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Simplified Mathematical Model for Effects of Freezing on the Low-Temperature Performance of the Lead-Acid Battery
No full textDischarge periods of lead-acid batteries are significantly reduced at subzero centigrade temperatures. The reduction is more than
what can be expected due to decreased rates of various processes caused by a lowering of temperature and occurs despite the fact
that active materials are available for discharge. It is proposed that the major cause for this is the freezing of the electrolyte. The
concentration of acid decreases during battery discharge with a consequent increase in the freezing temperature. A battery freezes
when the discharge temperature falls below the freezing temperature. A mathematical model is developed for conditions where
charge-transfer reaction is the rate-limiting step, and Tafel kinetics are applicable. It is argued that freezing begins from the
midplanes of electrodes and proceeds toward the reservoir in-between. Ionic conduction stops when one of the electrodes freezes
fully and the time taken to reach that point, namely the discharge period, is calculated. The predictions of the model compare well
to observations made at low current density C/5 and at −20 and −40°C. At higher current densities, however, diffusional
resistances become important and a more complicated moving boundary problem needs to be solved to predict the discharge
periods
Recovery and reuse of Ni(II) from rinse water of electroplating industries
No full textDischarge of nickel compounds, which may occur in both liquid and solid phases, can cause severe environmental
problems. In this work, ‘point of source’ treatment strategy is followed and reduced the nickel
content of rinsewater to about less than 1mg L−1 by ion-exchangemethod using a packed column involving
batch recirculation mode of operation and to recovered Ni(II) content by desorption. The treatedwater
could be recycled for rinsing operation.
The nickel from resin is first precipitated as nickel hydroxide to synthesize positive active material and
that was used in Nickel/Metal hydride cell. The performances in terms of electrochemical utilization of
nickel hydroxide, specific capacity as a function of discharge current density and cycle lifewere examined
and the nickel hydroxide electrode with 5% CaCO3 addition, having 200mAhg−1 specific capacity, could
be subjected to charge/discharge cycles at C/5 rate for more than 200 cycles without the capacity fadin
Chitin-Incorporated Poly(ethylene oxide)-Based Nanocomposite Electrolytes for Lithium Batteries
No full textNanocomposite polymer electrolytes (NCPE), with different proportions of poly(ethylene oxide)/LiClO4/
chitin were prepared by a hot press method. Nanochitin, a biopolymer, poly(�-(1f4)-N acetyl-D-glucosamine)
was incorporated as a filler in poly(ethylene oxide) (PEO). The ionic conductivity of the composite polymer
electrolytes was enhanced by one order upon addition of nanochitin. The lithium transference number, tLi
+, was increased from 0.24 to 0.51 upon chitin addition. The membranes were subjected to scanning electron
microscopy, thermogravimetric-differential thermal analysis, differential scanning calorimetry, ionic
conductivity, and Fourier transform infrared (FTIR) spectroscopy analysis. The free volume Vf was probed
by positron annihilation lifetime spectroscopy studies at 30 °C. Li/NCPE/Li symmetric cells were assembled,
and the thickness of the solid electrolyte interface as a function of time was analyzed. This paper also describes
FTIR spectroscopic studies of the interface between lithium metal and NCPE, which suggests that the surface
chemistry of lithium electrodes in contact with NCPE is dominated by compounds with C-N-Li and C-O-Li
bonding
Influences of different TiO2 morphologies and solvents on the photovoltaic performance of dye-sensitized solar cells
No full textThe effects of TiO2 photoelectrode’s surface morphology and different solvents on the photovoltaic performance
of dye-sensitized solar cells (DSSCs) were studied. By successive coating of TiO2 suspension,
composed of low and high molecular weight poly(ethylene)glycol (PEG) as a binder, double layered TiO2
photoelectrodes with four different structures were obtained. Among the DSSCs with different TiO2
electrodes, DSSC with P2P1 electrode (P2 and P1 correspond to PEG molecular weights of 20,000 and
200,000, respectively) showed higher performance under identical film thickness at a constant irradiation
of 100mWcm−2, whichmay be correlated with large pore size and high surface area of the corresponding
TiO2 electrode. Thiswas confirmed by electrochemical impedance spectroscopy (EIS) analysis of the DSSC
and the transient photovoltage measurement of electrons in the TiO2 electrode. Among the different solvents
investigated here, the DSSC containing acetonitrile showed high conversion efficiency and the order
of performance of the DSSCs with different solvents were AN>MPN> PC > GBL >DMA>DMF> DMSO.
