Amount Of Lithium Perchlorate Research Articles

Development of Polymer Blend Electrolyte Membranes Based on Chitosan: Dextran with High Ion Transport Properties for EDLC Application.

Solid polymer blend electrolyte membranes (SPBEM) composed of chitosan and dextran with the incorporation of various amounts of lithium perchlorate (LiClO4) were synthesized. The complexation of the polymer blend electrolytes with the salt was examined using FTIR spectroscopy and X-ray diffraction (XRD). The morphology of the SPBEs was also investigated using field emission scanning electron microscopy (FESEM). The ion transport behavior of the membrane films was measured using impedance spectroscopy. The membrane with highest LiClO4 content was found to exhibit the highest conductivity of 5.16 × 10−3 S/cm. Ionic (ti) and electronic (te) transference numbers for the highest conducting electrolyte were found to be 0.98 and 0.02, respectively. Electrochemical stability was estimated from linear sweep voltammetry and found to be up to ~2.3V for the Li+ ion conducting electrolyte. The only existence of electrical double charging at the surface of electrodes was evidenced from the absence of peaks in cyclic voltammetry (CV) plot. The discharge slope was observed to be almost linear, confirming the capacitive behavior of the EDLC. The performance of synthesized EDLC was studied using CV and charge–discharge techniques. The highest specific capacitance was achieved to be 8.7 F·g−1 at 20th cycle. The efficiency (η) was observed to be at 92.8% and remained constant at 92.0% up to 100 cycles. The EDLC was considered to have a reasonable electrode-electrolyte contact, in which η exceeds 90.0%. It was determined that equivalent series resistance (Resr) is quite low and varies from 150 to 180 Ω over the 100 cycles. Energy density (Ed) was found to be 1.21 Wh·kg−1 at the 1st cycle and then remained stable at 0.86 Wh·kg−1 up to 100 cycles. The interesting observation is that the value of Pd increases back to 685 W·kg−1 up to 80 cycles.

Preparation of polymer electrolyte membranes with continuous PEG channel via the fusion of self-assembled polycyclooctene-graft-polyethylene glycol copolymer micelles

Small molecular weight polyethylene glycol (PEG 350 g/mol) based polymer electrolyte membranes (PEMs) with continuous lithium ion transport channels are prepared via the fusion of the self-assembled micelles of amphiphilic copolymer. The self-assembled micelles consisted of nonpolar polycyclooctene (PCOE) core and polar PEG shell are formed via dialyzing the dichloromethane solution of amphiphilic polycyclooctene-graft-polyethylene glycol (PCOE-g-PEG) copolymer with ethanol, which is a good solvent for PEG and nonsolvent for PCOE. The resulted electrolyte membrane with bicontinuous morphology is obtained by casting the self-assembled micelle solution in a stainless steel plate and heating at 80 °C for 24 h after mixing with a certain amount of lithium perchlorate (LiClO4). When the content of PEG is 20 wt%, the ion conductivity of the self-assembled PEM can exceed 10−4S/cm at 25 °C, which is 3 orders of magnitude higher than the counter PEM groups prepared via directly casting of the copolymer dichloromethane solution without self-assembled process. While the mechanical strength of the self-assembled PEMs is almost the same as those directly casting ones, in which only PCOE phase is continuous.

Regioselective reduction of 2-perfluoroalkanoylcyclohexane-1,3-diones and their enamino derivatives

Ionic hydrogenation of 2-perfluoroalkanoylcyclohexane-1,3-diones and their endocyclic enamino derivatives containing a secondary amino group by the action of triethylsilane in trifluoroacetic acid in the presence of a catalytic amount of lithium perchlorate involved regioselective reduction of the side-chain carbonyl group to hydroxy with formation of the corresponding hydroxy diketones and hydroxy amino ketones, respectively. Under analogous conditions endocyclic enamino derivatives possessing a tertiary amino group underwent deacylation to give enamino ketones.

Solvent-Free Thiolysis of Epoxides under Lithium Perchlorate Catalysis

Solvent-free ring opening of 1,2-epoxides with thiols using catalytic amounts of lithium perchlorate affords high yields of β-hydroxy sulfides. Nucleophilic attack of the thiols occurs regioselectively at the sterically less hindered side of the epoxides.

