Li2 CO Research Articles

Structural characterization of layered LiNi 0.85− xMn xCo 0.15O 2 with x = 0, 0.1, 0.2 and 0.4 oxide electrodes for Li batteries

We report the synthesis of LiNi 0.85− x Co 0.15Mn x O 2 positive electrode materials from Ni 0.85− x Co 0.15Mn x (OH) 2 and Li 2CO 3. XRD and XPS are used to study the effect of Mn-doping on the microstructures and oxidation states of the LiNi 0.85− x Co 0.15Mn x O 2 materials. The analysis shows that Mn-doping promotes the formation of a single phase. With increasing substitution of Mn ions for Ni ions, the lattice parameter a decreases, while the lattice parameters c and c/ a increase. XPS revealed that the oxidation states of Ni, Co and Mn in LiNi 0.85− x Co 0.15Mn x O 2 compounds (where x = 0.1, 0.2 and 0.4) were +2/+3, +3 and +4. The substitution of Mn ions for Ni ions induces a decrease in the average oxidation state of Ni. Because the substitution of Mn for Ni ions is complex, the extent of the changes between the lattice parameter and L M–O differ. The occupation of Ni in Li sites is affected by the ordering of Mn 4+ with Ni 2+ and Mn 4+ with Li +.

Synthesis powder precursor of LAS ceramics via pH controlled wet chemical process

A powder precursor of β-spodumene based LAS ceramics was synthesized by sol–gel process and precipitation method using Li 2CO 3, Al 2SO 4 and sol of SiO 2 in dilute solution of H 2SO 4. The wet chemical pH controlled methods used for synthesis of LAS ceramic's precursor are able to prevent the extremely low acidity of gel. These techniques provide an interesting option for preparation of LAS ceramics because the produced amount of corrosive gases during the thermal treatment (calcination) of precursor is reduced. Thermal analysis methods (simultaneous TG-DTA), infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for investigation of precursor composition and properties.

Electrochemical performance of LiFePO 4/C synthesized by solid state reaction using different lithium and iron sources

LiFePO 4/C cathode materials were prepared from different lithium and iron sources, using glucose as the carbon source and the reducing agent, via a solid state reaction. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), galvanostatic charge–discharge test and cyclic voltammetry (CV). The results showed that the LiFePO 4/C is olivine-type phase, and composed of relatively large particles of about 400 nm and some nano-sized particles, which favor the electronic conductivity. The LiFePO 4/C cathode material synthesized from Li 2CO 3 and Fe 2O 3 had the smallest particles and the highest uniformity. It delivered the capacity of 145.8 mA h/g at 0.2 C, and had good reversibility and high capacity retention. The precursor of LiFePO 4/C was characterized by thermogravimetry (TG) to discuss the crystallization formation mechanism of LiFePO 4.

Sorption properties of lithium carbonate doped CaO and its performance in sorption enhanced methane reforming

In-house prepared lithium carbonate doped CaO was tested for its CO 2 sorption properties and suitability as a CO 2 sorbent for sorption-enhanced reforming of methane. The new material demonstrated CO 2 capacity at the temperatures above the equilibrium for CaO recarbonation reaction. However, the capacity was unstable and decreased during carbonation–regeneration cycles. After sufficiently large number of cycles Li dopant escaped from the sorbent and its sorption behavior resembled to that of CaO. The main route of escape is, probably, a crossover of liquid Li 2CO 3 onto crucible in TG experiments and onto catalyst in SER tests. Sorption enhanced methane reforming at 2 bar pressure, 750 °C and H 2O to CH 4 ratio of 4 using novel sorbent yielded as high as 99.8 vol% pure hydrogen during the first cycle. In subsequent cycles the hydrogen purity drastically decreased as a result of severe catalyst poisoning by Li.