Better correlationwas observed between the donor number of solvents and photoelectrochemical parameters
of the DSSCs containing different solvents rather than the measured viscosity and dielectric constant
of solvents. The reasons for the low performance of the DSSCs containing DMA, DMSO and DMF, respectively,
were due to the negative shift of TiO2 conduction band and the desorption of dye molecules from
the TiO2 photoelectrode by those solvents
Cerium and zinc: Dual-doped LiMn2O4 spinels as cathode material for use in lithium rechargeable batteries
No full textPristine spinel lithiummanganese oxide (LiMn2O4) and zinc- and cerium-doped lithiummanganese oxide
[LiZnxCeyMn2−x−yO4 (x = 0.01–0.10; y = 0.10–0.01)] are synthesized for the first time via the sol–gel route
using p-amino benzoic acid as a chelating agent to obtain micron-sized particles and enhanced electrochemical
performance. The sol–gel route offers shorter heating time, better homogeneity and control over
stoichiometry. The resulting spinel product is characterized through various methods such as thermogravimetic
and differential thermal analysis (TG/DTA), Fourier-transform infrared spectroscopy (FT-IR),
X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX)
and electrochemical galvanostatic cycling studies. Charge–discharge studies of LiMn2O4 samples heated
at 850 ◦C exhibit a discharge capacity of 122mAhg−1 and a corresponding 99% coulombic efficiency in
the 1st cycle. The discharge capacity and cycling performance of LiZn0.01Ce0.01Mn1.98O4 is found to be
superior (124mAhg−1), with a low capacity fade (0.1mAhg−1 cycle−1) over the investigated 10 cycles
Lithiated assemblies of metal chalcogenide nanowires
No full textWe study hexagonal assemblies of M6X6 M=Mo and W and X=S, Se, and Te nanowires from
first-principles calculations to understand their structural stability, electronic properties, and the
effects of Li intercalation. It is shown that due to van der Waals interactions between the nanowires,
the intercalation is achieved without a significant change in their atomic structure. With an increase
in Li concentration, we predict a new phase for Li3Mo6S6 compound, in which the hexagonal
assembly transforms to a monoclinic structure by a change in the orientation of nanowires. The
LixMo6S6 assemblies are electrically conductive and can be potentially used as cathode materials in
Li-ion batteries for nanoscale applications. The voltage of such a battery, calculated to be 1.7 V,
can be manipulated such as by iodine doping without a significant change in the atomic structure
Synthesis of NASICONsA Molecular Precursor-Based Approach
No full textPhosphosilicate molecular precursor for the synthesis of NASICON, natrium super ionic conductor,
Na1+xZr2SixP3-xO12 (x ) 1 and 2) has been devised and prepared by the hydrolysis of tetraethoxysilane
(TEOS) employing sodium phosphate solution. The molecular precursor was reacted with Zr(OC3H7)4 in
ethanol under solvolytic condition to yield nano precursor material of NASICON. This material was
annealed at high temperature to yield phase-pure NASICON. The molecular precursor was characterized
using 31P NMR, FTIR spectral data, powder XRD pattern and TG/DTA studies. The structure of the
molecular precursor was deduced from the powder XRD data, which indicates the presence of edge
sharing tetrahedral arrangement of -O-Si-O-P-O-Si- chain. The NASICON precursor material
was characterized using TG/DTA, FTIR, TEM, SEM, MAS 31P NMR and XRD. The conductivity of the
synthesized NASICON material was measured using the pellet annealed at 900 °C and was found to be
5.5 x10-3 S cm-1. The details on the preliminary investigation are presented in this paper
Development of Novel Acidizing Inhibitors for Carbon Steel Corrosion in 15% Boiling Hydrochloric Acid
No full textThe inhibiUve action oj l-cinnamyLidine-3-thiocarbohydrazide (eTCH) and 1.1'-dicinnamyLidine-3-thiocarbohydrazide (DCTCH) against Lhe corrosion ojcarbon steel in 15% hydrochLoric
acid (HCL) was investigated u.sing noneLectrochemicaL and eLectrochemicaL techniques. Potentiodynamic polarization studies revealed that the compounds were mixed-type inhibitors
and exhibited more than 97% inhibition efficiency at
1.500 ppm oj inhibitor concentration. The effect of temperature on l/ lC corrosion behavior ojcarbon steel in 15% HCl with
1.500 ppm Ql'inhibitors was studied in the temperature range
Jrom 30°C to 11 a°c. The sLLrfac coverage (8) increased linearLy
witlt the Loqaritltm of the inhibitor concentrationjitting a Temkin adsorption isotherm. Thermodynamic parameters including
theJree energy ojadsorption, activation energy. enthalpy.
entropy. and heat ojudsoTption were also calcLLlated. The inhibitors reduced the hydrogen permeation current effectively
through the st eL sttrface. The protective}ilmJormed on the metaL surface by the adsorption ojorganic compounds was confirmed using Fourier trans/om1injrared (FTIR). ttltravioLet
(UV}-visibLe reflectancc. and scanning eLectron microscopy
(SEM) studirs
Combustion synthesized LiMnSnO4 cathode for lithium batteries
No full textNovel category LiMnSnO4 compound was synthesized via. Urea assisted combustion (UAC) method at 800 �C and examined for possible
use as cathode material in lithium-ion batteries. The XRD (X-ray diffraction) results of LiMnSnO4 sample authenticate the orthorhombic
crystal structure with high degree of crystallinity. Presence of uniformly distributed nanometric grains (scanning electron
microscopy) with preferred local cation environment is evident from FT IR (Fourier transform infra red spectroscopic) and 7Li
NMR (nuclear magnetic resonance spectroscopy) studies. The charge–discharge behavior of Li/LiMnSnO4 cells demonstrated a specific
capacity of 113 mA h/g, with an excellent capacity retention (95%) and Ah efficiency (>99%). Besides, the internal resistance of the Li/
LiMnSnO4 cell after 30 cycles is negligibly small, thus demonstrating good electronic conductivity and cycling stability, required for any
lithium intercalating cathode material
Total dissolved solids removal by electrochemical ion exchange (EIX) process
No full textIn the present investigation, synthetic wastewater was prepared by the addition of required amount of
salts into deionized water. Their performance, on removal of Cl−, SO42−, PO43−, Ca2+, Fe2+ and Mg2+ in
laboratory scale plate and frame type electrochemical ion exchange (EIX) cells, were evaluated under
varying operating conditions. Ruthenium dioxide coated titanium plates (RuO2/Ti) were used as anode
and stainless steel plates as cathode in all the four different EIX cells used in the present investigation. All
the four EIX cells were run for a maximum of 7 h. Almost complete removal of all the above ionic solids
were observed within 4.5–7 h under one or more test conditions