LiOH Aqueous Solution Research Articles

Synthesis and electrochemical performance of lithiated manganese oxides Li0.35MnO2 with tetragonal structure

Non-stoichiometric Li0.35MnO2 nanoparticles with tetragonal-structure were successfully synthesized from MnCl2·4H2O and KOH in LiOH aqueous solution, via chemical lithiation under liquid olefin atmosphere at 353K. The microstructure and composition of the nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, and inductively coupled plasma atom emission spectroscopy. The valence state of manganese in the sample was determined by the redox titration method. Further, the electrochemical performance of the sample as a cathode material was evaluated by galvanostatic measurements and cyclic voltammetry. The sample was found to exhibit a tetragonal structure with irregularly shaped grains, and grain diameters between 20 and 40nm. The t-Li0.35MnO2 prepared also exhibited high capacity as lithium ion cathode materials with an initial discharge capacity of 178.8mAhg−1 and retained the discharge capacity at 131.7mAhg−1 after 50 cycles.

VLE Modeling of Aqueous Solutions of Unloaded and Loaded Hydroxides of Lithium, Sodium and Potassium

This work focuses on equilibrium modeling of CO2 solubility in aqueous solutions of unloaded (as hydroxides) and loaded (as carbonates) hydroxides containing Li+, Na+ and K+ counter ions. Due to the ionic nature of the LiOH/NaOH/KOH-CO2-H2O solutions, the electrolyte-Non-Random-Two-Liquid (e-NRTL) model, described by Chen and Evans [1], is applied to correct the non-idealities in the liquid phase. The special feature of the equilibrium model employed in this work is the simultaneously regression of Vapor-Liquid Equilibrium (PCO2, Ptotal) and apparent Henry's law constant data selected from literature and Ptotal data for LiOH measured in this work. This approach will give better prediction for the molecular CO2 activity coefficients and the liquid phase activities calculated by use of the resulting e-NRTL model will be consistent with the apparent Henry's law constant. The equilibrium model developed in this work is based on and represented 112 data points for Li+ with 2.7% total AARD, 432 selected data points for Na+ with total 7.2% AARD and 354 selected data points for K+ with total 9.9% AARD. The total pressure data over aqueous LiOH solutions were measured for a range of concentrations (0.25 – 8.5wt. %) and temperatures (40 – 90°C) using an ebulliometer.

Effects of nonionic surfactant on the parasitic corrosion of lithium anode in lithium–water battery

The use of a nonionic surfactant, namely cocamide diethanol amine (CDA), as a parasitic inhibitor for lithium corrosion in 4.0 M LiOH aqueous solution has been evaluated in the 298–313 K temperature range.

Electrochemical Behavior of Electrolytic Manganese Dioxide in Aqueous KOH and LiOH Solutions: A Comparative Study

As an inexpensive and high capacity oxidant, electrolytic manganese dioxide (γ-MnO2) is of interest as a cathode for secondary aqueous batteries. Electrochemical behavior of γ-MnO2 was characterized in aqueous 5.0 M KOH and LiOH solutions, and found to depend strongly upon cation identity. In LiOH and mixed LiOH / KOH solutions, Li-ion intercalation appeared to operate in competition with proton intercalation, being favored at higher [Li+] and, for mixed electrolytes, lower sweep rates. Electrochemical and in situ X-ray diffraction data indicated that γ-MnO2 underwent a chemically irreversible transformation upon the first reduction in LiOH solution, while in KOH solution, structure was largely unchanged after the first cycle. These experiments with γ-MnO2 as well as with a closely-related, ramsdellite-like sample, suggest that depending on sample morphology/rate capability, the irreversible process proceeds either through a solid-solution reaction or a two-phase reaction followed by a solid-solution reaction. While discharge capacity and capacity retention during galvanostatic cycling of γ-MnO2 were worse in LiOH than in KOH solution, some improvement was noted in a mixed LiOH/KOH solution.

ChemInform Abstract: Synthesis of Garnet‐Type Li7La3Zr2O12 by Coprecipitation Method.

AbstractThe title compound is synthesized by calcination (air, alumina crucible, 950 °C, 10 h) of a mixture of LiOH·H2O and a precursor obtained by coprecipitation from an aqueous solution of LaCl3, ZrOCl2, and LiOH.