Synthesis, crystal structure and optical properties of Li 2Cu 5(PO 4) 4

The single crystals of Li 2Cu 5(PO 4) 4 have been grown in the Li 2CO 3–H 3BO 3 borate fluxes. Li 2Cu 5(PO 4) 4 crystallizes in the centrosymmetric triclinic space group P-1 with a = 6.03580(10) Å, b = 9.2211(2) Å, c = 11.4138(2) Å, α = 75.5750(10)°, β = 80.2540(10)°, γ= 74.1590(10)°, Z = 2. The three-dimensional framework is built up of LiO 5, CuO 4, Cu/LiO 5 polyhedra and isolated PO 4 tetrahedra. The IR spectrum and UV–Vis–NIR diffuse reflectance spectrum of Li 2Cu 5(PO 4) 4 have been studied.

Solubilization of SEI lithium salts in alkylcarbonate solvents

The SEI (Solid Electrolyte Interphase) at the surface of electrodes in lithium-ion batteries is composed of various lithium compounds, organic or mineral, which have a direct impact on cycling performance. The main lithium species constituting the SEI and selected in this study are lithium fluoride LiF, lithium carbonate Li 2CO 3, lithium hydroxide LiOH, lithium oxide Li 2O, lithium methoxide LiOCH 3 and lithium ethoxide LiOC 2H 5. Their solubilities were determined in ethylene, propylene, dimethyl, diethyl and vinylene carbonates (EC, PC, DMC, DEC and VC) and in one of their mixtures commonly used in lithium-ion batteries (EC/PC/3DMC) by mean of atomic absorption spectroscopy (AAS). These solutions were also investigated by EIS (Electrochemical Impedance Spectroscopy) and conductimetry measurements. Results show that while solubilization properties differ between LiF and other lithium compounds considered, their association pattern in solution is identical and solutions are mainly constituted of quadrupolar aggregates.

Reinvestigation of the synthesis of LiFeVO 4

The synthesis of LiFeVO 4 composition has been performed in air starting from Li 2CO 3, Fe 2O 3, and V 2O 5 and using the standard solid-state reaction route reported by Refs. [13–15]. Identical X-ray diffraction pattern has been obtained, however our careful analysis with MDI Jade 5.0 software does not agree with previously reported pure LiFeVO 4 samples. The powder pattern has been perfectly indexed using the single crystal data of LiVO 3 ( C2/ c, a = 10.16718 Å, b = 8.415725 Å, c = 5.884155 Å and β = 110.489°) and α-Fe 2O 3 ( R-3 c, a = 5.035 Å, c = 13.75 Å).

The competitive ionic conductivities in functional composite electrolytes based on the series of M-NLCO (M = Ce 0.8Sm 0.2O 2-δ, Ce 0.8Gd 0.2O 2-δ, Ce 0.8Y 0.2O 2-δ; NLCO = 0.53Li 2CO 3–0.47Na 2CO 3)

In order to identify competitive ion-conducting materials in ceria-carbonates composite electrolytes, M-NLCO (M = Ce 0.8Sm 0.2O 2-δ (SDC), Ce 0.8Gd 0.2O 2-δ (GDC), Ce 0.8Y 0.2O 2-δ (YDC); NLCO = 0.53Li 2CO 3–0.47Na 2CO 3) sintered at different temperatures (600° C, 625° C, 650° C, 675° C and 700° C) have been prepared and characterized. It is found that independent of systems, the 675° C-sintered composites in M-NLCO always present the highest conductivities because of the best NLCO distribution and interfacial microstructures. Moreover, among three composites (sintered at 675° C), the total ( σ t ) and grain boundary ( σ g b ) conductivities measured at 600° C are ranked as: SDC-NLCO ( σ t − SDC - NLCO 600 ° C = 9.1 × 10 − 2 Scm − 1 , σ g b − SDC - NLCO 600 ° C = 28.1 × 10 − 2 Scm − 1 ) ﹥ GDC-NLCO ( σ t − GDC - NLCO 600 ° C = 5.8 × 10 − 2 Scm − 1 , σ g b − GDC - NLCO 600 ° C = 18.9 × 10 − 2 Scm − 1 ) ﹥ YDC-NLCO ( σ t − YDC - NLCO 600 ° C = 3.1 × 10 − 2 Scm − 1 , σ g b − YDC - NLCO 600 ° C = 12.6 × 10 − 2 Scm − 1 ), which is attributed to ionic-radius compatibility between the dopant and the host as well as the NLCO distribution and interfacial microstructures. It can be concluded that ionic-radius compatibility between the dopant and the host, NLCO distribution and interfacial microstructures have important effects on improving ionic conductivities for ceria-carbonates composite electrolytes.

