- Changes of nitrides characteristics in Li-N system synthesized at different pressures
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For the Li-N system samples were obtained at pressures of nitrogen from 1 to 10 atm. Energy-dispersive X-ray (EDX) spectrum of a sample of Li-N subjected to degradation shows that lithium nitride turned into carbonate as evidenced by the predominant content of carbon and oxygen. Upon synthesis of lithium nitride at a positive pressure of nitrogen, the b-modification is formed, which can be achieved at a pressure 500 times lower than that described in literature, required to create a high-pressure phase. The increase in carbon content with increasing of synthesis pressure of lithium nitride confirms the change in stoichiometry of its structure formed with high nitrogen content.
- Ignatenko, Oleg V.,Komar, Valery A.,Leonchik, Sergey V.,Shempel, Natalia A.,Ene, Antoaneta,Cantaragiu, Alina,Frontasyeva, Marina V.,Shvetsov, Valery N.
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- On the incompatibility of lithium-O2 battery technology with CO2
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When solubilized in a hexacarboxamide cryptand anion receptor, the peroxide dianion reacts rapidly with CO2 in polar aprotic organic media to produce hydroperoxycarbonate (HOOCO2-) and peroxydicarbonate (-O2COOCO2-). Peroxydicarbonate is subject to thermal fragmentation into two equivalents of the highly reactive carbonate radical anion, which promotes hydrogen atom abstraction reactions responsible for the oxidative degradation of organic solvents. The activation and conversion of the peroxide dianion by CO2 is general. Exposure of solid lithium peroxide (Li2O2) to CO2 in polar aprotic organic media results in aggressive oxidation. These findings indicate that CO2 must not be introduced in conditions relevant to typical lithium-O2 cell configurations, as production of HOOCO2- and -O2COOCO2- during lithium-O2 cell cycling will lead to cell degradation via oxidation of organic electrolytes and other vulnerable cell components.
- Zhang, Shiyu,Nava, Matthew J.,Chow, Gary K.,Lopez, Nazario,Wu, Gang,Britt, David R.,Nocera, Daniel G.,Cummins, Christopher C.
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- A study of binary iron/lithium organometallic complexes as single source precursors to solid state cathode materials for potential Li ion battery application
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Solid state and solution phase decomposition of organometallic half sandwich and sandwich complexes of type [CpFeCODLi × DME] 1, [CpFeCODLi × TMEDA] 2 and [(Cp)2FeLi2 × 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, Fe3C and Li2O/Li 2CO3 at temperatures above 200 °C. Amorphous α-LiFeO2 is formed in the temperature range of 200-400 °C in the presence of oxygen. Crystalline α-LiFeO2 is formed only above 400 °C using 1. Elemental analysis of the LiFeO2 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 2CO3 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 2Fe3O5, Li5FeO4 and Fe3C depending on the solvent to precursor ratio in contrast to the α-LiFeO2 phase formed under pure solid state decomposition conditions. However, all lithium ferrites (Li2Fe3O 5, Li5FeO4) are converted to α-LiFeO 2 when oxidized above 500 °C. The α-LiFeO2 products were further characterized by IR, XPS, and TEM. Electrochemical analysis of the α-LiFeO2 was performed, showing a moderate initial capacity of 13 mAh/g.
- Khanderi, Jayaprakash,Schneider, J?rg J.
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- Synthesis of Li4SiO4 by a modified combustion method
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We report for the first time the synthesis of Li4SiO4 by the modified combustion method, a rapid chemical process that takes 5 min for completion. This method uses nonoxidizer compounds instead of nitrate mixtures, which are not always commercially available. The effects of the following parameters on the production of Li4SiO4 were studied: (1) different lithium hydroxide:silicic acid:urea (LiOH:H 2SiO3:CH4N2O) molar ratios; (2) the presence of air flow in the furnace chamber; and (3) the furnace heating temperature. It was found that LiOH:H2SiO3:CH 4N2O molar ratios 6:1:3 heated at 1100°C in the presence of additional air in the muffle chamber formed the best precursors to produce Li4SiO4.
- Cruz, Daniel,Bulbulian, Silvia
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- Characterization of Li1-xNi1+xO2 prepared using succinic acid as a complexing agent
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Li1-xNi1+xO2 was prepared by a polymerized complex method using succinic acid as a complexing agent. Ethanolic solutions of lithium acetate dihydrate, nickel acetate tetrahydrate, and succinic acid were mixed to form carboxylate precursors, which were subsequently calcined at 650-800°C for 14-48 h. TGA curves of metal acetates, succinic acid, and the precursors were characterized to determine weight loss and formation temperature of the oxide. By using XRD, SEM, and EDX, pure crystals of Li 1-xNi1+xO2 were detected at 750 and 800°C. The maximum and minimum intensity ratios of XRD spectra show that the optimum calcination condition is 750°C for 40 h. At 650-800°C, the particle size distribution is in the range of 0.35-39 μm. Pleiades Publishing, Inc., 2006.
