Effect of lithium thiocyanate addition on the structural and electrical properties of biodegradable poly(ε-caprolactone) polymer films

Polymer electrolyte films of biodegradable poly(ε-caprolactone) (PCL) doped with LiSCN salt in different weight ratios were prepared using solution cast technique. The effect of crystallinity and interaction between lithium ions and carbonyl groups of PCL on the ionic conduction of PCL:LiSCN polymer electrolytes was characterized by X-ray diffraction (XRD), optical microscopy, Fourier transform infrared spectroscopy (FTIR) and AC impedance analysis. The XRD results revealed that the crystallinity of the PCL polymer matrix decreased with an increase in LiSCN salt concentration. The complexation of the salt with the polymer and the interaction of lithium ions with carbonyl groups of PCL were confirmed by FTIR. The ionic conductivity was found to increase with increasing salt concentration until 15 wt% and then to decrease with further increasing salt concentration. In addition, the ionic conductivity of the polymer electrolyte films followed an Arrhenius relation and the activation energy for conduction decreased with increasing LiSCN concentration up to 15 wt%. UV–vis absorption spectra were used to evaluate the optical energy band gaps of the materials. The optical energy band gap shifted to lower energies with increasing LiSCN salt concentration.     

Study of biopolymer I-carrageenan with magnesium perchlorate

The green revolution has led to the study of biopolymer for development of polymer electrolyte for electrochemical devices. Cellulose acetate, pectin, chitosan, and carrageenan are some of the biopolymers. Biopolymer-based membrane for proton conduction and lithium ion conduction have developed and characterized by different techniques. But the study of biopolymer based on Mg²⁺ ion is rare in literature. So, biopolymer based on I-carrageenan with magnesium has been studied. I-carrageenan biopolymer membrane with different concentration of magnesium perchlorate has been prepared by solution casting technique. Developed biopolymer membrane have been characterized by X-ray diffraction analysis (XRD), FTIR, differential scanning calorimetry (DSC), and AC impedance techniques. Pure I-carrageenan has shown a conductivity value of 5.90?×?10^?5 S/cm. I-carrageenan membrane with 0.6 wt% of magnesium perchlorate has shown a conductivity of 2.18?×?10^?3 S/cm. A primary Mg²⁺ ion battery has been constructed and its performance is studied. XRD has been undertaken to study the amorphous/crystalline nature of the sample. I-carrageenan with 0.6 wt% of magnesium membrane has shown highest amorphous nature. FTIR study confirms the complex formation between polymer and salt. AC impedance technique has been used to study the conductivity of the samples.     

Synthesis and characterization of novel urethane cross-linked ormolytes for solid-state lithium batteries

A novel family of Li⁺-based organic/inorganic materials obtained by the sol–gel process is proposed. The compounds, named urethanesils, are obtained as thin, transparent, elastomeric and amorphous monolithic films. They incorporate solvating pendant methyl end-capped short poly(oxyethylene) chains which are covalently bonded to the silica backbone by means of urethane cross-links. The urethane linkages are formed by reacting 3-isocyanatepropyltriethoxysilane with hepta(ethylene glycol) methyl ether (HEGME). Li⁺ has been introduced in the urethanesils as lithium triflate (LiCF₃SO₃). Two compositions of salt have been considered: n=100 and 8, where n represents the molar ratio of (OCH₂CH₂) units per lithium ion. Infrared spectroscopy provides conclusive evidence that, although the oligopolyether chains of HEGME become less disordered upon formation of the inorganic network, the addition of salt induces disorder. The FTIR spectrum of the most concentrated urethanesil strongly suggests that the triflate ions are essentially coordinated in the material. The thermal and mechanical properties of the undoped and doped urethanesils have been investigated by DSC and DMTA. At 90°C, the highest ionic conductivity (approximately 10⁻⁶ Ω⁻¹ cm⁻¹) is observed for composition n=8. The electrochemical stability domain of the least concentrated urethanesil spans 5 V.     

