LiOH Solution Research Articles

Stability of garnet-type solid electrolyte LixLa3A2 -yByO12 (A = Nb or Ta, B = Sc or Zr)

Garnet-type solid electrolytes LixLa3A2-yByO12 (A=Nb5+ or Ta5+, B=Sc3+ or Zr4+) were examined with respect to their stability in contact with lithium metal, water, and a liquid electrolyte for application in an aqueous lithium-air secondary battery. Electrolyte samples were synthesized by a solid state reaction method using a magnesia rather than alumina crucible to avoid aluminum contamination. The garnet-type electrolytes including Zr4+ ions exhibited higher ionic conductivity than those with Sc3+ ions. The electrolytes including Ta5+ were stable in contact with lithium metal, whereas those with Nb5+ were not. Lithium ions in all the samples were partly proton-exchanged in distilled water; however, the garnet-like structure remained unchanged as reported in many papers. In contrast, all the electrolyte samples were stable in the aqueous solution of 10M LiCl and 2M LiOH (suitable electrolyte for aqueous Li-air battery system). The garnet-type lithium ion conductors comprising Zr4+ and Ta5+ ions were revealed to be suitable for use as the protective membrane between the lithium metal electrode and aqueous electrolyte in rechargeable lithium-air batteries.

Surface Oxidation of Au(111) Electrode in Alkaline Media Studied by Using X-ray Diffraction and Infrared Spectroscopy: Effect of Alkali Metal Cation on the Alcohol Oxidation Reactions

The effects of alkali meal cation on the surface oxidation and alcohol oxidation reactions on Au(111) have been investigated using surface X-ray diffraction and infrared spectroscopy. It is known that alkali metal cations strongly affect the alcohol oxidation reactions on Pt(111); however, the oxidation reactions on Au(111) do not depend on alkali metal cations. Infrared spectroscopy reveals the formation of adsorbed OH in LiOH and CsOH solutions below the second anodic peak at 1.3 V. This result indicates that surface oxidation processes do not depend on alkali metal cations below 1.3 V. The interfacial structure, including the outer layer, of an Au(111) electrode has been determined using X-ray diffraction in LiOH and CsOH. During the surface oxidation, the Au(111) surface in CsOH gets roughened more remarkably than that in LiOH above 1.3 V. Li+ has a protective effect against surface roughening. Thus, the cationic effect is weaker in the potential region lower than the second anodic peak, which does no...

The effect of microarc oxidation and excimer laser processing on the microstructure and corrosion resistance of Zr–1Nb alloy

The main purpose of this research was to investigate the effect of microarc oxidation (MAO) and excimer laser processing on the corrosion resistance of Zr–1Nb alloy in service environment. The pre-oxide film was fabricated on the surface of Zr–1Nb cladding tubes by MAO processing, and then subjected to KrF excimer laser irradiation. The surface morphology of the pre-oxide film was observed using a scanning electron microscope; phase compositions and quantities were determined using an X-ray diffraction; surface roughness was determined using a profilometer; and thermal expansion coefficient was measured using a dilatometer. Autoclave experiments were conducted for 94 days in an aqueous condition of 360 °C under 18.6 MPa in 0.01 mol/L LiOH solutions. The results showed that MAO + laser treatment resulted in a significant increase in the corrosion resistance of Zr–1Nb cladding tubes at high temperatures, because laser melting and etching could lead to a reduction in surface roughness and an increase in compactness of the pre-oxide film, and laser processing could promote the transformation of m-ZrO2 phase to t-ZrO2 phase. The best corrosion resistance was obtained when the pulse energy was 500 mJ, scanning speed was 0.13 mm/s, and pulse number was 2400.