- Thongtem, Titipun,Thongtem, Somchai
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- Lithium silicate nanosheets with excellent capture capacity and kinetics with unprecedented stability for high-temperature CO2capture
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An excessive amount of CO2is the leading cause of climate change, and hence, its reduction in the Earth's atmosphere is critical to stop further degradation of the environment. Although a large body of work has been carried out for post-combustion low-temperature CO2capture, there are very few high temperature pre-combustion CO2capture processes. Lithium silicate (Li4SiO4), one of the best known high-temperature CO2capture sorbents, has two main challenges, moderate capture kinetics and poor sorbent stability. In this work, we have designed and synthesized lithium silicate nanosheets (LSNs), which showed high CO2capture capacity (35.3 wt% CO2capture using 60% CO2feed gas, close to the theoretical value) with ultra-fast kinetics and enhanced stability at 650 °C. Due to the nanosheet morphology of the LSNs, they provided a good external surface for CO2adsorption at every Li-site, yielding excellent CO2capture capacity. The nanosheet morphology of the LSNs allowed efficient CO2diffusion to ensure reaction with the entire sheet as well as providing extremely fast CO2capture kinetics (0.22 g g?1min?1). Conventional lithium silicates are known to rapidly lose their capture capacity and kinetics within the first few cycles due to thick carbonate shell formation and also due to the sintering of sorbent particles; however, the LSNs were stable for at least 200 cycles without any loss in their capture capacity or kinetics. The LSNs neither formed a carbonate shell nor underwent sintering, allowing efficient adsorption-desorption cycling. We also proposed a new mechanism, a mixed-phase model, to explain the unique CO2capture behavior of the LSNs, using detailed (i) kinetics experiments for both adsorption and desorption steps, (ii)in situdiffuse reflectance infrared Fourier transform (DRIFT) spectroscopy measurements, (iii) depth-profiling X-ray photoelectron spectroscopy (XPS) of the sorbent after CO2capture and (iv) theoretical investigation through systematic electronic structure calculations within the framework of density functional theory (DFT) formalism.
- Belgamwar, Rajesh,Maity, Ayan,Das, Tisita,Chakraborty, Sudip,Vinod, Chathakudath P.,Polshettiwar, Vivek
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- Synthesis and CO2 adsorption characteristics of lithium zirconates with high lithia content
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Pure monoclinic phase Li6Zr2O7 and rhombohedral phase Li8ZrO6 that coexisted with a fraction of Li6Zr2O7, are synthesized by a liquid phase coprecipitation method and characterized by X-ray diffraction, scanning electron microscopy, and thermo-gravimetric analysis. The high-temperature CO 2 uptake properties of both samples are systematically investigated. The temperature effect tests indicate that, in the case of low temperature (2 uptake rates because of the inhibited diffusion of CO2 in the solid carbonate shell; while at the temperature above the melting point of Li2CO 3 (about 983 K), the CO2 uptake rates are enhanced dramatically for both Li6Zr2O7 and Li 8ZrO6, and achieved about 12.3% weight gain and 35.0% weight gain within 15 min at 1073 K, respectively. The thermal stability tests indicate that both samples exhibit gradually reduced capacities during the multicycle processes. The analysis of the crystalline structure reveals that the reduced capacities are resulted from the loss of lithia under high temperatures. Finally, the possible adsorption pathways for both monoclinic phase Li6Zr2O7 and rhombohedral phase Li 8ZrO6 are suggested as well.
- Yin, Xian-Sheng,Li, Shao-Peng,Zhang, Qin-Hui,Yu, Jian-Guo
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- Electrochemical Decomposition of Li4SiO4 and Li2TiO3 in Solid-state Thermal Cells
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Cells of the type Au/Li4SiO4/Au and Au/Li2TiO3/Au behave as secondary cells at high temperatures, >/=400 deg C.The cell reactants are created in situ by charging the cells in air at e.g. 1.5 V.Electrochemical decomposition of the solid electrolytes occurs giving, as solid products, Li2CO3 at the negative electrode and Li2SiO3 and TiO2, respectively, at the positive electrode.Under different charging conditions other products may be obtained with the Li2TiO3-containing cell.The products of charging form as a layer on the surfaces of the pellet and the gold electrodes appear to take no part in the reactions.The charged cells have open-circuit voltages in the range 0.4 - 0.5 V at ca. 500 deg C and give discharge currents of e.g. 10 - 100 μA through a 10E4 Ω load resistance for several days.
- Aceves, Juan M.,West, Anthony R.
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- Evidence of CO2 chemisorption at high temperature in lithium Gallate (Li5GaO4)
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Li5GaO4 was tested as a possibleCO2 captor. Li5GaO4 was synthesized by solid-state reaction, structurally characterized, and then thermally treated under a CO2 flow, from 30 to 900 °C, having the highest CO2 chemisorption at around 709 °C. The results clearly showed that Li5GaO4 isable to trap CO2 chemically in two different steps. The CO2 quantity trapped was equal to 8.9 mmol g-1, which is considerablyhigh in comparison to other ceramics.
- Avalos-Rendon, Tatiana,Pfeiffer, Heriberto
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- Thermally driven interfacial degradation between Li7La3Zr2O12 electrolyte and LiNi0.6Mn0.2Co0.2O2 cathode
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Solid-state batteries offer higher energy density and enhanced safety compared to the present lithium-ion batteries using liquid electrolytes. A challenge to implement them is the high resistances, especially at the solid electrolyte interface with the cathode. Sintering at elevated temperature is needed in order to get good contact between the ceramic solid electrolyte and oxide cathodes and thus to reduce contact resistances. Many solid electrolyte and cathode materials react to form secondary phases. It is necessary to find out which phases arise as a result of interface sintering and evaluate their effect on electrochemical properties. In this work, we assessed the interfacial reactions between LiNi0.6Mn0.2Co0.2O2 (NMC622) and Li7La3Zr2O12 (LLZO) as a function of temperature in air. We prepared model systems by depositing thin-film NMC622 cathode layers on LLZO pellets. The thin-film cathode approach enabled us to use interface-sensitive techniques such as X-ray absorption spectroscopy in the near-edge as well as the extended regimes and identify the onset of detrimental reactions. We found that the Ni and Co chemical environments change already at moderate temperatures, on-setting from 500 °C and becoming especially prominent at 700 °C. By analyzing spectroscopy results along with X-ray diffraction, we identified Li2CO3, La2Zr2O7, and La(Ni,Co)O3 as the secondary phases that formed at 700 °C. The interfacial resistance for Li transfer, measured by electrochemical impedance spectroscopy, increases significantly upon the onset and evolution of the detected interface chemistry. Our findings suggest that limiting the bonding temperature and avoiding CO2 in the sintering environment can help to remedy the interfacial degradation.