Synthesis of Lithium Titanate (Li4Ti5O12) through Hydrothermal Process by using Lithium Hydroxide (LiOH) and Titanium Dioxide (TiO2) Xerogel

Lithium Titanate (Li4Ti5O12) or (LTO) has a potential as an anode material for a high performance lithium ion battery. In this work, LTO was synthesized by a hydrothermal method using Titanium Dioxide (TiO2) xerogel prepared by a sol-gel method and Lithium Hydroxide (LiOH). The sol-gel process was used to synthesize TiO2 xerogel from a titanium tetra-nbutoxide/Ti(OC4H9)4 precursor. An anatase polymorph was obtained by calcining the TiO2 xerogel at a low temperature, i.e.: 300 o C and then the hydrothermal reaction was undertaken with 5M LiOH aqueous solution in a hydrothermal process at 135 o C for 15 hours to form Li4Ti5O12. The sintering process was conducted at a temperature range varying from 550 o C, 650 o C, and 750 o C, respectively to determine the optimum characteristics of Li4Ti5O12. The characterization was based on Scanning Thermal Analysis (STA), X-ray Powder Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) testing results. The highest intensity of XRD peaks and FTIR spectra of the LTO were found at the highest sintering temperature (750 o C). As a trade-off, however, the obtained LTO/Li4Ti5O12 possesses the smallest BET surface area (< 0.001 m 2 /g) with the highest crystallite size (56.45 nm).

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.

Zr–Sn–Nb–Fe–Si–O alloy for fuel cladding candidate: Processing, microstructure, corrosion resistance and tensile behavior

A Zr–Sn–Nb–Fe–Si–O alloy was prepared and its microstructure, corrosion properties, hydrogen pick-up, and mechanical behavior were investigated and correlated. Both the conventional rolled and annealed specimens (Group A) and the second β-quenched specimens (Group B) possess proper corrosion resistance and hydrogen pick-up capability within 200 days exposure in LiOH aqueous solution, which are related to the suitable chemical composition, partial recrystallized microstructure and fine second phase particles. Group A at 380°C has slightly larger ductility in elongation than that at room temperature, whilst the elongation of Group B at 380°C increases nearly twice of that at room temperature.

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.

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.

Study of the Reaction Mechanism of Aqueous Li-O2 Batteries

Li-O2 battery is one of the most expected electrochemical energy storage systems beyond lithium ion batteries, because of its high theoretical energy density. Most of the groups are working on the non-aqueous Li-O2 battery system whose discharge reaction is described in the equation (1).2Li+ + O2 + 2e ➔ Li2O2 (1)Even though recent studies proved that the reversibility of the reaction, there still remains a lot of fundamental problems before the development of a practical Li-O2 battery. Especially the overpotential of the air electrode during the charging process is an essential problem considering the energy efficiency of the battery system, hence a lot of research groups have been focusing on finding a new catalyst to reduce the overpotential. Besides these studies for the non-aqueous system, our group has been focusing on an aqueous Li-O2 battery system based on the reaction (2), because overpotential of the charge-discharge reaction is much lower than that of the non-aqueous one. 4Li ++ O2 + 2H2O + 4e ➔ 4LiOH (2)Since the reaction is well known as the cathode reaction of alkaline fuel cell, the detail of the reaction mechanism of aqueous Li-O2 battery has never been investigated recently. Previously we reported that the discharging product remaining at the surface of the air-electrode was NOT LiOH but Li2O2. We suspect that the saturated electrolyte solution hindered the hydrolysis of the Li2O2 formed during the discharging process resulting in the stabilization of the Li2O2 even in the aqueous electrolyte solution. In the present study we performed further investigation for the reaction mechanism of the aqueous Li-O2 battery, using various analytical tools such as XRD, SEM-EDX, FTIR and so forth. The electrochemical studies were carried out using a three-electrode cell consists of a gas-diffusion electrode as a working electrode, a Ag/AgCl reference electrode and a Pt/Pt-black counter electrode. The gas-diffusion electrode was prepared by mixing carbon black and PTFE powder and layered with a carbon paper. The electrolyte solution was 10 LiCl and saturated LiOH aqueous solution. The electrochemical tests were performed under pure O2. SEM images for an air-electrode after the discharging process showed flake-like deposits suggesting the formation of crystalline Li2O2. The deposits were mostly disappeared after the charging process. Furthermore, an XRD pattern for a charged electrode also showed that the Li2O2 completely disappeared after the charging process. However some side-reactions could have been taken place during the charging process, because small diffraction peaks corresponding to LiOH·H2O and Li2CO3 were observed. The possible side reactions for these products could be 1. a hydrolysis of Li2O2 for LiOH·H2O and 2. a decomposition of carbon electrode. In addition, the electrode potential observed in the charging-discharging test indicated that the actual electrochemical reaction is not based on oxygen-water couple but on oxygen-peroxide couple. Detailed discussions concerning the reaction mechanism will be held in the meeting.