Synthesis and electrochemical properties of Li 4Ti 5O 12

The spinel compound Li 4Ti 5O 12 was synthesized by a solid state method. In this synthesizing process, anatase TiO 2 and Li 2CO 3 were used as reactants. The influences of reaction temperature and calcination time on the properties of products were studied. When calcination temperature was 750 °C and calcination temperature was 24 h, the products exhibited good electrochemical properties. Its discharge capacity reached 160 mAh g −1 and its capacity retention was 97% at the 50th cycle when the current rate was 1 C. When current rate increased to 10 C, its first discharge capacity could reach 136 mAh g −1, and its capacity retention was 85% at the 50th cycle.

The effect of lithium addition on aluminum-reinforced α-LiAlO 2 matrices for molten carbonate fuel cells

The effect of lithium hydroxide (LiOH) addition as a lithium source is discussed as a way to prevent Li-ion shortages in aluminum-based α-LiAlO 2 matrices of molten carbonate fuel cells. Our results show that the use of LiOH as a lithium source to prevent a Li-ion shortage caused by a lithiated Al-reaction during the operation of the cell allows for more stable performance and greater durability than when lithium carbonate (Li 2CO 3) is used as the lithium source. The behavior of high-lithium content mixtures is attributed to the presence of reactive aluminum particles, which promote the formation of lithium aluminate (LiAlO 2) phases at 650 °C. The incorporation of low-melting-point lithium and an efficient pathway to the aluminum in a reinforced matrix has improved the in-situ mechanical strength via the lithiated Al-reaction, and they do not lead to any noticeable loss in cell performance, even after 4000 h of operation. From the post-test results, the cell with LiOH stored in the cathode channel shows effective formation of the stable crystalline phase of α-LiAlO 2 and enhancement of the mechanical strength during cell operation.

Novel methods of tritium production rate measurements in HCLL TBM mock-up experiment with liquid scintillation technique

Two novel methods of tritium production rate (TPR) measurements applied in HCLL TBM mock-up neutronic experiment are described and discussed. In the first method LiF TLD detectors used for gamma radiation dose measurements are applied as detectors of −β decay of tritium (T) produced by neutrons. TL signal expressed as mGy/h is proportional to energy accumulated in self-irradiation process (SI). However, the TL signal is proportional to tritium activity generated in detector material, recalculation to Bq/mg requires calibration by independent measurement of T activity in the TLD. In our experiments determination of this activity was performed by LSC technique. Good correlation between the 3H activity and TLD signal was observed. The second presented method is based on direct measurement of T in LiPb material with the use of LSC spectrometer. Dissolution of LiPb in nitric acid, and than composing aliquot containing well known mass of irradiated LiPb mixed than with scintillation cocktail, is measured in LS spectrometer providing signal proportional to the T activity. It was proved by series of experiments that procedure performed at controlled conditions ensures no loss of tritium while preparation. Optimization measurement conditions with respect of type of the scintillator used and composition of aliquot/scintillator mixture provide counting efficiency above 22%. Sample material for testing the both techniques was irradiated by neutron flux either at nuclear research reactor “Maria”, Świerk, Poland or at the Frascati Neutron Generator Laboratory in HCLL TBM neutronic experiment. Li 2CO 3 pellets used as reference were irradiated in the same experiment with TLDs, and samples of LiPb-eutectic and then analysed by modified Dierckx method, a well established technique. Measurement results obtained applying the both techniques described above as well as the control Li 2CO 3 pellets were in very good consistency. Direct measurements of T produced in LiPb at different depth in HCLL TBM mockup agrees well with MCNP simulation results. Parameters of the simulation provide additionally information on 6Li abundance and Li content in the LiPb mixture. Spread of the T activity observed at the same depth for different samples correspond with inhomogeneity of the eutectic composition investigated and reported. Direct measurement of T activity seems to be the very promising and relatively simple method of validation of neutronic codes and nuclear data capabilities for calculation TPR in fusion relevant materials provided parameters of the irradiated material are well known.