Manifestation of the specific structural features of lithium niobate single crystals of different composition in their Raman spectra

The Raman spectra of nominally pure lithium niobate single crystals of congruent, close to stoichiometric, and stoichiometric compositions and congruent lithium niobate single crystals doped with Gd³⁺, Y³⁺, and Mg²⁺ ions have been investigated. Weak lines whose widths anomalously decrease with an increase in cation sublattice disordering at a change in the single crystal composition were found for the first time. These lines may be indicative of fine ordering processes involving structural units of the cation sublattice, as a result of which this sublattice is disordered as a whole.     

Tamarind seed polysaccharide biopolymer membrane for lithium-ion conducting battery

Solid biopolymers have gained much attention in the development of polymer electrolytes due to its biocompatibility, film-forming nature, and non-toxicity. In the present work, biopolymer membrane has been prepared using tamarind seed polysaccharide (TSP) as host polymer and various concentrations of lithium chloride (LiCl) salt as dopant by solution casting technique. The prepared biopolymer electrolyte has been characterized by XRD, FTIR, differential scanning calorimetry (DSC) analysis, AC impedance spectroscopy analysis, and transference number measurement. XRD analysis has been done to investigate the amorphous/crystalline nature of the polymer membrane. The highest amorphous nature has been found for 1 g of TSP with 0.4 g LiCl. FTIR spectrum analysis confirms the complex formation between TSP biopolymer with LiCl. From AC impedance conductivity analysis, the maximum ionic conductivity is of the order of 6.7?×?10^?3 S cm^?1 at room temperature for 1 g TSP with 0.4 g LiCl, whereas for pure TSP biopolymer membrane, the ionic conductivity is of the order of 5.48?×?10^?7 S cm^?1. The glass transition temperature for the highest conducting biopolymer membrane for the composition of 1 g TSP: 0.4 g LiCl has been found to be 44.25 °C using the DSC technique. Employing the maximum conducting biopolymer membrane, a lithium-ion conducting battery has been fabricated and its discharge characteristics have been studied.     

Ab initio study of synergetic effects of two strong interactions of cation–π interaction and lithium bond in M+ ··· phenyl lithium ··· N (M = Li,Na, K; N = H2O and NH3) complex

Quantum chemical calculations have been performed to investigate the interplay between the cation–π interaction and lithium bonding in the M⁺?···?phenyl lithium?···?OH₂ and M⁺?···?phenyl lithium?···?NH₃ (M?=?Li, Na, K) complexes. The cation–π interaction and lithium bonding in the trimers become stronger relative to the dimers. The interaction energy of cation–π interaction is increased by about 4.4–6.3%, while that of lithium bonding is increased by about 5.2–15.9%. The cooperative energy becomes larger for the stronger cation–π interaction and lithium bond. The F atom and methyl group in the phenyl ring impose a reverse effect on the cation–π interaction and lithium bond. The interaction mechanism in the complexes has been understood with the many-body interaction analysis, electrostatic potentials, and energy decomposition.     

Tamarind seed polysaccharide (TSP)-based Li-ion conducting membranes

Polysaccharide-based biopolymers have gained much attention in electrochemical devices recently. Tamarind seed polysaccharide (TSP) is a biopolymer obtained from the extract of tamarind seed. It is used as thickening and gelling agent in food and textile industries. There are no works in polymer electrolytes based on TSP in lithium-ion conducting membranes. A pure TSP membrane has been prepared by dissolving 1 g of TSP in distilled water by using solution-casting technique. The prepared biopolymer membranes are subjected to Fourier transform infrared (FTIR), X-ray diffraction (XRD), and AC-impedance techniques. FTIR analysis has been conducted to observe the possible interaction between the polymer and lithium salt based upon the changes in wave numbers of the peaks. The nature of the membrane (crystalline or amorphous) has been revealed by XRD. The electrical properties of the membranes have been analyzed by AC-impedance spectroscopy. The maximum ionic conductivity for the salt-doped membrane 1 g TSP:0.4 g lithium bromide (LiBr) has been found to be 4.83 × 10^?4 S cm^?1. The primary lithium-ion battery has been constructed using the best conductivity membrane, and the open circuit voltage (OCV) has been observed as 1.63 V.     