- Kim, Younggyu,Kim, Dongha,Bliem, Roland,Vardar, Gülin,Waluyo, Iradwikanari,Hunt, Adrian,Wright, Joshua T.,Katsoudas, John P.,Yildiz, Bilge
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- Adsorption and electrodeposition on SnO2 and WO3 electrodes in 1 M LiClO4/PC. In situ light scattering and in situ atomic force microscopy studies
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A novel spectroscopic in situ light scattering technique was used with in situ atomic force microscopy (AFM) to study electrode surfaces subjected to adsorption and electrodeposition. Tin dioxide and tungsten trioxide were used as electrodes in a 1 M LiClO4/propylene carbonate electrolyte. Both in situ methods showed the same increase in surface roughness immediately after the electrode was immersed in the electrolyte. The onset potential for electrodeposition could be determined; its specific value depended on the film composition as well as on the composition and purity of the electrolyte. A potential step technique revealed a progressive growth of the first electrodeposited layer. The growth mode after fully developed electrodeposition was characterized by a preferential growth of large crystals, evident from light scattering as well as AFM. Our experimental techniques make it possible to determine whether electrodeposition or electrochromism, due to electrochemical insertion of ionic species, dominates the observed modulation of the optical properties. The deposited layer was investigated using infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Although the composition of this layer cannot be stated conclusively, it most likely contains lithium alkyl carbonate species.
- Isidorsson,Lindstroem,Granqvist,Herranen
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- Time-Resolved Synchrotron Powder X-ray Diffraction Studies on the Synthesis of Li8SiO6 and Its Reaction with CO2
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Lithium oxosilicate was synthesized via the solid-state method using Li2O and SiO2 as starting reactants. In situ synchrotron powder X-ray diffraction (SPRXD) coupled with Rietveld refinement allowed describing the synthesis as a two-step process where Li2O and SiO2 react to form Li4SiO4 and, at higher temperatures, lithium orthosilicate reacts with the remaining Li2O to form Li8SiO6. Time-resolved measurements allowed determining the temperatures at which each phase transformation occurs as well as the time required to complete the synthesis. The CO2 capture properties of Li8SiO6 in the temperature range from room temperature to 770 °C were studied in detail by time-resolved in situ SPXRD. The crystallographic phases present during Li8SiO6 carbonation were identified and quantified via Rietveld analysis. Results showed that, within the temperature range from 200 to 690 °C, Li8SiO6 carbonation produces Li4SiO4 and Li2CO3, while, at temperatures from 690 to 750 °C, a secondary reaction occurs, where previously formed Li4SiO4 reacts with CO2, producing Li2SiO3 and Li2CO3. These findings allowed proposing a mechanism of reaction for Li8SiO6 carbonation in the temperature range that is of interest for high temperature solid-state sorbents.
- Cova, Federico,Amica, Guillermina,Kohop??, Katja,Blanco, Maria Valeria
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- Three-step calcination synthesis of high-purity Li8ZrO 6 with CO2 absorption properties
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Li8ZrO6 contains a high lithium content and may bear a great ability of CO2 absorption, yet the reports about the properties of CO2 absorption on Li8ZrO6 are few to date for its difficulty in production. In this paper, high-purity Li 8ZrO6 is synthesized via a three-step calcination method combined with an effective lithium source and a suitable initial Li/Zr molar ratio. The produced Li8ZrO6 possesses a great CO 2 absorption capacity of about 53.98 wt % at 998 K, which could be well-maintained in a wide range of CO2 partial pressures of 0.1-1.0 bar although it decreased gradually during the multicycle process of CO 2 absorption-desorption in a 10% CO2 feed stream because of the high working temperature. These properties imply that Li 8ZrO6 may be a new option for high-temperature CO 2 capture applied in industrial processes such as a steam methane reformer.
- Yin, Xian-Sheng,Zhang, Qin-Hui,Yu, Jian-Guo
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- Dependence of electrochemical properties of spinel LiMn2O4 on Li2CO3 with micro-flaky, micro-flower and nanorod morphologies
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Herein, the dependence of spinel LiMn2O4 on Li2CO3 with micro-flaky, micro-flower and nanorod morphologies is investigated. The results show that the as-synthesized LiMn2O4 with micron sized Li2CO3 as raw materials have a much higher discharge capacity than that of the one prepared with nano sized Li2CO3. It delivers an initial charge capacity of 110.1, 105.2 and 104.9 mA h g-1 followed by a discharge capacity of 109.1, 103.9 and 104.2 mA h g-1 with the micro-flower, nanorod and micro-flaky Li2CO3 morphologies, respectively, at room temperature (about 99% of the charge capacity is discharged). The smaller specific surface area is found in the spinel LiMn2O4 with micron sized Li2CO3, resulting in a better stable electrochemical performance in LiMn2O4 with micro-flower and micro-flaky Li2CO3. Their capacities are maintained at 99.2 mA h g-1 and 94.2 mA h g-1 after 100 cycles at 1C rate. The capacity retention was more than 90% at the 100th cycle with the micron-sized Li2CO3. Moreover, the as-synthesized spinel LiMn2O4 with micro-flower Li2CO3 retained more than 95% of its initial discharge capacity (92 mA h g-1) after 200 cycles at 2C rate. The cubic spinel structure was detected after 200 cycles of LiMn2O4 at 2C rate.