Effects of calcination temperature on properties of Li 2SiO 3 for precursor of Li 2FeSiO 4

Li 2SiO 3 was synthesized by combination of sol-gel method and calcination at high temperature using Li 2CO 3, HNO 3, Si(OC 2H 5) 4 and C 2H 5OH as starting materials. The effects of calcination temperature and refluxing system on the composition and properties of lithium silicate were investigated. The samples were characterized by TGA/DTA, XRD, SEM and particle size analysis. Li 2FeSiO 4 was prepared by the solid-state reaction between Li 2SiO 3 and FeC 2O 4·2H 2O. The XRD patterns show that the use of refluxing system in the sol-gel preparation can decrease the Li 2Si 2O 5 and Li 4SiO 4 impurities in the Li 2SiO 3 sample. The calcination temperature plays an important role in the properties of the Li 2SiO 3 samples. The sample calcined at 700 °C has high purity of 97% Li 2SiO 3 and good morphology as precursor of Li 2FeSiO 4. It consists of primary particles with size of 1–3 μm, and the primary particle clusters form agglomerates with loose and porous appearance.

Investigation of the rechargeability of Li–O 2 batteries in non-aqueous electrolyte

To understand the limited cycle life performance and poor energy efficiency associated with rechargeable lithium–oxygen (Li–O 2) batteries, the discharge products of primary Li–O 2 cells at different depths of discharge (DOD) were systematically analyzed using XRD, FTIR and Ultra-high field MAS NMR. When discharged to 2.0 V, the reaction products of Li–O 2 cells include a small amount of Li 2O 2 along with Li 2CO 3 and RO–(C O)–OLi in the alkyl carbonate-based electrolyte. However, regardless of the DOD, there is no Li 2O detected in the discharge products in the alkyl-carbonate electrolyte. For the first time it was revealed that in an oxygen atmosphere the high surface area carbon significantly reduces the electrochemical operation window of the electrolyte, and leads to plating of insoluble Li salts on the electrode at the end of the charging process. Therefore, the impedance of the Li–O 2 cell continues to increase after each discharge and recharge process. After only a few cycles, the carbon air electrode is completely insulated by the accumulated Li salt terminating the cycling.

Glass-ceramics based on spodumene–enstatite system from natural raw materials

Glasses of compositions (wt%) corresponding to 50–90 spodumene and 50–10 enstatite were prepared depending on natural raw materials and Li 2CO 3 as small ingredient. The crystallization behavior was studied using DTA and XRD. The effect of addition of the nucleating agents (LiF) to a selected glass was also examined. Polarizing microscope and dilatometeric techniques were used to study the microstructures and the thermal expansion coefficient, respectively. XRD showed that the crystalline materials are mainly enstatite, clinoenstatite, β-eucryptite ss and β-spodumene ss. The shift of the glass composition to that of enstatite results in increased bulk crystallization. The presence of LiF does not greatly affect the mineral assemblages yet it improves the thermal expansion coefficients (TEC) of the crystalline samples and promotes the initial crystallization. Low and even negative values, ranging from −5.91 × 10 −7/K to 2.48 × 10 −7/K in the temperature range 293–573 K and 300–737 K, respectively, could be obtained, which make such materials applicable for thermally stable articles.