Luminescence properties of α-Al2O3 dosimetric crystals exposed to a high-current electron beam

The spectra of pulsed cathodoluminescence (PCL) and thermoluminescence (TL) in TLD-500 detectors, which were exposed to a strong beam from a pulsed electron accelerator, have been studied. Additional bands in the PCL spectrum and new peaks in the TL curves, which are due to impurity ions, have been revealed. Luminescence bands of F- and F⁺-centers cannot be used in the dosimetry of strong electron beams using TLD-500 detectors because of the saturation of dose dependence and the decrease in the TL yield. It is shown that high doses from these beams can be measured by recording TL in the luminescence band of impurity titanium ions.     

Luminescence decay kinetics of Eu<Superscript>3+</Superscript> ions in phosphate glasses of different composition under photo- and electron excitations

The influence of matrix composition, coactivators, and excitation method on the luminescence kinetics of Eu³⁺ ions in lithium–phosphate and lithium–phosphate–borate glasses activated by Eu, Eu/Tb, and Eu/Dy is studied. Luminescence is excited by a high current electron beam and a xenon lamp. It is found that, under photoexcitation, the europium luminescence decays more slowly than under electronic excitation. Depending on the content of cation modifiers ZnO and Li₂O, the decay time decreases with increasing amount of ZnO. The decay time weakly depends on the europium concentration. The decay of the luminescence of europium ions is well described by the Inokuti–Hirayama model.     

PAN为基凝胶聚合物电解质自扩散系数的NMR研究

利用脉冲梯度场NMR方法直接测量了不同温度下的不同组分的PAN为基凝胶聚合物电解抽PAN-EC/PL-LiClO₄中锂离子的自扩散系数D.结果表明,锂离子的自扩散系数D依赖于锂盐质量分数x％,关且在x从5到20范围内,x=10时D有最大值.这与锂离子跳跃的传输机制及同时受到增塑剂EC与聚合物PAN网络的相互作用有关. 关键词：     

Lithium ion transport and ion-polymer interaction in PEO based polymer electrolyte plasticized with ionic liquid

The polyethylene oxide (PEO) based lithium ion conducting polymer electrolytes complexed with lithium trifluoromethanesulfonate (LiCF₃SO₃ or LiTf) plasticized with an ionic liquid 1-ethyl 3-methyl imidazolium trifluoromethanesulfonate (EMITf) have been reported. Morphological, spectroscopic, thermal and electrochemical investigations demonstrate promising characteristics of the polymer films, suitable as electrolyte in various energy storage/conversion devices. Significant structural changes have been observed in the polymer electrolyte due to the ionic liquid addition, investigated by X-ray diffraction (XRD) and optical microscopy. The ion-polymer interaction, particularly the interaction of imidazolium cation with PEO chains, has been evidenced by IR and Raman spectroscopic studies. The optimized composition of the polymer electrolyte i.e. PEO_25.LiTf + 40 wt.% EMITf offer room temperature ionic conductivity of ~ 3 × 10^− 4 S cm^− 1 with wide electrochemical stability window and excellent thermal stability. The ‘σ versus 1/T’ curves show apparent Arrhenius behavior below and above melting temperature. The ionic conductivity has been observed due to Li⁺ ions, as confirmed from ⁷Li-NMR studies, though the component ions of ionic liquid and anions also contribute significantly to the overall conductivity.     

固体核磁共振研究单斜磷酸钒锂的进展(英文)

在过去的二十年里,单斜型磷酸钒锂作为一种有前景的锂离子电池正极材料被广泛研究.固体核磁共振技术是一种研究原子局部环境和运动性,并能反映材料中长程/短程有序结构变化的有力表征手段,可以从多个角度满足磷酸钒锂材料的研究需求.本文从充放电机理、锂离子的迁移率和动力学、碳包覆、阳离子掺杂等方面简要介绍了固体核磁共振技术在单斜磷酸钒锂正极材料研究中的应用,同时涵盖了相关的理论计算工作.     