Preparation of H2TiO3–lithium adsorbent using low-grade titanium slag

H2TiO3–lithium adsorbent was obtained from the acid-modified precursor Li2TiO3, which was synthesized via the solid-phase reaction between LiOH·H2O and a Ti-rich material. The Ti-rich material containing 88.35% TiO2 was prepared from low-grade titanium slag via an upgrading process primarily involving alkaline roasting and acid leaching-hydrolysis. The parameters for the synthesis and acid treatment of the Li2TiO3 precursor were investigated. It was observed that monoclinic β-Li2TiO3 with good crystallization could be synthesized at 750°C with a Li/Ti molar ratio of 2.5. The adsorbent obtained under the optimized preparation conditions exhibited an excellent lithium adsorption capacity of up to 27.8mg/g in LiOH solution with a Li+ concentration of 2g/L, and the adsorption capacity stabilized at 23 to 24mg/g after several cycles. The adsorbent had better Li+ selectivity in the synthetic salt-lake brine solution. The separation coefficients of Li+ to Na+ and K+ reached 37.5 and 26.9, respectively.

Reliability tests of ionic polymer metallic composites in dry air for actuator applications

Electroactive polymers (EAPs) are capable of exhibiting large shape changes in response to electrical stimulation. EAPs can produce a large deformation with a low applied voltage for actuation applications. The IPMC (Ionic Polymer Metal Composite) is a well-known type of ionic EAP. It has numerous attractive advantages, such as low electrical energy consumption and being lightweight. The underlying mechanism of an IPMC actuator is the ionic diffusion when a voltage gradient is applied. As such, the characteristics of the ionic solution have a large impact on the physical properties of the IPMC. In this paper, reliability tests of IPMCs with a non-aqueous ionic solution are demonstrated. The Pt-IPMC with LiOH aqueous solution exhibits the best maximum displacement, but the water in the LiOH solution is electrolyzed easily because of the low electrolysis voltage (1.23V) of water. To ameliorate the electrolysis problems and improve the operation time, more appropriate solvents with a high electrolysis voltage and low vapor pressure should be chosen. Parylene-coating can also protect the IPMC from solvent loss. The reliability tests focus on the durability of IPMCs in dry air. Improvements in IPMC fabrication, such as Ag-IPMC, are discussed in this paper. Through the use of parylene protection and an ionic solution with a high electrolysis voltage, the lifetime of the Ag-IPMC in dry air is up to 15 times greater than that of the uncoated Ag-IPMC with aqueous solution. We have addressed potential issues regarding the dry air actuation of IPMCs, and found that the cracking of electrodes has a major impact on the reliability of the IPMCs in this study.

Electrolyte Effects on the Electrochemical Behavior of Electrolytic Manganese Dioxide in Alkaline Aqueous Media

Electrolytic manganese dioxide (EMD) is the cathode material typically used in primary alkaline cells, owing to its low cost and relatively high gravimetric capacity. These qualities also make it attractive as a cathode for secondary cells, though unfortunately its cycle-life is relatively short. The cycle-life can be improved under certain conditions, e.g. at limited depth of discharge [1]; there also reports of improved cycleability in LiOH solutions or against non-zinc electrodes [2]. We have investigated the effects of electrolyte composition on the electrochemical properties of EMD with cyclic voltammetry and galvanostatic cycling. More particularly, we focused on LiOH and KOH electrolytes, with ZnO present or absent. The structural evolution of the material during electrochemical cycling was studied using in situ synchrotron x-ray diffraction. While the structure of the EMD appears to remain largely intact after a single cycle in KOH solution, it undergoes an irreversible transformation at low depths of discharge when reduced in lithium hydroxide solutions. Both electrochemical and diffraction measurements indicate this transformation was complete within the first reduction, though the material undergoes further structural evolution with extended cycling. The electrochemical behavior of ramsdellite MnO2, the prototypical structure for EMD, was also examined in a LiOH electrolyte as a point of comparison. Ramsdellite underwent an irreversible transformation at low depths of discharge in a manner similar to that observed for EMD. The evolution of the diffraction pattern of the ramsdellite upon electrochemical reduction was very similar to that reported for chemically reduced ramsdellite in organic media [3]. In situ measurements with zincate-containing electrolyte showed ZnMn2O4 (hetaerolyte) to form sooner in LiOH solutions than KOH solutions. Curiously, hetaerolyte underwent some structural changes upon re-oxidation and we will provide some possible interpretations of this observation. Short-term (<30 cycles) capacity and cycleability trends observed as a function of the various electrolyte compositions and potential limits will also be presented. [1] K. Kordesch, J. Gsellmann, M. Peri, K. Tomantschger, R. Chemelli Electrochim. Acta 1981, 26, 1495-1504. [2] M. Minakshi Electrochem. Solid-State Lett. 2010, 13, A125-A127. [3] M.M. Thackeray, M.H. Rossouw, R.J. Gummow, D.C. Liles, K. Pearce, A. De Kock, W.I.F. David, S. Hull Electrochim. Acta 1993, 38, 1259-1267.