Gadolinia-doped ceria mixed with alkali carbonates for solid oxide fuel cell applications: I. A thermal, structural and morphological insight

Ceria-based composites are developed and considered as potential electrolytes for intermediate solid oxide fuel cell applications (ITSOFC). After giving a survey of the most relevant results in the literature, the structural, thermal and morphological properties of composite materials based on gadolinia-doped ceria (GDC) and alkali carbonates (Li 2CO 3–K 2CO 3 or Li 2CO 3–Na 2CO 3) are carefully examined. Thermal analyses demonstrate the stability of the composite with very low weight losses of both water and CO 2 during thermal cycling and after 168 h ageing. High-temperature and room-temperature X-ray diffraction allowed determining the precise structure of the composite and its regular and reversible evolution with the temperature. The microstructure and morphology of electrolyte pellets, as observed by scanning electron microscopy (SEM), show two-well separated phases: nanocrystals of GDC and a well-distributed carbonate phase. Finally, electrical conductivity determined by impedance spectroscopy is presented as a function of time to highlight the stability of such composites over 1500 h.

High temperature capture of CO 2 on lithium-based sorbents from rice husk ash

Highly efficient Li 4SiO 4 (lithium orthosilicate)-based sorbents for CO 2 capture at high temperature, was developed using waste materials (rice husk ash). Two treated rice husk ash (RHA) samples (RHA1 and RHA2) were prepared and calcined at 800 °C in the presence of Li 2CO 3. Pure Li 4SiO 4 and RHA-based sorbents were characterized by X-ray fluorescence, X-ray diffraction, scanning electron microscopy, nitrogen adsorption, and thermogravimetry. CO 2 sorption was tested through 15 carbonation/calcination cycles in a fixed bed reactor. The metals of RHA were doped with Li 4SiO 4 resulting to inhibited growth of the particles and increased pore volume and surface area. Thermal analyses indicated a much better CO 2 absorption in Li 4SiO 4-based sorbent prepared from RHA1 (higher metal content sample) because the activation energies for the chemisorption process and diffusion process were smaller than that of pure Li 4SiO 4. RHA1-based sorbent also maintained higher capacities during the multiple cycles.

A study of binary iron/lithium organometallic complexes as single source precursors to solid state cathode materials for potential Li ion battery application

Solid state and solution phase decomposition of organometallic half sandwich and sandwich complexes of type [CpFeCODLi × DME] 1, [CpFeCODLi × TMEDA] 2 and [(Cp) 2FeLi 2 × 2 TMEDA] 3 (Cp = cyclopentadienyl, COD = 1,5-cyclooctadiene, DME = dimethoxyethane, TMEDA = tetramethylethylenediamine) derived from ferrocene, yield different kinds of lithium ferrites under oxidative and inert conditions. Thermogravimetry (TG) and TG coupled mass spectrometry of these compounds indicate that the decomposition begins above 170 °C for 1, 185 °C for 2 and 190 °C for 3 with removal of all the organic ligands. In the absence of oxygen, compounds 1, 2 and 3 decompose to a mixture of Fe, Fe 3C and Li 2O/Li 2CO 3 at temperatures above 200 °C. Amorphous α-LiFeO 2 is formed in the temperature range of 200–400 °C in the presence of oxygen. Crystalline α-LiFeO 2 is formed only above 400 °C using 1. Elemental analysis of the LiFeO 2 obtained from 1 indicates a drastic decrease in the carbon and hydrogen content with the increase in the oxidation temperature. XRD reveals the presence of Li 2CO 3 as second phase formed for precursors 1, 2, and 3 under oxidative conditions. Solution phase decomposition of 2 and 3 in the absence of oxygen followed by annealing at 600 °C yields Li 2Fe 3O 5, Li 5FeO 4 and Fe 3C depending on the solvent to precursor ratio in contrast to the α-LiFeO 2 phase formed under pure solid state decomposition conditions. However, all lithium ferrites (Li 2Fe 3O 5, Li 5FeO 4) are converted to α-LiFeO 2 when oxidized above 500 °C. The α-LiFeO 2 products were further characterized by IR, XPS, and TEM. Electrochemical analysis of the α-LiFeO 2 was performed, showing a moderate initial capacity of 13 mAh/g.

