Development of Li(Ni1/3Mn1/3Co1/3-x Na (x) )O-2 cathode materials by synthesizing with glycine nitrate combustion technique for Li-ion rechargeable batteries

Glycine nitrate combustion technique was investigated for synthesizing Li(Ni1/3Mn1/3Co1/3-x Na (x) )O-2, x = 0-0.11 based transition metal oxide cathode materials for the rechargeable Li-ion battery (LIB) under this study. X-ray diffraction and scanning electron microscopy analysis showed that the synthesized powder samples were well crystalline rather spherical secondary particles. These secondary particles were composed of softly agglomerated nano-scale primary particles. The room temperature electrical conductivity of these Na-doped materials was significantly higher than that of the base material (2.60 x 10(-7) S/cm). Among them, the x = 0.04 material reported the highest electrical conductivity of 1.02 x 10(-03) S cm(-1). The half-cell assembled with cathode fabricated from Li(Ni1/3Mn1/3Co1/3)O-2 base material showed an initial discharge capacity of 187 mA h(-1) g(-1) with 25 mA h(-1) g(-1) irreversible capacity loss and 88.47% columbic efficiency at C/5 rate with a cut-off voltage of 2.5-4.6 V at 25 A degrees C. The electrochemical behavior of the x = 0.04 cathode showed a comparable initial discharge capacity as of the base material but with improved capacity retention

Dye sensitized solar cells with poly(acrylonitrile) based plasticized electrolyte containing Mgl(2)

Polymer electrolytes can be used favorably in photo-electrochemical solar cells. A possible electrolyte for this purpose is a polyacrylonitrile-Mgl(2) complex with plasticizers such as ethylene carbonate and propylene carbonate The best ionic conductivity was obtained for samples containing 60 wt% of Mgl(2) salt with respect to the weight of polyacrylonitrile, for example, at 30 degrees C the conductivity is 1.9 x 10(-3) S cm(-1) The ionic contribution to the conductivity is dominant as shown by do polarization tests. Furthermore, the glass transition temperature showed a minimum, -103.0 degrees C. for the sample with the highest conductivity indicating the importance of polymer chain flexibility for the conduction process Measurements on a fabricated solar cell with this electrolyte exhibited an overall energy conversion efficiency of 0.84%. The short circuit current density, open circuit voltage and fill factor of the cell were 2 04 mA cm(-2), 692 mV and 59.3%, respectively

Effect of Nano-Porous Alumina Filler on Thermal and Electrical Transport Properties of Solid Polymer Electrolyte (PEO)12LiBF4

Ionic conductivity, dielectric and thermal properties of (PEO)12LiBF4 solid polymer electrolyte, dispersed with nanoporous Al2O3 have been studied. Out of seven different compositions studied, the (PEO)12LiBF4 polymer-salt complex showed the highest conductivity with σ25 o C = 8.27 × 10-6 S cm-1. Dispersion of different weight ratio of nano-porous alumina fillers to this electrolyte showed that the composite electrolyte composition with 15 wt. % Al2O3 gave the highest conductivity with σ25 o C = 6.05 × 10-5 S cm-1. The glass transition temperature, Tg decreased from -35.3 oC to -43.2 oC and the PEO crystallite melting temperature, Tm decreased from 64.5 oC to 58.8 oC due to the incorporation of 15 wt. % Al2O3 filler, suggesting that the interaction between the PEO backbone and the Al2O3 filler have affected the main chain dynamics of the host polymer. As the presence of the filler results in an increased conductivity mainly due to an increased amount of amorphous phase in the electrolyte above Tm, another mechanism, directly associated with the filler particles, appears to contribute to the observed conductivity enhancement. A possible mechanism for this could be the creation of additional hopping sites and favorable conducting pathways for migrating ionic species though Lewis acid-base type interactions between ionic species and O/OH sites on the filler grain surface. Results of the dielectric relaxation spectroscopy agree with the suggestion that the increased mobility is largely responsible for the obtained conductivity enhancement caused by the nano- porous filler

Effect of Nano-Porous Alumina Filler on Thermal and Electrical Transport Properties of Solid Polymer Electrolyte (PEO)12LiBF4

Ionic conductivity, dielectric and thermal properties of (PEO)12LiBF4 solid polymerelectrolyte, dispersed with nanoporous Al2O3 have been studied. Out of seven differentcompositions studied, the (PEO)12LiBF4 polymer-salt complex showed the highest conductivitywith σ25oC = 8.27 7 10-6 S cm-1. Dispersion of different weight ratio of nano-porous alumina fillersto this electrolyte showed that the composite electrolyte composition with 15 wt. % Al2O3 gave thehighest conductivity with σ25oC = 6.05 7 10-5 S cm-1. The glass transition temperature, Tg decreasedfrom -35.3 oC to -43.2 oC and the PEO crystallite melting temperature, Tm decreased from 64.5 oCto 58.8 oC due to the incorporation of 15 wt. % Al2O3 filler, suggesting that the interaction betweenthe PEO backbone and the Al2O3 filler have affected the main chain dynamics of the host polymer.As the presence of the filler results in an increased conductivity mainly due to an increased amountof amorphous phase in the electrolyte above Tm, another mechanism, directly associated with thefiller particles, appears to contribute to the observed conductivity enhancement. A possiblemechanism for this could be the creation of additional hopping sites and favorable conductingpathways for migrating ionic species though Lewis acid-base type interactions between ionicspecies and O/OH sites on the filler grain surface. Results of the dielectric relaxation spectroscopyagree with the suggestion that the increased mobility is largely responsible for the obtainedconductivity enhancement caused by the nano- porous filler