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.

Corrosion-related defects in Zircaloys: a preliminary study with slow positron beam

Corrosion-related microstructure and defects in Zircaloy-4 and N18 alloys were investigated by variable energy positron annihilation spectroscopy. The specimens were corroded in 0.01mol/L LiOH aqueous solution at 360 °C/18.6 MPa and in super heated steam at 400 °C/10.3 MPa, respectively. Defect profiles were analyzed by measuring the S parameter as a function of incident positron energy from 0.25 to 27 keV. Results indicated that Zircaloys corroded in LiOH aqueous solution contained more defects in the oxide layer than that in superheated steam, which implies that formation of defects in oxide layer may relate to the effects of Li+ ions in corrosion solution.

ChemInform Abstract: An Unnoticed Inorganic Solid Electrolyte: Dilithium Sodium Phosphate with the Nalipoite Structure.

AbstractOrthorhombic Li2NaPO4 is synthesized by stirring aqueous solutions of LiOH, NaOH, and H3PO4 followed by drying at 700 °C in air overnight.

Novel Co-Precipitation Method for Synthesis of Carbon-Free LiFePO4

Lithium iron phosphate (LiFePO4) is an important alternative cathode material to LiCoO2, which applications are limited by resource availability and safety issues. However, the full potential of the material is sometimes difficult to achieve due to its limited electrical conductivity and low rate of Li+ ion diffusion that together may limit the battery performance. One strategy is to manufacture LiFePO4 particles coated with a conductive phase, such as carbon, which improves the electronic contact between the LiFePO4 particles. However, the carbon seems to modulate not only the electric conductivity but also the reduce crystallite sizes and thus reduces the distance for Li+ transport in the LiFePO4 structure. Furthermore, carbon may improve the phase purity of the final product because during high temperature synthesis, carbon acts as a reducing agent and thus minimizes the likelihood of oxidation of Fe2+ to Fe3+. Despite these advantages, the role of different forms of carbon on the synthesis of LiFePO4 and the electrochemical performance of the materials is yet to be fully understood. This could be because the synthetic methods reported in the literature employ carbon containing precursors or solvents and therefore the LiFePO4 product always contain some form of residual carbon. This complicates the analysis of the effect of a specific carbon type on the electrochemical performance of the cathode material.Carbon-free LiFePO4 material has been synthesised by a novel single-step co-precipitation method from aqueous solutions of LiOH∙H2O, NH4H2PO4 and FeSO4.7H2O precursors. The precipitation sequence and methodology, reaction atmosphere and the role of intermediate phases on the purity of LiFePO4 product has been investigated. The mechanism of formation of phase-pure carbon free LiFePO4 is also investigated and the role of synthesis atmosphere on the phase transformations and the effect of evolving gaseous species on the likelihood of oxidation of Fe2+ to Fe3+ are discussed. The lowest temperature to synthesise phase pure carbon-free LiFePO4 is 550 oC which remains phase pure during further heating up to 750 oC. The novel carbon-free method is suitable for investigation of the effect various forms of carbon (carbon black, nanotubes, meso-porous carbons, etc.) on the electrochemical performance of the cathodes containing LiFePO4.

Rechargeable aqueous lithium–air batteries with an auxiliary electrode for the oxygen evolution

A rechargeable aqueous lithium–air cell with a third auxiliary electrode for the oxygen evolution reaction was developed. The cell consists of a lithium metal anode, a lithium conducting solid electrolyte of Li1+x+yAlx(Ti,Ge)2−xSiyP3−yO12, a carbon black oxygen reduction air electrode, a RuO2 oxygen evolution electrode, and a saturated aqueous solution of LiOH with 10 M LiCl. The cell was successfully operated for several cycles at 0.64 mA cm−2 and 25 °C under air, where the capacity of air electrode was 2000 mAh gcathod−1. The cell performance was degraded gradually by cycling under open air. The degradation was reduced under CO2-free air and pure oxygen. The specific energy density was calculated to be 810 Wh kg−1 from the weight of water, lithium, oxygen, and carbon in the air electrode.

