Advanced Materials Letters

The quick advancement of flexible energy storage gadgets has persuaded individuals to look for reliable electrodes with high mechanical flexibility and remarkable electrochemical performance. In the present study, we demonstrate a simple and scalable process to fabricate a flexible, light-weight, free-standing polyvinylidene fluoride-multiwalled carbon nanotubes (PVDF-MWCNT) composite paper, which can be specifically utilized as a flexible anode for lithium ion batteries (LIBs). The excellent binding of MWCNT with PVDF matrix, developed by a straightforward vacuum filtration process, provides sufficient structural integrity to the composite paper. The breaking strength of the PVDF-MWCNT composite paper so formed is found to be 3.5 MPa with strain to failure of 11.25%. The composite paper so developed shows a good cycle reversible charge capacity when used as anode in a standard Li-ion battery. The PVDF-MWCNT composite paper provides a novel pathway to large scale fabrication of flexible electrodes which can be used without conducting support of copper sheet. 

A nanocrystalline titania-based sulfonic acid material was prepared, characterized and used as an effective, efficient and re-usable catalyst for the synthesis of 2-amino-4-(2-(4-methylpiperazin-1-yl) quinolin-3-yl)-6-phenyl-4H-pyran-3-carbonitriles and 2-amino-4-(2-(4-methylpiperazin-1-yl)quinolin-3-yl)-6-(pyridin-4-yl)-4H-pyran-3-carbonitrile derivatives under solvent-free conditions.  This simple three component one-pot synthesis results in high yield products in 2 hours via conventional heating protocols.  The catalyst was characterized by XRD, TEM, SEM, BET and Raman spectroscopy. The catalyst was recycled 5 times and recorded a decrease of 10 % in catalytic activity making it cost effective for large scale production.

Lead-free pseudo-binary compounds (1-x)Ba(Fe1/2Nb1/2)O3–xBaTiO3; (0 ≤ x ≤ 1) have been synthesized at 1200°C using conventional ceramic technique and characterized by X-ray diffraction, scanning electron microscopy, dielectric and vibration sample magnetometer studies. The crystal structure of the compounds is found to be monoclinic with the space group P2/m except for BaTiO3 for which it is tetragonal (P4/mmm). The incorporation of BaTiO3 significantly reduces the dielectric loss and improve the frequency and temperature stability of the dielectric properties of Ba(Fe1/2Nb1/2)O3. Compound 0.25Ba(Fe1/2Nb1/2)O3-0.75BaTiO3 exhibited a low value of temperature coefficient of capacitance (< ±3%) in the working temperature range (up to +85°C), room temperature dielectric constant equal to 282 and low loss tangent (~10-2) which meets the specifications for “Z5D” of Class II dielectrics of Electronic Industries Association. Hence, this composition might be a suitable candidate for capacitor applications. Besides, magnetic studies indicated the possibility of magneto-electric coupling in the system.

The polycrystalline sample of 0.25Ba(Bi1/2Ta1/2)O3-0.75BaTiO3 was synthesized using conventional solid state reaction technique. XRD analysis indicated the formation of a single-phase orthorhombic structure. The SEM analysis shows the grain sizes to be 0.12 to mm. Complex electric modulus analyses suggested the dielectric relaxation to be of non-Debye type. Dielectric studies indicated the relaxor behavior of 0.25Ba(Bi1/2Ta1/2)O3-0.75BaTiO3. The correlated barrier hopping model was employed to explain the mechanism of charge transport in the system. The ac conductivity is found to obey the Jonscher’s power law. The nature of variation of dc conductivity with temperature suggested NTCR behavior with activation energy 0.36eV. The studied material can be a potential candidate for capacitor applications.