LiClO4‐Catalyzed Highly Diastereoselective Synthesis of cis‐Aziridine Carboxylates.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Molecular interactions in polyacrylamide/lithium perchlorate hydrogel composites

In this study, the effects of introduction of lithium perchlorate into polyacrylamide hydrogels having constant amounts of acrylamide monomers and N,N′-methylene-bis-acrylamide crosslinker have been studied through the observed changes in the vibrational Raman spectra. The changes in the perchlorate anion's Raman modes show that in the polymeric matrix most of the lithium and perchlorate ions are separated by the polyacrylamide coils. The changes in the Raman modes of the polymeric chains show that the interactions of the two ionic species with the coils are unfavourable to the hydrogen-bond network of the hydrogel matrix. As the amount of lithium perchlorate in the hydrogel increases the role played by the intra and inter-molecular hydrogen bonds due either to the amide groups or the interstitial water decreases; the amide groups become more accessible to chemical transformations and the hydrogel flexibility increases.

Polyphosphazene Electrolytes. 2. Synthesis and Properties of New Polymer Electrolytes Based on Poly((amino)[(2-methoxyethoxy)ethoxy])phosphazenes

A series of ether group and amino group cosubstitutent phosphazene copolymers was synthesized and characterized by a combination of NMR, elemental analysis, and FTIR spectroscopy. The length of the alkyl group in the amino side chain and the content of the methoxyethoxyethoxy (MEE) substituent on the polymer properties were varied. Dynamic mechanical analysis (DMA) demonstrated that the cosubstitutent polymers prepared have better mechanical properties than the ether homopolyphosphazene, poly[bis(2-methoxyethoxy)ethoxy]phosphazene, MEEP. The copolymers that possessed multiple electron-donor coordination sites, nitrogen and oxygen atoms, were complexed with various amounts of lithium perchlorate (LiClO4) to form polymer electrolytes. The ionic conductivity of the polymer electrolytes were determined by an impedance analyzer in a temperature range of 30−80 °C. According to those results, the conductivities of the prepared polymer electrolytes increased according to the rise in the MEE side chain contents and reached optima at F = 0.2−0.25. The best conductivity obtained is 2.2 × 10-5 S/cm for CPE-3A with F = 0.25.

Vibrational spectroscopic studies of interactions between LiClO 4 and the plasticizer dimethylformamide

The Raman and infrared (IR) spectra of dimethylformamide (DMF) containing different amounts of lithium perchlorate have been recorded and analyzed, respectively. It has been found that the Li + ions interact with both the nitrogen atom in the quaternary ammonium structure and the oxygen atom in the CO group of DMF. The activation of the IR-forbidden v 1 mode and the splitting of the v 4 mode of ClO 4 − anions indicate that ion aggregates are formed at low LiClO 4 concentration. The results of the IR spectroscopic measurements also suggest that the ionic aggregation in the LiClO 4-DMF system may have its own characteristics.

A mechanism of ionic conduction of poly (vinylidene fluoride)-lithium perchlorate hybrid films

Polymeric solid electrolytes were prepared by the hybridisation of poly(vinylidene fluoride) and lithium perchlorate. These were obtained as films of about 0.1 mm thickness, and showed high lithium ionic conductivity of about 10 −5 (S cm −1). The conductivity depended on the contents of lithium perchlorate and polar additives having high boiling temperature. The amount of lithium perchlorate and the logarithm of the conductivity showed linear relation up to a certain (critical) amount of lithium perchlorate. Beyond the critical value, crystals of lithium perchlorate grew in polymer matrix, and the conductivity was not increased so much. Viscosity and dielectric constant of the additives were potent factors to increase the conductivity of the hybrid film. Organic polar materials with lower viscosity such as N, N-dimethyl formamide or γ-butyrolactone strongly contributed to the improvement of lithium ionic conductivity. The activation energy of conduction decreased dramatically by increasing mole ratio of additive and lithium perchlorate. The lithium ions were considered to migrate in the conduction path which was formed by polymer matrix with organic additive molecules.