A quantum-chemical study on ion complexation in polymer electrolytes containing lithium aluminate salts

A quantum-chemical study on single-ion conducting electrolytes based on lithium aluminate salts is presented. Geometry optimizations for salts and corresponding anions have been performed. Stabilization energies for Li⁺ complexed at aluminate anions have been calculated. Information about Li⁺ coordination changes has been obtained from Born–Oppenheimer Molecular Dynamics simulations. Complexation energies for lithium cation have been shown to correlate with experimental conductivity values [T. Fujinami, Y. Buzoujima, J. Power Sources 119–121 (2003) 438].     

Impact of insoluble starch remnants on the behavior of corn starch/glycerol/LiCl solid electrolyte

The effect of starch-insoluble remnants (i.e., ghosts) on the behavior of the solid biopolymer electrolyte remains to be studied. This work focused on this issue by considering a case-study system formed by corn starch, glycerol, and lithium chloride. The ghost content was controlled by subjecting the gelatinized dispersion to ultrasonic cavitation at various times. Ghost content reduction led to a slight decrease in conductivity. When the ghost content was reduced to almost nil, the capacitance estimated from cyclic voltammetry tests showed a decrease of about 37%. In contrast, the stability of the electrolyte, estimated by repeated potential cycles, was positively affected. Formation of free radicals and starch chain retrogradation are postulated as the mechanisms involved in the conductivity and capacitance variations in corn starch, glycerol, and lithium chloride solid biopolymer electrolyte.     

掺镱锂硅酸盐玻璃的光谱及离子交换特性分析

采用高温二次化料的方法制备一种多梯度折射率芯光纤所用掺镱锂硅酸盐玻璃,测量了玻璃样品的吸收光谱、荧光光谱和荧光寿命,利用McCumber理论计算了该玻璃系统中镱离子的2F5/2→2I7/2能级跃迁受激发射截面。研究表明锂硅酸盐玻璃中Yb3+在1006nm处的σemi为0.38×10-20 cm2,荧光有效线宽为82.4nm,荧光寿命为1.31ms。在530℃高温硝酸钠熔盐中,对玻璃Li+-Na+离子交换到达中心轴前后制作的梯度折射率透镜的成像和折射率分布特性进行了研究。光谱分析和离子交换实验结果表明,该玻璃是制作梯度折射率光纤的理想材料,可用于多梯度折射率芯光纤的制作,是大模场光纤的候选材料。     

Self-diffusion of lithium,hydrogen, and oxygen ions in crystalline lithium hydroxide

The self-diffusion coefficients of ions of the three chemical elements forming lithium hydroxide have been determined by the crystal-crystal and crystal-gas isotope exchange method in the temperature range 500–720 K. Crystal samples with different isotope compositions have been grown by the Bridgman method from melts. The melting temperature is 743 ± 2 K. Original methods have been developed for high-precision measurements of the isotope ratios of all three elements, i.e., lithium (⁶Li/⁷Li), hydrogen (H/D), and oxygen (¹⁶O/¹⁸O), and their changes after diffusion annealings with the use of the same sample. The self-diffusion coefficients of lithium and hydrogen ions differ but by a factor of no more than 3–5; however, their values exceed those for oxygen by several orders of magnitude. In particular, at 670 K, they are equal to 6.0 × 10⁻⁹, 3.2 × 10⁻⁹, and 2.0 × 10⁻¹² cm² s⁻¹ for hydrogen, lithium, and oxygen, respectively. In the range 680–720 K, the self-diffusion coefficients of hydrogen and lithium increase sharply with increasing temperature to approximately 10⁻⁶ cm² s⁻¹. A probable mechanism of migration of protons and lithium ions in LiOH and the role played in this process by the oxygen ions with a lower mobility have been discussed.     

