of .

ESR study of lithium incorporation by V 2O 5 single crystals

Lithium has been chemically and electrochemically incorporated into V 2O 5 single crystals. The ESR spectra of these room temperature bronzes are characterized by the same g tensor as α-Li x V 2O 5 high temperature bronzes. This suggests that V 2O 5 acts as a three-dimensional framework host and that lithium is inserted into the channels of the orthorhombic structure. However, Li + ions are not randomly distributed into the lattice. A clustering of the paramagnetic centers surrounding these ions is observed, giving an exchange narrowed ESR signal. The usual 29 hyperfine line ESR spectrum of high temperature α-Li x V 2O 5 is again observed after heating the crystal above 300°C showing that these new bronzes convert to the previously reported Li x V 2O 5 bronzes.

Lithium incorporation in tungsten oxides

The incorporation, both electrochemically and chemically, of lithium at ambient temperatures into WO 3 has been studied. The phases formed, together with their lattice parameters, are compared to the known high temperature Li xWO 3 phases as well as to amorphous WO 3. The cubic phase was found to be extended to higher lithium contents, 0.67, at 25°C than at 650°C, 0.5; this is approaching the value 0.75 calculated from the crystal structure. In addition, a number of other tungsten oxides have been studied for their capability of incorporating lithium. A strong interrelationship of crystal structure and degree of lithium incorporation was also evident in these oxides.

Lithium incorporation by vanadium pentoxide

Lithium incorporation by vanadium pentoxide

Topochemical reactions of rutile related structures with lithium

The topochemical lithiation of rutile related MO 2 with n-BuLi, and in nonaqueous lithium electrochemical cells is reported. This series illustrates the importance of electronic conductivity and cell volume to substantial lithium incorporation. The Li xMO 2 compounds are metastable and decompose at temperatures less than 250°C.

Kinetics of Electrochemical Incorporation of Lithium into Aluminum

The electrochemical incorporation of lithium into aluminum was investigated by chronocoulometric, galvanostatic, and potentiostatic techniques. Results of the chronocoulometric measurements were interpreted in terms of the theory developed by Astakhov. Incorporation of lithium to form the solid solution α‐phase is limited by its rate of diffusion into aluminum, with a measured diffusion coefficient of about at 450°C. Implantation at potentials where a layer of intermetallic compound forms on the electrode surface was found to be limited initially by the reaction to form the compound (β‐phase) and subsequently by the rate of lithium diffusion into the growing β‐phase layer. The results of galvanostatic transient measurements indicate a diffusivity of lithium in of the order of 10−8 cm2/sec and a fast charge transfer step. The initial steps in the formation of the intermetallic compound appear to involve typical electrocrystallization (i.e., nucleation and growth) processes.

Synergetic effect of oxide catalysts with different dopents on catalytic activity: I. Nickel oxide and zinc oxide for carbon monoxide oxidation

The catalytic activity of pure, doped nickel oxide, and mixtures of nickel oxides with different dopents was investigated by the reaction of carbon monoxide oxidation. The incorporation of lithium ions in the oxide enhanced the activity and the addition of indium lowered the activity. The activity of mixtures increased to several times greater than would be predicted by simple additive effect of single doped catalysts. For zinc oxide, the incorporation of lithium or indium ions, respectively, decreased or increased the activity. Mixtures of zinc, oxides with different dopents were also more active than expected from the simple additive effect. The mechanism of the enhanced activity of mixtures was discussed from the viewpoint of synergetic action of doped catalysts with different Fermi levels.