- Li, Lang,Sui, Jinsong,Huang, Rui,Xiang, Wei,Qin, Wei
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- REMARKS ON THE BINARY SYSTEMS Li//2O-Me//2O//5 (Me equals Nb,Ta).
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In the Li//2O-Ta//2O//5 system there are two new defective phases: Li//3//. //5TaO//4//. //2//5 and Li//1//6Ta//4O//1//8, with anionic vacancies. At 700 degree C these phases are characterized by disordered distribution of Li** plus and Ta**5** plus ions, like Li//3TaO//4 itself. At temperatures higher than 700 degree C a gradual cation ordering occurs, and the x-ray powder diffraction patterns show progressively increasing superstructure reflections similar to the ordering process of cations in Li//3TaO//4. In the examined temperature range (700-1000 degree C) the equilibrium series Li//3TaO//4-Li//3//. //5TaO//4//. //2//5-Li//1//6Ta//4O//1//8-Li//7TaO//6-Li//2O was assessed. In the system Li//2O-Nb//2O//5, an analogous series only for T greater than equivalent to 900 degree C was verified.
- Abbattista, F.,Vallino, M.,Mazza, D.
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- Selective production of acetone in the electrochemical reduction of CO2 catalyzed by a Ru-naphthyridine complex
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The controlled potential electrolysis of [Ru(bpy)(napy)2(CO)2](BF4)2 (1; bpy = 2,2'-bipyridine, napy = 1,8-naphthyridine) in the presence of LiBF4 in CO2-saturated DMSO at -1.65 V (vs. Ag/Ag+) produced CO and Li2CO3 [Eq. (a)], while similar electrolysis in the presence of (CH3)4NBF4 resulted in formation of acetone together with (CH3)3N and {(CH3)4N}2CO3 [Eq. (b)]. This represents the first almost selective generation of acetone upon electrochemical reduction of CO2. The selectivity is ascribed to depression of reductive cleavage of the Ru-CO bond of 1 due to an attack of the nonbonded nitrogen atom of napy at the carbonyl carbon atom.
- Mizukawa, Tetsunori,Tsuge, Kiyoshi,Nakajima, Hiroshi,Tanaka, Koji
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- Study of the phases in a copper cathode during an electrodeposition process for obtaining Cu-Li alloys
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The evolution of Cu-18at%Li crystals, Cu2O, Li2CO3, and CuO phases, which nucleate and grow during the electrodeposition process in a copper cathode, was examined. The electrodeposition process was mainly responsible for promoting the formation of copper oxides and lithium-carbonates in the cathode. The evolution of both the quantity of Cu-Li crystals formed at the surface of the cathode and the total lithium concentration of the sample as a function of the electrodeposition time was studied.
- Lambri,Perez-Landazabal,Penaloza,Herrero,Recarte,Ortiz,Woerner
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- Reaction mechanisms of Li0.30La0.57TiO3 powder with ambient air: H+/Li+ exchange with water and Li2CO3 formation
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The proton/lithium exchange property of the lithium lanthanum titanate Li0.30La0.57TiO3 (named LLTO) is shown to occur at room temperature under ambient air. The 1H and 7Li MAS NMR, TGA analysis and IR spectroscopy techniques are used to probe reaction mechanisms. XRPD analysis gives evidence of the topotactic character of this exchange reaction. As for exchange in aqueous solution, it is shown that Li 0.30La0.57TiO3 is able to dissociate water on the grain surface and then to exchange H+ for Li+ into the perovskite structure. Lithium hydroxide is then formed on the grain surface and afterwards reacts with CO2 contained in air to form Li 2CO3. It is shown that this mechanism is reversible. When the aged sample (aging in air for 5 months at room temperature) is annealed at 400°C for two hours, the initial LLTO sample is totally recovered, a mass loss is observed and the carbonate signal in IR spectra disappears, demonstrating the reversibility of the carbonation reaction process.
- Boulant, Anthony,Bardeau, Jean Francois,Jouanneaux, Alain,Emery, Joel,Buzare, Jean-Yves,Bohnke, Odile
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- Mechanism of a reversible CO2 capture monitored by the layered perovskite Li2SrTa2O7
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We demonstrate for the first time, a new CO2 capture ability monitored by a Ruddelsden-Popper compound. Under a humid CO2 atmosphere, Li2SrTa2O7 is transformed into LiHSrTa2O7 re
- Galven, Cyrille,Fourquet, Jean-Louis,Suard, Emmanuelle,Crosnier-Lopez, Marie-Pierre,Le Berre, Franoise
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- Colloidal-crystal-templated synthesis of ordered macroporous electrode materials for lithium secondary batteries
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This paper presents a general method of preparing three-dimensionally ordered macroporous (3DOM) electrode materials, including both cathode materials (V2O5 and LiNiO2) and an anode material (SnO2). The method is based on templated precipitation of inorganic precursors within a colloidal crystal of poly(methyl methacrylate) spheres and subsequent chemical conversion. 3DOM electrodes possess several features of interest in the design of novel battery materials, such as high accessible surface areas, continuous networks, and structural features on the nanometer scale. Optimal synthesis conditions and structural features of 3DOM electrode materials are described on the basis of X-ray diffraction, scanning electron microscopy, nitrogen adsorption, and chemical analysis.
