Exploration on sulfur/acid treatment of sepiolite composite positive electrode material for lithium-sulfur battery

High energy density battery system is endowed with more complex Lithium sulfur cathode whose electrochemical redox reaction and phase transition occurred due to multi electron participation. The different mole ratios of sepiolite mixed with sulfur were synthesized by acid cum thermal treatment method. The morphological analysis illustrates that the sepiolite powder is composed of micro fibrous bundles in the range of 1 μm to 10 μm. The sorption isotherms indicate that the sieved sepiolite (Sp) and different mole ratio (4, 6 and 8) of sepiolite/sulfur shows a type-IV isotherm of mesoporous material. The S/SvSp (sulfur/sieved sepiolite) composite cathode exhibits an initial discharge capacity of 1066 mAh g^?1 and attains a stable capacity of 596 mAh g^?1 during 40 cycles with 97% of efficiency. All the results correlated with the better electrochemical behaviour of electrode and it satisfies the needs of high energy density storage application.     

Sulfur/PAN/acetylene black composite prepared by a solution processing technique for lithium–sulfur batteries

A sulfur/poly(acrylonitrile)–PAN/acetylene black–AB composite, comprising sulfur and PAN encapsulated in the pores of AB was prepared by a solution‐based technique with dimethyl sulfoxide as the solvent. The composite was characterized by TGA, X‐ray diffraction, FTIR, Raman, SEM, TEM, and BET studies. The composite exhibited a high discharge capacity of 1330 mAh/g in the first cycle. The AB additive plays multiple roles in the composite, acting as a conducting matrix for electron transport and as a porous framework that adsorbs and retains electrolyte. The presence of PAN along with the porous carbon matrix in the composite provides the necessary resilience to absorb strains due to volume expansion during cycling. The observed improved performance of the composite is primarily attributed to the small size and homogeneous distribution of sulfur in the composite. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46598.     

Studies on the effect of anions of various lithium salts in PEMA gel polymer electrolytes

This research synthesized graft copolymers of chitosan‐g‐poly(N‐isopropyl acrylamide) (CS‐g‐PNIPAAm) by UV‐initiated free‐radical polymerization of NIPAAm monomer to CS selectively at the C‐6 position of pyranose ring. First, amino groups in CS were protected by reaction with phthalic anhydride (PA) to form PACS. The degree of phthaloylation was carefully controlled to ensure that most amino groups were protected, and only a very small amount of hydroxyl groups were reacted. In the second step, the vinyl functional group was introduced to the PACS by reaction with a vinyl compound containing an isocyanate group (3‐isopropenyl‐αα′‐dimethylbenzyl isocyanate), through the urethane linkage with hydroxyl groups at the C‐6 position. The phthaloyl groups were then removed by hydrazine to recover the amino groups in CS. Finally, PNIPAAm was grafted to the vinyl CS at the C‐6 position by UV‐initiated free‐radical polymerization. The synthesized CS‐g‐PNIPAAm copolymers were confirmed to have a structure of an AB‐crosslinked graft copolymer. Respectively, these copolymer hydrogels exhibited pH‐ and thermal‐responsive swelling properties in an aqueous solution due to their CS and PNIPAAm components. The test of cell viability with L929 fibroblast revealed that the CS‐g‐PNIPAAm copolymers having a grafting ratio lower than 1.7 had cellular compatibility as good as pure CS. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electrochemical investigations on the effect of dispersoid in PVA based solid polymer electrolytes

Various compositions of TiO₂ dispersed PVA‐PMMA‐LiBF₄‐EC based electrolytes were prepared using solution casting technique. The prepared electrolytes were characterized using AC impedance, XRD, SEM, FTIR, etc. The ionic conductivity value is increased with the increase in filler content (up to 8 wt %) and then decreased with the increase in filler content. The results are described using Vogel–Tamman–Fulcher theory. The thermal and transport properties of the electrolyte exhibiting maximum conductivity have also been studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3950–3956, 2007     

Influence of the concentration of capping agent on synthesizing and analyses of Ceria nano-filler using modified co-precipitation technique

The pure crystalline cerium oxide (CeO₂) nanoparticles were synthesized using optimized content of Ce(NO₃)₃. 6H₂O with varying concentrations of sodium hydroxide (NaOH) (0.5, 1, 1.5, and 2 M) as a precipitation agent in presence of 2.5 wt% poly(vinylpyrrolidone) PVP. All the samples are prepared via the modified coprecipitation technique. The synthesized materials have been analyzed using X-ray diffraction (XRD), Fourier transform infrared (FT-IR), laser Raman, high-resolution scanning electron microscope (HR-SEM), and photo luminescence (PL) analyses. The optimized sample was identified with the help of the above studies that could be analyzed through transverse electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) studies. The cubic structure with the Fm-3 m space group has been confirmed through XRD (JCPDS: 81-0792) and Raman analyses. The FT-IR and energy dispersive X-ray spectroscopy (EDX) analyses ascertain the occurrence of Ce and O species. The as-prepared CeO₂ filler (0, 3, 6, 9, and 12 wt%) is dispersed through the optimized polymer electrolyte Poly (styrene-co-methyl methacrylate) P(S-MMA) (27 wt%)–lithium perchloride (LiClO₄) (8 wt%)–ethylene carbonate + propylene carbonate (EC + PC) (1;1 of 65 wt%) complex system using solution casting technique. P(S-MMA) (27 wt%)–LiClO₄ (8 wt%)–EC + PC (1;1 of 65 wt%)–6 wt% of CeO₂ shows the high ionic conductivity 8.13 × 10⁻⁴ S cm⁻¹.     