Excellent Stability of a Li-Ion-Conducting Solid Electrolyte upon Reversible Li+/H+ Exchange in Aqueous Solutions

Batteries with aqueous catholyte and Li metal anode have attracted intensive research interests due to their exceptional energy density and high charge/discharge rate. The long-term operation of such batteries requires particular conditions for the solid electrolyte separator between the anode and aqueous solutions. In addition to the compatibility with Li, the separator must be stable over a wide pH range. Unfortunately, no such compound has yet been reported. In this study, an excellent stability in neutral and strong basic solutions was observed in a Li-stable solid electrolyte, the cubic Li7La3Zr2O12 garnet. The material experienced a Li+/H+ exchange in aqueous solutions. Nevertheless, its structure remained unchanged even under a high exchange rate of 63.6%. When treated with a 2M LiOH solution, the Li+/H+ exchange was reversed without any structural change. These observations suggest that cubic Li7La3Zr2O12 is a promising candidate for the separator in aqueous lithium batteries.

Synthesis of highly crystalline LiMn2O4/multiwalled carbon nanotube composite material with high performance as lithium-ion battery cathode via an improved two-step approach

Facile synthesis of highly crystalline spinel-type LiMn2O4/multiwalled carbon nanotube (MWCNT) composite by a novel two-step approach is achieved. This approach involves an acetone-assisted hydrothermal reaction in LiOH solution using previously prepared birnessite MnO2/MWCNT composite as a manganese containing precursor. The lithium manganate spinel Li0.81Mn2O4/MWCNT composite delivers a high specific capacity of 145.4mAhg−1 at 0.1C-rate, which is close to the theoretic capacity of LiMn2O4 (148mAhg−1). Besides, it exhibits excellent high-rate capability and cyclability. For example, a discharge capacity of 114.8mAhg−1 is retained even at a high charge/discharge current rate of 20C. When it is repeatedly cycled at 1C rate for 1000 cycles, the specific capacity is decreased from the initial value of 140.4mAhg−1 to an end value of 98.7mAhg−1, giving 70.3% capacity retention.

Surface treatment of rare earth-magnesium–nickel based hydrogen storage alloy with lithium hydroxide aqueous solution

The alkaline treatments of rare earth-magnesium–nickel based hydrogen storage alloy with lithium hydroxide (LiOH) aqueous solutions of various concentrations (1 M, 2 M, 4 M, 5 M, and 6 M) were investigated. The morphology and composition of the alloy surface and the electrochemical characters of the electrode were tested. The discharge capacity and cycle life of the alloy electrode were effectively improved after the treatment with LiOH solution of 5 M or higher. The samples treated in 5 M LiOH for 1 h and 6 M LiOH for 10 min showed better electrochemical properties than the other samples. The passive oxide and hydroxide layer formed in LiOH solution increased the charge retention rate and decreased the high rate dischargeability of the alloy electrode. The high concentration LiOH solution diminished the formation of oxygen containing species on the alloy surface during the treatment. The LiOH solution can remove the Mg element on the alloy surface effectively.

ChemInform Abstract: Nano/Micro Structured Porous Li4Ti5O12 Synthesized by a Polyethylene Glycol Assisted Hydrothermal Method for High Rate Lithium‐Ion Batteries.