- Yan, Hongwei,Sokolov, Sergey,Lytle, Justin C.,Stein, Andreas,Zhang, Fan,Smyrl, William H.
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- A Biomimetic Nickel Complex with a Reduced CO2 Ligand Generated by Formate Deprotonation and Its Behaviour towards CO2
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Reduced CO2 species are key intermediates in a variety of natural and synthetic processes. In the majority of systems, however, they elude isolation or characterisation owing to high reactivity or limited accessibility (heterogeneous systems),
- Zimmermann, Philipp,Hoof, Santina,Braun-Cula, Beatrice,Herwig, Christian,Limberg, Christian
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- Selective CO2 Splitting by Doubly Reduced Aryl Boranes to Give CO and [CO3]2?
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Alkali metal salts M2[1] (M=Li, Na) of doubly reduced 9,10-dimethyl-9,10-dihydro-9,10-diboraanthracene (1) instantaneously add the C=O bond of CO2 across their boron centers to furnish formal [4+2]-cycloadducts M2[2]. If only 1 equiv of CO2 is supplied, these products are stable. In the presence of excess CO2, however, C?O bond cleavage occurs and an O2? equivalent is transferred to CO2 to furnish CO and [CO3]2?. With M=Li, Li2CO3 precipitates and the neutral 1 is liberated such that it can be reduced again to establish a catalytic cycle. With M=Na, [CO3]2? remains coordinated to both boron atoms in a bridging mode (Na2[4]). A mechanistic scenario is proposed, based on isolated intermediates and model reactions.
- von Grotthuss, Esther,Prey, Sven E.,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias
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- Effect of excess Li+in solution on LiFePO4preparation via wet chemical method
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Olivine structure LiFePO4has attracted much attention as a promising cathode material for lithium ion batteries, and many approaches have been developed to produce electrochemically active LiFePO4at low cost. Here lithium iron phosphate (LiFePO4) was prepared via co-precipitation method by using FeSO4·7H2O, LiOH·H2O, and o-H3PO4as the raw materials. The effects of Li:Fe:P molar ratios and solution pH value on the synthesis of LiFePO4were studied. The results illustrated that besides of the pH value parameter which was reported in many other previous researches, excess Li+in the solution was another essential condition for pure LiFePO4preparation. It suggested that excessive LiOH was not only a pH regulator, but also a precipitation promoter. Maintaining a certain excess Li+ion in solution was an efficient measure to avoid the formation of impurities.
- He, Lihua,Zhao, Zhongwei
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- MOSSBAUER STUDY OF THE THERMAL DECOMPOSITION OF ALKALI TRIS(OXALATO)FERRATES(III).
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The thermal decomposition of alkali (Li,Na,K,Cs,NH//4) tris(oxalato)ferrates(III) has been studied at different temperatures up to 700 degree C using Mossbauer, infrared spectroscopy, and thermogravimetric techniques. The formation of different intermedia
- Brar,Randhawa
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- Gel-combustion synthesis of Li1.2Mn0.4Co 0.4O2 composites with a high capacity and superior rate capability for lithium-ion batteries
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Owing to the merits of high capacity and low cost, Li-rich layered composite cathode materials have received extensive attention. Nevertheless, such materials always suffer from a poor rate capability, which seriously hinders their widespread practical applications. In this work, Li 1.2Mn0.4Co0.4O2 composites were fabricated by a gel-combustion method, in which lithium carbonates formed by an in situ burning reaction were homogeneously mixed with metal oxides, leading to excellent electrochemical properties. The sintering temperature and time were optimized to 900 °C and 15 h. The samples prepared at optimum conditions exhibited a high discharge capacity and excellent rate capability. At a current density of 20 mA g-1, the specific discharge capacity was 310.5 mA h g-1 for the first cycle and the capacity retention was 75.8% after 30 cycles. When the current densities increase by 10 times to reach 200 mA g -1, the initial discharge capacity is still as high as 241.4 mA h g-1, superior to that of 203 mA h g-1 at the same current density reported previously by the oxalate-precursor method. Even when the current densities increase by 20 times, the capacity remained as high as 203.7 mA h g-1, and the capacity retention was 79.4% over 30 cycles. The high discharge capacity and improved rate capability of the optimized sample were beneficial with a perfect layered structure with c/a >5.0, appropriate particle size of about 450 nm, high lithium ion diffusion coefficient around 1.42 × 10-13 cm2 s-1, and the presence of a maximum content of Mn3+ (11.6%), as determined by XPS. The preparation method reported herein may provide hints for obtaining various advanced Li-rich layered composite materials for use in high-performance energy storage and conversion devices.
- Fu, Chaochao,Li, Guangshe,Luo, Dong,Zheng, Jing,Li, Liping
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- H2O-induced self-propagating synthesis of hierarchical porous carbon: A promising lithium storage material with superior rate capability and ultra-long cycling life
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Hierarchical porous carbon (HPC) has attracted much attention in tackling global environmental and energy problems. For the state-of-the-art routes to synthesize HPC from organic compounds, the emission of carbon dioxide (CO2) and gaseous pollutants is inevitable during thermal carbonization. Herein, we report an environmentally benign and high-yield route to synthesize HPC from CO2via H2O-induced self-propagating reactions. By introducing an initiator of H2O, CO2 can react with lithium hydride (LiH) to produce HPC in 13 seconds at low temperatures. The as-synthesized HPC exhibits an interconnected micro-meso-macropore network structure with a high porosity of 83%. The formation mechanism of HPC is discussed on the basis of the conversion reactions from CO2 to C and the gas blowing effect in producing hierarchical porosity. The HPC evaluated as an anode material for lithium-ion batteries not only delivers a high reversible capacity of ～1150 mA h g-1 at a current density of 0.2 A g-1, but also exhibits superior rate capability (～825 mA h g-1 at 1.0 A g-1) and excellent cycling properties (up to 2000 cycles). This research opens a new avenue both to synthesize HPC from CO2 on a large scale and to mitigate greenhouse gas from the atmosphere.