Cobalt-doped layered lithium nickel oxide as a three-in-one electrode for lithium-ion and sodium-ion batteries and supercapacitor applications

Layered LiNi_0.94Co_0.06O₂ (LNCO) was prepared and explored as an energy-storage material for Li-ion (LIBs), Na-ion (SIBs) batteries as well as supercapacitor application for the first time. All the physical and morphological characterizations were studied for the sample LNCO. The result displays good thermal stability, phase purity in the crystal structure, appreciable Brunauer-Emmett-Teller (BET) surface area (5.53 m² g⁻¹) and possesses cubic morphology. The cobalt was identified in lithium nickel oxide with binding energies at 794.02, 779.04 and 784.30 eV, respectively. In the case of LIBs, LNCO exists with a minimal difference of 5 mAh g⁻¹, even when cycled from 2C to 0.1C. After 200 cycles, the specific capacity, 247 mAh g⁻¹, is obtained for the cell with retention of 97.8% (efficiency 99.8%) at 0.1C. In SIBs, at 0.1C, the discharge capacity of 182 mAh g⁻¹ was restored even when cycled after 2C. After 200 cycles, a discharge capacity of 204 mAh g⁻¹ is ensured with retention of 96.6% (efficiency of 99.4% at 0.1C). In supercapacitor, the electrode, LNCO, delivered a specific capacity of 300 F g⁻¹ at 0.5 A g⁻¹. Therefore, LNCO is highly recommended as a suitable electrode material for fulfilling the requirement of energy-storage applications.     

A study on high rate and high stable sodium vanadium phosphate electrode for sodium battery alongside air exposure treatment

Journal of Materials Science: Materials in Electronics - The compound Na3V2(PO4)3/C (NVP) is an identical prevalent cathode for sodium-ion batteries (SIBs) because of its high Na+-ion mobility and...     

Electrochemical analyses of ZrO2 dispersoid incorporated poly (styrene-methyl methacrylate) blend gel electrolytes for lithium-ion battery

Zirconium oxide (ZrO₂) filler is successfully synthesized with spherical morphology (particle size 170 nm) by co-precipitation technique earlier. The as-prepared ZrO₂ -(bare, 3, 6, 9, and 12 wt%) is spread into the augmented poly(styrene-co- methyl methacrylate) P(S-MMA)- poly vinylidene fluoride (PVdF) (25:75 of 27 wt%)-LiClO₄ (8 wt%)- ethylene carbonate and propylene carbonate (EC + PC) (1: 1 of 65 wt%) system. The solution casting technique is employed throughout the process. The structural, morphology, thermal and ionic conducting behavior of sample are examined. The highest conductivity is 1.2 × 10⁻² S cm⁻¹ at 303 K for P(S-MMA)-PVdF (25:75 of 27 wt%) LiClO₄ (8 wt%)- EC + PC (65 wt%) +6 wt% ZrO₂ system. The linear sweep voltammetry and the cyclic voltammetry tests are performed and the results are discussed. The optimized electrolyte is used to make the LiFePO₄/CGPE/Li confined 2032 coin cell couple. It holds the discharge capacity of 144 mAh g⁻¹ at rate of 0.1 C with 88% coulombic efficiency.     

Effect of plasticizers in poly(vinyl alcohol)‐based hybrid solid polymer electrolytes

Hybrid solid polymer electrolyte films consisting of poly(vinyl alcohol) (PVA), poly(methyl methacrylate) (PMMA), LiBF₄, and ethylene carbonate/propylene carbonate (EC/PC) were prepared with a solvent‐casting technique. The complexation was investigated with Fourier transform infrared and X‐ray diffraction. The ionic conductivities of the electrolyte films were determined with an alternating‐current impedance technique for various temperatures in the range of 302–373 K. The maximum conductivity value, 1.2886 × 10^?3 S/cm, was observed for a PVA–PMMA–LiBF₄–EC complex. Thermogravimetry/differential thermal analysis was performed to ascertain the thermal stability of the electrolyte with the maximum conductivity value. For an examination of the cyclic and reversible performance of the film, a cyclic voltammetry study was carried out. The surface morphology of the EC‐and PC‐based electrolytes was examined with scanning electron microscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2794–2800, 2003