Growth and characterization of metal ions doped l-serine NLO single crystals for optoelectronic applications

Single crystals of pure and metal ions (K⁺, Na⁺ and Li⁺) doped l-serine have been grown by slow evaporation solution growth technique (SEST). Energy dispersive X-ray analysis (EDAX) and inductively coupled plasma optical emission spectroscopy (ICP-OES) prove the incorporation of metal ions into the doped crystals. The lattice parameters have been obtained from single crystal X-ray diffraction (XRD) studies. The presence of functional groups is identified by Fourier transform infrared (FTIR) and FT-RAMAN analyses. The thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) reveal that the thermal stability of lithium doped l-serine crystal is enhanced. The mechanical properties have been studied by vicker's microhardness test. UV–vis-NIR spectroscopy shows that the percentage of transmission is increased in lithium doped l-serine crystals. Potassium and lithium ions doped l-serine crystals have enhanced second harmonic generation (SHG) efficiency indicating that these crystals are potential candidates for non linear optical (NLO) applications.     

On the conversion of NDP energy spectra into depth concentration profiles for thin-films all-solid-state batteries

A three-step numerical procedure has been developed, which facilitates the conversion of NDP energy spectra into lithium concentration depth profiles for thin-film Li-ion batteries. The procedure is based on Monte Carlo modeling of the energy loss of charged particles (ions) in the solid media, using the publically available SRIM/TRIM software. For the energy-to-depth conversion, the battery stack has been split into finite volume elements. Each finite volume element becomes a source of ions according to the employed nuclear reaction. Ions loos energy when they move across the battery stack towards the detector. The as-obtained simulated spectra have been compared with the experimentally measured spectra. The thicknesses of the battery stack layers were estimated by minimizing the deviation between the simulated and measured spectra. Subsequently, a relation between the average energy of detected ions and the depth of the corresponding finite volume element, yielding a calibration function, was used to relate that particular part of the spectra with the depth of its source. At the final stage, a Bayesian estimator was used to find the distribution of lithium at a particular depth. The developed procedure was applied to a practically relevant case study of Si immobilization in the LPO electrolyte of all-solid-state thin-film batteries. It is shown that the lithium immobilization process in the LPO electrolyte is responsible for the battery degradation process.     

Biopolymer electrolytes based on carboxymethyl ҡ-carrageenan and imidazolium ionic liquid

Novel biopolymer electrolytes based on carboxymethyl kappa-carrageenan (CM?-carrageenan) and ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) have been successfully developed. Strong coordination and hydrogen bonding interaction of [Bmim]Cl with the biopolymer were detected by Fourier transform infrared (FTIR) spectroscopy. The efficient function of [Bmim]Cl as the charge carrier in the system was reflected by electrochemical impedance spectroscopy (EIS) where the highest ionic conductivity (σ) of (5.76 ± 0.20) × 10^?3 S cm^?1 was achieved at ambient temperature (298 K) upon 30 wt.% of [Bmim]Cl inclusion. X-ray diffraction (XRD) analysis confirmed that the addition of ionic liquid did not alter the prominent amorphous phase of CM?-carrageenan. Analysis of scanning electron microscopy (SEM) proved the strong interaction of [Bmim]Cl with the biopolymer matrix. The highest conducting biopolymer electrolyte showed an electrochemical stability up to 3.0 V, whereas the transference number measurement revealed that ions are the major elements that contribute to the conductivity with 0.970 ion transference number.     

Lifetime measurements of metastable states in Fe+

The lifetime of two metastable levels in Fe+ has been measured by laser probing of a stored ion beam. In the dense spectrum of Fe+, the metastable levels a (6)S(5/2) and b (4)D(7/2) were selected and their lifetimes were determined to be 230 +/- 30 and 530 +/- 30 ms, respectively. The lifetimes are compared with previous theoretical results. Metastable lifetime measurements of Fe+ are of great importance for interpretation of spectra from astronomical objects. The present experiment opens for the possibilities to investigate lifetimes of metastable states in complex atomic ions, which have, so far, been unexplored.