Conformal coating of ultrathin Ni(OH)2 on ZnO nanowires grown on textile fiber for efficient flexible energy storage devices

A highly flexible supercapacitor is fabricated through a simple solution-based method in which conformal ultrathin (2 nm) nickel hydroxide (Ni(OH)2) layer is deposited on vertically grown zinc oxide (ZnO) nanowires on a three-dimensional, highly conductive textile substrate. The conformal ultrathin Ni(OH)2 layer enables a fast and reversible redox reaction which improves the specific capacitance by utilizing the maximum number of active sites for the redox reaction, while vertically grown ZnO nanowires on wearable textile fibers effectively transport electrolytes and shorten the ion diffusion path. The Ni(OH)2 coated ZnO nanowire electrodes show a high specific capacitance of 3150 F g−1 in a 1 M LiOH aqueous solution. Moreover, the asymmetric electrochemical capacitors with Ni(OH)2-coated ZnO nanowires as the positive electrode and multiwall carbon nanotubes-textile as the negative electrode exhibit promising characteristics with a maximum power density of 110 kW kg−1, an energy density of 54 W h kg−1, and excellent cycling performance of ∼96% capacitance retention over 5000 cycles.

Electrode Property of Sintered Ceramic Based on CaMnO3 in LiOH Aqueous Solution

Sintered ceramics of Ca0.9A0.1MnO3-δ(A = La, Nd, Sm, Gd and Y) were studied on their cathode properties in LiOHaq. solution. After firing, the samples were obtained as high conductivity sintered (porous) materials composed of an orthorhombic perovskite-type phase. Next, charge discharge performances of the electrodes consisting of the sintered sample were investigated. The discharge capacity of Ca0.9Y0.1MnO3-δwas 185 mAh·g-1on the 1st cycling, and the 1st charging was possible by 130 mAh·g-1. However, the 2nd discharge capacity remarkably decreased to lower than 50 mAh·g-1. Considering no obvious charging property on the previous La-substituted sample of Ca0.9La0.1MnO3-δ, it would mean that change of the substituent for CaMnO3 affects the electrochemical property. The roll of lithium ions, the effect of the cut-off potential range on the cycle performance would be discussed leading to the charge/discharge results of the cell (-)Zn/LiOHaq./Ca0.9Y0.1MnO3-δ(+).

Improved electrochemical properties by lithium insertion into Co3O4 in aqueous LiOH solution

Co3O4 microspheres were synthesized by a simple hydrothermal treatment. The first-cycle charge–discharge tests were carried out between −0.6 and 0.6V vs. SCE. The pristine, discharged and recharged specimens were characterized by X-ray power diffraction and scanning electron microscopy. Cyclic voltammetry (CV) curves of Co3O4 at various concentrations in LiOH solution were investigated. The appearance of the two pairs of redox peaks indicated that two sets of faradaic reactions were involved in the redox reactions of Co3O4 to LiCoO2 and LiHCoO2.

Water-stable lithium ion conducting solid electrolyte of the Li1.4Al0.4Ti1.6−xGex(PO4)3 system (x=0–1.0) with NASICON-type structure

Abstract Solid ionic conductors composed of Li 1.4 Al 0.4 Ti 1.6 − x Ge x (PO 4 ) 3 (x = 0–1.0) with the NASICON-type structure were synthesized with a precursor prepared using the sol–gel method. The electrical conductivity was examined as a function of x in Li 1.4 Al 0.4 Ti 1.6 − x Ge x (PO 4 ) 3 at various sintering temperatures and for various sintering periods. The highest electrical conductivity was obtained for Li 1.4 Al 0.4 Ti 1.4 Ge 0.2 (PO 4 ) 3 sintered at 900 °C for 11 h in air. The total and bulk conductivities of the sintered pellet were 1.29 × 10 − 3 and 2.35 × 10 − 3 S cm − 1 at 25 °C, respectively. The grain boundary resistance of Li 1.4 Al 0.4 Ti 1.4 Ge 0.2 (PO 4 ) 3 was significantly increased to 552 Ω cm 2 from 12.2 Ω cm 2 by immersion in distilled water at 50 °C for one week, whereas the bulk resistance was not increased. However, no significant increase of the bulk and grain boundary resistance was observed after immersion in a saturated aqueous solution of LiOH and LiCl.