- Liang, Chu,Liang, Sheng,Xia, Yang,Chen, Yun,Huang, Hui,Gan, Yongping,Tao, Xinyong,Zhang, Jun,Zhang, Wenkui
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- Features of the Thermolysis of Li, Na, and Cd Maleates
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Abstract: Processes of the multi-stage decomposition of maleic acid and Li, Na, and Cd maleates in an inert atmosphere are studied via thermal analysis with synchronous analysis of the composition of the released gases. Reaction mechanisms are proposed according to the data on the mass loss stages determined via thermal analysis, gaseous products, and the final solid decomposition products. It is shown that when heated to 700°C, Li and Na carbonates incorporated into the porous carbon matrix are the final products. Above 350°C, cadmium is reduced from oxide to metal and evaporates to form a porous carbon residue as the only product of thermolysis. All carbon products are X-ray amorphous. Maleic acid decomposes completely into gaseous products in the range of 133–239°C. The maleate ion is more stable in the structure of lithium maleate than in free maleic acid, and Na and Cd cations reduce its stability.
- Avdin, V. V.,Merzlov, S. V.,Nayfert, S. A.,Polozov, M. A.,Polozova, V. V.,Sakthi Dharan, C. P.,Taskaev, S. V.,Zherebtsov, D. A.
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p. 1311 - 1318
(2020/07/21)
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- The Alkali Metal Salts of Methyl Xanthic Acid
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Methyl xanthates of the type M(SSC-OMe) (M = Li–Cs) are readily formed when carbon disulfide is reacted with the corresponding alkali metal hydroxides in methanol exposed to air, or with the alkali metal methoxides in dry methanol or THF under exclusion of air. The reactions are easily monitored by 13C NMR spectroscopy. The Na, K, Rb, and Cs salt could be isolated in high yields, while the Li salt decomposed upon attempted isolation. All compounds are readily complexed by crown ethers and form isolable 1:1 adducts, including the elusive Li salt. All products were studied by NMR (1H, 13C, and alkali metal nuclei) and IR spectroscopy, and most of them where structurally characterized by single-crystal X-ray diffraction. Li(SSC-OMe)(12c4) (12c4 = [12]crown-4) and Cs(SSC-OMe)(18c6) (18c6 = [18]crown-6) represent the first structurally characterized lithium and caesium xanthate complexes, respectively.
- Liebing, Phil,Schmeide, Marten,Kühling, Marcel,Witzorke, Juliane
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p. 2428 - 2434
(2020/06/17)
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- A Carbon-Neutral CO2 Capture, Conversion, and Utilization Cycle with Low-Temperature Regeneration of Sodium Hydroxide
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A highly efficient recyclable system for capture and subsequent conversion of CO2 to formate salts is reported that utilizes aqueous inorganic hydroxide solutions for CO2 capture along with homogeneous pincer catalysts for hydrogenation. The produced aqueous solutions of formate salts are directly utilized, without any purification, in a direct formate fuel cell to produce electricity and regenerate the hydroxide base, achieving an overall carbon-neutral cycle. The catalysts and organic solvent are recycled by employing a biphasic solvent system (2-MTHF/H2O) with no significant decrease in turnover frequency (TOF) over five cycles. Among different hydroxides, NaOH and KOH performed best in tandem CO2 capture and conversion due to their rapid rate of capture, high formate conversion yield, and high catalytic TOF to their corresponding formate salts. Among various catalysts, Ru- and Fe-based PNP complexes were the most active for hydrogenation. The extremely low vapor pressure, nontoxic nature, easy regenerability, and high reactivity of NaOH/KOH toward CO2 make them ideal for scrubbing CO2 even from low-concentration sources - such as ambient air - and converting it to value-added products.
- Kar, Sayan,Goeppert, Alain,Galvan, Vicente,Chowdhury, Ryan,Olah, Justin,Prakash, G. K. Surya
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supporting information
p. 16873 - 16876
(2018/11/06)
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- PROCESS FOR PRODUCING LACTATE
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A process for producing an alkali metal lactate comprising: a) reacting a stream rich in saccharide with barium hydroxide to produce a first reaction mixture comprising barium lactate; and b) contacting at least a portion of said first reaction mixture with an alkali metal hydroxide to produce a second reaction mixture comprising alkali metal lactate and solid barium hydroxide, wherein the alkali metal is selected from the group consisting of sodium, lithium and potassium.