Hydrogen trapping and luminescence characteristic in ion-implanted Li 2TiO 3 and Li 2ZrO 3

Hydrogen trapping and its interaction with defects in Li 2TiO 3 and Li 2ZrO 3 that were irradiated with hydrogen isotopes and exposed to air were investigated using ion beam techniques and photo-stimulated luminescence (PSL) measurements. During irradiation with 10 keV H 2 +, the incident hydrogen was trapped in Li 2TiO 3 at the end of its trajectory until the local concentration reached 12.5 at.%, whereas an increase in the hydrogen retained in Li 2ZrO 3 was observed at a considerably greater depth as compared to the projected range. A broad PSL emission with two peaks at around 2.8 and 3.1 eV was observed under irradiation of Li 2ZrO 3 with 5.17 eV light. The PSL intensity of the band at 2.8 eV showed a remarkable decrease as compared to the peak at 3.1 eV upon irradiation with 10 keV D 2 +. The results of isochronal annealing subsequent to irradiation showed that the recovery of the luminescence intensity in the 2.8 eV luminescent centers and release of hydrogen occurred in the same temperature range of 350–450 K. In addition, the formation of a Li 2CO 3 layer at the surface of Li 2TiO 3 and Li 2ZrO 3 following exposure to air was subject to the humidity conditions and was considered to play an important role in the dissociation of water vapor and hydrogen trapping beneath the reaction layer in Li 2TiO 3 and Li 2ZrO 3.

High power performance of nano-LiFePO 4/C cathode material synthesized via lauric acid-assisted solid-state reaction

A nano-LiFePO 4/C composite has been directly synthesized from micrometer-sized Li 2CO 3, NH 4H 2PO 4, and FeC 2O 4·2H 2O by the lauric acid-assisted solid-state reaction method. The SEM and TEM observations demonstrate that the synthesized nano-LiFePO 4/C composite has well-dispersed particles with a size of about 100–200 nm and an in situ carbon layer with thickness of about 2 nm. The prepared nano-LiFePO 4/C composite has superior rate capability, delivering a discharge capacity of 141.2 mAh g −1 at 5 °C, 130.9 mAh g −1 at 10 C, 121.7 mAh g −1 at 20 °C, and 112.4 mAh g −1 at 30 °C. At −20 °C, this cathode material still exhibits good rate capability with a discharge capacity of 91.9 mAh g −1 at 1 °C. The nano-LiFePO 4/C composite also shows excellent cycling ability with good capacity retention, up to 100 cycles at a high current density of 30 °C. Furthermore, the effect of lauric acid in the preparation of nano-LiFePO 4/C composite was investigated by comparing it with that of citric acid. The SEM images reveal that the morphology of the LiFePO 4/C composite transformed from the porous structure to fine particles as the molar ratio of lauric acid/citric acid increased.

Investigation on the charging process of Li 2O 2-based air electrodes in Li–O 2 batteries with organic carbonate electrolytes

The charging process of Li 2O 2-based air electrodes in Li–O 2 batteries with organic carbonate electrolytes was investigated using in situ gas chromatography/mass spectroscopy (GC/MS) to analyze gas evolution. A mixture of Li 2O 2/Fe 3O 4/Super P carbon/polyvinylidene fluoride (PVDF) was used as the starting air electrode material, and 1-M lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) in carbonate-based solvents was used as the electrolyte. We found that Li 2O 2 was actively reactive to 1-methyl-2-pyrrolidinone and PVDF that were used to prepare the electrode. During the first charging (up to 4.6 V), O 2 was the main component in the gases released. The amount of O 2 measured by GC/MS was consistent with the amount of Li 2O 2 that decomposed during the electrochemical process as measured by the charge capacity, which is indicative of the good chargeability of Li 2O 2. However, after the cell was discharged to 2.0 V in an O 2 atmosphere and then recharged to ∼4.6 V, CO 2 was dominant in the released gases. Further analysis of the discharged air electrodes by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy indicated that lithium-containing carbonate species (lithium alkyl carbonates and/or Li 2CO 3) were the main discharge products. Therefore, compatible electrolytes and electrodes, as well as the electrode-preparation procedures, need to be developed for rechargeable Li-air batteries for long term operation.