Effect of plasticizers (EC or PC) on the ionic conductivity and thermal properties of the (PEO)(9)LiTf: Al2O3 nanocomposite polymer electrolyte system

A new plasticized nanocomposite polymer electrolyte based on poly (ethylene oxide) (PEO)-LiTf dispersed with ceramic filler (Al2O3) and plasticized with propylene carbonate (PC), ethylene carbonate (EC), and a mixture of EC and PC (EC+PC) have been studied for their ionic conductivity and thermal properties. The incorporation of plasticizers alone will yield polymer electrolytes with enhanced conductivity but with poor mechanical properties. However, mechanical properties can be improved by incorporating ceramic fillers to the plasticized system. Nanocomposite solid polymer electrolyte films (200-600 mu m) were prepared by common solvent-casting method. In present work, we have shown the ionic conductivity can be substantially enhanced by using the combined effect of the plasticizers as well as the inert filler. It was revealed that the incorporating 15 wt.% Al2O3 filler in to PEO: LiTf polymer electrolyte significantly enhanced the ionic conductivity [sigma(RT) (max)= 7.8 x 10(-6) S cm(-1)]. It was interesting to observe that the addition of PC, EC, and mixture of EC and PC to the PEO: LiTf: 15 wt.% Al2O3 CPE showed further conductivity enhancement. The conductivity enhancement with EC is higher than PC. However, mixture of plasticizer (EC+PC) showed maximum conductivity enhancement in the temperature range interest, giving the value [sigma(RT) (max)= 1.2 x 10(-4) S cm(-1)]. It is suggested that the addition of PC, EC, or a mixture of EC and PC leads to a lowering of glass transition temperature and increasing the amorphous phase of PEO and the fraction of PEO-Li+ complex, corresponding to conductivity enhancement. Al2O3 filler would contribute to conductivity enhancement by transient hydrogen bonding of migrating ionic species with O-OH groups at the filler grain surface. The differential scanning calorimetry thermograms points towards the decrease of T-g, crystallite melting temperature, and melting enthalpy of PEO: LiTf: Al2O3 CPE after introducing plasticizers. The reduction of crystallinity and the increase in the amorphous phase content of the electrolyte, caused by the filler, also contributes to the observed conductivity enhancement

Quasi solid state polymer electrolyte with binary iodide salts for photo-electrochemical solar cells

Quasi-solid-state polymer electrolytes can be used in dye sensitized solar cells (DSSCs) in order to overcome various problems associated with liquid electrolytes. Prior to fabricating commercially viable solar cells, the efficiency of quasi solid state DSSCs needs to be improved. Using electrolytes with a binary iodide mixture is a novel technique used to obtain such efficiency enhancement. In this work we report both conductivity and solar cell performance enhancements due to incorporation of a mixture containing LiI and tetrahexylammonium iodide in a quasi-solid-state electrolyte. The conductivity of the electrolyte increases with added amounts of Lit and thus the highest conductivity, 3.15 x 10(-3) S cm(-2) at 25 degrees C, is obtained for the electrolyte 100 wt% LiI. The predominantly ionic behavior of the electrolytes was established from dc polarization measurements. The iodide ion conductivity, measured using iodine pellet electrodes decreased somewhat with increasing amount of LiI even though the overall conductivity increased. However, the highest efficiency was obtained for the DSSC containing a polymer electrolyte with Hex(4)N(+)I:LiI = 1:2 mass ratio. This cell had the largest short circuit current density of about 13 mA cm(-2) and more than 4% overall energy conversion efficiency. The results thus show that electrolytes with Hex(4)N(+)I/LiI mixed iodide system show better DSSC performance than single iodide systems. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Efficiency enhancement in dye sensitized solar cells based on PAN gel electrolyte with Pr4NI + MgI2 binary iodide salt mixture

The effect of using a binary iodide salt mixture in N719 dye-sensitized TiO2 solar cells (DSSCs) is investigated. The cells use tetrapropylammonium iodide (Pr4NI) and magnesium iodide (MgI2) in a plasticized polyacrylonitrile gel in glass/FTO/nano-porous TiO2/gel, I-2/Pt/FTO/glass solar cell structure. The salt composition in the gel electrolyte is varied to optimize the efficiency of DSSCs. The DSSCs with MgI2 or Pr4NI as the only iodide salt showed the efficiencies 2.56 and 4.16 %, respectively, under AM 1.5 (100 mW cm(-2)) illumination while the DSSC with mixed cations with 18.4:81.6 MgI2:Pr4NI molar ratio shows the highest efficiency of 5.18 %. Thus the efficiency enhancement, relative to the high efficiency end member is about 25 %. DC polarization measurements establish the predominantly ionic behavior of the electrolytes, and show that the variation of efficiency with salt composition correlates with the change in short circuit photocurrent density (J (sc)), which appears to be governed by the iodide ion conductivity. It is also found that J (sc) correlates with the iodide ion transference number estimated from DC polarization data taken with non-blocking iodine electrodes. This study suggests that binary iodide mixtures may be used to obtain efficiency enhancement in different types of DSSCs based on polymeric, gel, or solvent electrolytes