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Page/Page column 18
(2015/11/17)
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- Layered inorganic-organic frameworks based on the 2,2-dimethylsuccinate ligand: Structural diversity and its effect on nanosheet exfoliation and magnetic properties
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The structures of four new 2,2-dimethylsuccinate frameworks suitable for exfoliation into nanosheets using ultrasonication are reported. These hybrid compounds contain either monovalent (Li+) or divalent (Co 2+ and Zn2+) cations, and they all feature hydrophobically capped covalently bonded layers that only interact with each other via weak van der Waals forces. Critically this shows that the use of this dicarboxylate ligand generally yields two dimensional compounds suitable for simple and affordable nanosheet exfoliation. This extends the range of frameworks that can be exfoliated and highlights the 2,2-dimethylsuccinate ligand as an excellent versatile platform for the production of nanosheets. The topologies of the layers in each framework were found to vary significantly and this appears to have a significant effect on the relative size of the nanosheets produced; increased space between methyl groups and more extensive inorganic connectivity appears to favour the formation of thin nanosheets with larger lateral dimensions. Additionally the magnetic properties of two of these frameworks were examined, and it was found that both exhibit strong low dimensional antiferromagnetic coupling despite their well-separated layers preventing three dimensional magnetic order.
- Saines, Paul J.,Tan, Jin-Chong,Yeung, Hamish H.-M.,Barton, Phillip T.,Cheetham, Anthony K.
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p. 8585 - 8593
(2012/10/08)
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- PROCESSES FOR PREPARING HIGHLY PURE LITHIUM CARBONATE AND OTHER HIGHLY PURE LITHIUM CONTAINING COMPOUNDS
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The invention generally relates to methods of selectively removing lithium from various liquids, methods of producing high purity lithium carbonate, methods of producing high purity lithium hydroxide, and methods of regenerating resin.
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- The influence of temperature (20-1000 °C) on binary mixtures of solid solutions of CH3COOLi·2H2O-MgHPO4·3H2O
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Thermally induced phase transitions (20-1000 °C) in the substrates and binary mixtures of CH3COOLi·2H2O(1)-MgHPO4·3H2O(11) have been analysed. Changes taking place on dehydration and thermal dissociation of bina
- Umbreit, Micha? H.,Paukszta, Dominik
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p. 3620 - 3636
(2010/06/12)
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- Thermal analysis of lithium peroxide prepared by various methods
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Behavior of lithium peroxide samples at heating in air was studied by the methods of thermogravimetric analysis (TGA) and differential thermal analysis (DTA). In the temperature range from 32 to 82°C all the studied samples we found to react with water vapor forming lithium peroxide monohydrate as confirmed by the methods of chemical analysis and of qualitative X-ray phase analysis. It was found experimentally that in the temperature range from 340 to 348°C lithium peroxide began to decompose into lithium oxide and oxygen, the starting temperature depended on the method of preparation of lithium peroxide. For all the studied samples polymorphism in the temperature range from 25 to 340°C was not detected.
- Ferapontov,Kokoreva,Kozlova,Ul'Yanova
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p. 891 - 894
(2011/04/16)
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- Synthesis, short-range structure, and electrochemical properties of new phases in the Li-Mn-N-0 system
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A crystal-chemical exploration of part of the Li - Mn - N - O system was carried out. Several samples were synthesized using Li3N, Mn xN and Li2O and characterized with chemical analysis, XRD, XAS, and NMR. An increase in
- Cabana, Jordi,Dupre, Nicolas,Gillot, Frederic,Chadwick, Alan V.,Grey, Clare P.,Palacin, M. Rosa
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p. 5141 - 5153
(2009/10/23)
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- Characterization of Li1-x Ni1+x O2 prepared by the thermal-assisted precipitation process
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Li1-x Ni1+x O2 was prepared by the thermal-assisted precipitation process of LiOH ? H2O and Ni(CH3COO)2 ? 4H2O at a pH of 6-13 followed by the high temperature calcination for a variety of prolonged times. Phases, morphologies and constituents were characterized using an x-ray diffractometer (XRD), a scanning electron microscope (SEM), an energy dispersive x-ray (EDX) analyzer an atomic absorption spectrophotometer (AAS) and titration. Maximum [I(003)/I(104)] and minimum [I (006+102)/I(101)] intensity ratios were used to determine the preparation conditions. In addition, possible formation reactions of the precursors and calcined products were proposed.
- Thongtem, Titipun,Sitthikhankaew, Russamee,Thongtem, Somchai
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p. 515 - 519
(2008/10/09)
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- Characteristics of LiMO2 (M = Co, Ni, Ni0.2Co0.8, Ni0.8Co0.2) powders prepared from solution of their acetates
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Stoichiometric quantities of the acetates of lithium, cobalt and nickel were dissolved in distilled water and stirred with a magnetic stirrer. After complete dissolution was obtained, the solutions were heated at 120 °C under continuous stirring until some dark colored powder materials were formed. These precursor materials were divided into three batches and heated at 250 °C (for 24 h), 370 °C (for 24 h) and 800 °C for 10 h. The precursor and calcined samples were X-rayed. The X-ray diffractograms for the prepared samples were compared to that of commercialized samples and those published in the literature. The Bragg peak with Miller indices (0 0 3) in the diffractogram of the LiNi0.8Co0.2O2 prepared sample showed a lower intensity compared to the (1 0 4) peak. The ratio of the (0 0 3) to (1 0 4) peaks for the LiNi0.2Co0.8O2 sample is 1.56. Lattice parameters showed that the LiCoO2 and LiNi0.2Co0.8O2 samples produced by the method in the present investigation have potential to exhibit good electrochemical performance when used as electrodes in lithium ion batteries.
- Arof
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p. 288 - 291
(2008/10/09)
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- Thermal behaviour of pharmacologically active lithium compounds
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The thermal decompositions of a series of simple lithium compounds (carbonate, sulfate, acetate, citrates, aspartates and glutamates) currently used in the treatment of manic-depressive psychosis and related disorders were investigated by means of TG and DTA measurements in oxygen atmosphere. Pyrolysis residues were characterized by infrared spectroscopy. The stabilities of the hydrates and intermediate phases generated during the degradation processes are discussed.