AbstractNano/micro structured porous Li4Ti5O12 for high rate Li‐ion batteries is prepared by mixing EtOH solutions of LiOH and PEG to which H2O and (Bu‐O)4Ti is given under stirring in an ice bath followed by hydrothermal treatment of the resulting dispersion (autoclave, 120 °C, 24 h), drying, and calcination in air (500‐700 °C, 2 h).

Lithium Adsorption on Magnetite, Lepidocrocite, and Maghemite at Elevated Temperatures

Lithium adsorption on the surface of magnetite, lepidocrocite, and maghemite particles was studied at different pH values in LiOH and Li2CO3 solutions under redox conditions and temperatures relevant to the water chemistry of CANadian Deuterium Uranium (CANDU) reactors. Lithium adsorption on maghemite shows a different behavior than on lepidocrocite and magnetite. It is concluded that specific adsorption is the dominant adsorption mechanism on maghemite while lithium adsorption on lepidocrocite and magnetite is nonspecific. However, lithium intercalation into the spinel structure of magnetite and maghemite is also likely. The introduction of O2 reduces lithium adsorption on magnetite. The adsorption behavior of lithium on iron oxides is important to understand the lithium hideout and return in the heat transport system during shutdown and restart of CANDU reactors.

Cobalt doping effects on photoluminescence, Raman scattering, crystal structure, and magnetic and piezoelectric properties in ZnO single crystals grown from molten hydrous LiOH and NaOH solutions

Transparent, olive-green single-crystal Zn1−xCoxO in the form of hexagonal lamellae grown from molten hydrous LiOH and NaOH solutions have been studied in terms of crystal structure, optical properties, Raman scattering, and magnetic and piezoelectric properties. Rietveld refinement shows that the lattice parameters and bond lengths decrease with increasing cobalt concentration. Cobalt doping results in slight changes to the piezoelectricity of ZnO, but leads to two new photoluminescence emission peaks at wavelengths of 443 and ∼510nm, along with the disappearance of certain Raman active modes. Furthermore, the ferromagnetic state is absent in all Zn1−xCoxO crystals, and they are all typically paramagnetic instead.

Enhancing the Long-Term Cyclability and Rate Capability of Li4Ti5O12 by Simple Copper-Modification

Cu-modified Li4Ti5O12 (LTO) with various Cu-doping contents was prepared via simple hydrolysis of tetrabutyl titanate in the water solution of LiOH·H2O and Cu(NO3)2·3H2O, followed by sintering the dried mixture at 600°C for 5h. By virtue of the slightly increased lattice constant, refined grains with relatively large surface area, improved electronic and ionic conductivities, the modified products exhibit excellent long-term cycling stability at a high current rate of 10C and outstanding rate performance at 0.1–40C. Particularly, the product with a Cu-doping content of 0.08 demonstrates prominent long-term cycling performance up to 2500 cycles at 10C and superior capacity retention even at 10–40C. The Cu-modified LTO could be used as efficient anode materials for long-life and high-rate lithium ion batteries.

Dilithium cyclohexanediacetate: A layered coordination polymer with non-valent hydrophobic contacts

By heating a solution of LiOH and 1,1′-cyclohexanediacetic acid (H2chda) coordination polymer [Li2(chda)] (1) having a layered nature is obtained and characterized.

Excellent Stability of a Lithium‐Ion‐Conducting Solid Electrolyte upon Reversible Li+/H+ Exchange in Aqueous Solutions

AbstractBatteries with an aqueous catholyte and a Li metal anode have attracted interest owing to their exceptional energy density and high charge/discharge rate. The long‐term operation of such batteries requires that the solid electrolyte separator between the anode and aqueous solutions must be compatible with Li and stable over a wide pH range. Unfortunately, no such compound has yet been reported. In this study, an excellent stability in neutral and strongly basic solutions was observed when using the cubic Li7La3Zr2O12 garnet as a Li‐stable solid electrolyte. The material underwent a Li+/H+ exchange in aqueous solutions. Nevertheless, its structure remained unchanged even under a high exchange rate of 63.6 %. When treated with a 2 M LiOH solution, the Li+/H+ exchange was reversed without any structural change. These observations suggest that cubic Li7La3Zr2O12 is a promising candidate for the separator in aqueous lithium batteries.