- Tobon-Zapata,Ferret,Etcheverry,Baran
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- Reduction of CO2 Directed toward Carbon-Carbon Bond Formation
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This paper describes electrochemical reduction of CO2 directed toward carbon-carbon bond formation via metal-CO2 adducts. An electrophilic attack of CO2 to penta-coordinated low valent polypyridyl Ru complexes affords a Ru-η1-CO2 adduct, which is easily converted to Ru-CO species either by an acid-base equilibrium in protic media and oxide transfer to CO2 under aprotic conditions. Two-electron reduction of resultant Ru-CO in protic solutions competitively causes a cleavage of the Ru-CO bond (CO evolution) and formation of a thermally labile Ru-CHO bond. Besides further reduction of the latter to Ru-CH2OH as precursors to CH3OH and HOOCCH2OH, Ru-CHO reacts with CO2 to afford HCOOH with regenerating Ru-CO as the precursor to CO. Thus, the difficulty of multi-electron reduction of CO2 in protic solutions is ascribed to the thermal lability and strong hydride donor character of Ru-CHO. On the other hand, two-electron reduction of Ru-CO in the presence of (CH3)4N+ or CH3I under aprotic conditions produces thermally stable R-C(O)CH3, which works as a precursor to CH3C(O)CH3. Two-electron reduction of M3(μ3-S)2 clusters (M = Co, Rh, Ir) causes an M-M bond cleavage and the nucleophilicity of the μ3-S ligand is also enhanced. As a result, two CO2 molecules reductively activated probably on μ3-S and metal sites undergo the coupling reaction to give oxalate selectively.
- Tanaka, Koji
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- Composition-valence diagram and stoichiometry in the Li-Mn-O spinel system
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The synthesis of Li-Mn-O spinels with manganese valence > 3.5 has been investigated using thermogravimetry and X-ray analysis. The results are discussed as a function of starting reagents and processing temperature. Acetates and Y-MnO2 were found to react well at low temperature, especially for high Li/Mn ratios. -MnO2 could not be totally reacted, but yielded well-crystallized spinels. Shifts in composition due to the presence of secondary phases are discussed with the help of composition-valence diagrams. The variation of the spinel cell parameter along the LixMn3-xO4 (la = 8.4243 - 0.3753-(Li/Mn).Ve confirm that the composition of the end member Li4Mn5Oj2 cannot be reached in single phase form. & Gauthier-Villars.
- Cras,Strobel,Anne
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- Glycolic alcoholates formation in MmCuOn-ethylene glycol systems
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X-ray, microscopic, and thermogravimetric analyses were used to study the interaction of Bi2-xSr2Ca2Cu3O10+y, Ca2CuO3, Sr2CuO3, CaSrCuO3, SrCuO2, BaCuO2, and Li2CuO2 powders with ethylene glycol at room temperature. It was determined that glycolic alcoholates are obtained as a result of interaction of simple cuprates and ethylene glycol. The compounds M2[Cu(CH2OCH2OH)6] (M = Ca, Sr), M[Cu(CH2OCH2O)2] (M = Sr, Ba), Li2[Cu(CH2OCH2OH)4], and Li2[Cu(CH2OCH2O)2(H 2O)2] have been isolated and identified. Chemical transformation of Bi2-xSr2Ca2Cu3O10+y leads to the formation of glycolic alcoholates mixture with the compositions Sr[Cu(CH2OCH2O)2], Ca2[Cu(CH2OCH2OH)6], CaSr[Cu(CH2OCH2OH)6], and the unidentified amorphous phases containing bismuth and lead.
- Krasilnikov,Antsygina,Bazuev
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p. 565 - 572
(2008/10/08)
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- Tricyclic-pyridinylquinoline compounds, their preparation and use
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Fluorinated 10-(2,6-dimethyl-4-pyridinyl)-3-methyl-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acids and -benzothiazine-6-carboxylic acids of the formula STR1 wherein R is hydrogen, R' is hydrogen or fluoro, R" is alkyl of 1-3 carbon atoms and X is O or S are superior antibacterial agents.
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- Reductive Disproportionation of Carbon Dioxide by Dianionic Carbonylmetalates of the Transition Metals
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Carbon dioxide reacts readily with M2 (M=Li, Na, K, M'=W; M=K, M'=Cr, Mo, W) to give the corresponding group 6 hexacarbonyls and alkali metal carbonates.The reaction of Li2 with excess 13CO2 at -78 deg C gives , con
- Lee, Gary R.,Maher, John M.,Cooper, N. John
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p. 2956 - 2962
(2007/10/02)
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- CARBON DIOXIDE ACTIVATION BY LITHIUM METAL: PART 1. INFRARED SPECTRA OF Li + CO2 - , Li + C2O4 - AND Li22 + CO22 - IN INERT-GAS MATRICES.
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Lithium atoms react spontaneously with carbon dioxide to form Li** plus CO//2** minus and Li//2**2** plus CO//2**2** minus in inert gas matrices. Reaction of Li and CO//2 in an argon matrix leads also to the formation of Li** plus C//2O//4** minus . Two geometrical isomers of Li** plus CO//2** minus have been isolated in solid argon. One has a ring structure in which the metal interacts symmetrically with the two oxygen atoms, while in the second isomer the lithium atom is bonded to only one of the two oxygens.
- Kafafi,Hauge,Billups,Margrave
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p. 3886 - 3893
(2007/10/02)
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