Excellent stability of a lithium-ion-conducting solid electrolyte upon reversible Li(+) /H(+) exchange in aqueous solutions.

Batteries with an aqueous catholyte and a Li metal anode have attracted interest owing to their exceptional energy density and high charge/discharge rate. The long-term operation of such batteries requires that the solid electrolyte separator between the anode and aqueous solutions must be compatible with Li and stable over a wide pH range. Unfortunately, no such compound has yet been reported. In this study, an excellent stability in neutral and strongly basic solutions was observed when using the cubic Li7 La3 Zr2 O12 garnet as a Li-stable solid electrolyte. The material underwent a Li(+) /H(+) exchange in aqueous solutions. Nevertheless, its structure remained unchanged even under a high exchange rate of 63.6 %. When treated with a 2 M LiOH solution, the Li(+) /H(+) exchange was reversed without any structural change. These observations suggest that cubic Li7 La3 Zr2 O12 is a promising candidate for the separator in aqueous lithium batteries.

ChemInform Abstract: Rapid Synthesis of LiFePO4 by Coprecipitation.

AbstractLiFePO4 nanoplates as cathode material for rechargeable lithium ion batteries are prepared by coprecipitation from ethylene glycol solutions of LiOH·H2O, FeSO4·7H2O, and H3PO4 with a molar ratio of 3:1:1.

The dielectric properties response of aqueous LiOH solution at the microwave frequency

In this paper, we investigate the dielectric properties of aqueous LiOH solution over frequency range 20 MHz~20GHz. The system behavior is well described according to four Cole–Cole (CC) terms whose evolution with composition is analyzed. Applying the extended Froehlich theory, we reveal the dual nature of water–ion and water–dipole interaction and propose an overview of the effects that water–ion interaction plays a dominating role in the aqueous LiOH solution system. With the theoretical framework 3D trajectory model, we find only about one H-bonded water cluster relaxes during the cutoff relaxation time interval 8.9 ps. The decay of the effective number of water molecules bound to the ions with its concentration, and Li+ perturb the water structure beyond the first hydration shell which is confirmed in the aqueous LiOH solution system.

Water-stable lithium ion conducting solid electrolyte of iron and aluminum doped NASICON-type LiTi2(PO4)3

High lithium ion conductivity solid electrolytes of Li1.4FexAl0.4 - xTi1.6(PO4)3 (x = 0−0.4) with the NASICON-type structure were synthesized by using a sol−gel precursor. The highest electrical conductivity was obtained for Li1.4Fe0.25Al0.15Ti1.6(PO4)3 sintered at 1040 °C for 7 h in air. The total, grain boundary, and bulk conductivities of the pellet were 1.01 × 10-3, 2.17 × 10-3 and 1.81 × 10-3 S cm-1 at 25 °C, respectively. The contribution of electron (or hole) conductivity to the total conductivity was negligibly small. Li1.4Fe0.25Al0.15Ti1.6(PO4)3 was unstable in water, but stable in saturated LiOH and LiCl aqueous solutions.

Recovery of Lithium Cobalt Oxide Material from the Cathode of Spent Lithium-Ion Batteries

Inthispaper,anewprocessisdescribedforrecoveringLiCoO2 fromspentLIBsbymeansofultrasoundradiationunderhydrothermal condition. In order to achieve the best effects of recovery, the influence of different temperature and reaction time on the effects of repairing LiCoO2 Crystal Structure (in 2.0 M LiOH solution, ultrasonic power 800 W) was investigated and the function of ultrasonic irradiation in the reaction was discussed. The optimal temperature and time condition for the renovation process were 120 ◦ Ca nd 6 h, respectively. The initial charge and discharge capacity of renovated LiCoO2 were 132.8 and 131.8 mAh/g, respectively. After 40 cycles, the capacity had decreased by less than 2% compared with the first cycle, which could reach electrochemical properties of commercial batteries. This process involves simple equipment and could be feasible for recycling LIBs in large scale.