Impedance parameters and the state-of charge. I. Nickel-cadmium battery

The problem of nondestructive determination of the state-of-charge of nickel-cadmium batteries has been examined experimentally as well as theoretically from the viewpoint of internal impedance. It is shown that the modulus of the impedance is mainly controlled by diffusion at all states of charge. Even so, a prediction of the state of charge is possible if the equivalent series/parallel capacitance or the alternating current phase shift is measured at a sufficiently low a.c. test frequency (5–30 Hz) which also avoids inductive effects. These results are explained on the basis of a uniform transmission-line analog equivalent circuit for the battery electrodes.

Synthesis and electrical properties of the (PVA)(0.7)(Kl)(0.3)center dot xH(2)SO(4) (0 <= x <= 5) polymer electrolytes and their performance in a primary Zn/MnO2 battery

Solid acid polymer electrolytes (SAPE) were synthesised using polyvinyl alcohol, potassium iodide and sulphuric acid in different molar ratios by solution cast technique. The temperature dependent nature of electrical conductivity and the impedance of the polymer electrolytes were determined along with the associated activation energy. The electrical conductivity at room temperature was found to be strongly depended on the amorphous nature of the polymers and H2SO4 concentration. The ac (100 Hz to 10 MHz) and dc conductivities of the polymer electrolytes with different H2SO4 concentrations were analyzed. A maximum dc conductivity of 1.05 x 10(-3) S cm(-1) has been achieved at ambient temperature for electrolytes containing 5 M H2SO4. The frequency and temperature dependent dielectric and electrical modulus properties of the SAPE were studied. The charge transport in the present polymer electrolyte was obtained using Wagner's polarization technique, which demonstrated the charge transport to be mainly due to ions. Using these solid acid polymer electrolytes novel Zn/SAPE/MnO2 solid state batteries were fabricated and their discharge capacity was calculated. An open circuit voltage of 1.758V was obtained for 5 M H2SO4 based Zn/SAPE/MnO2 battery. (C) 2010 Elsevier Ltd. All rights reserved.

Missile battery placement for air defense: A dynamic programming approach

A procedure to evaluate surface-to-air missile battery placement patterns for air defense is presented. A measure of defense effectiveness is defined as a function of kill probability of the defense missiles and the nature of the surrounding terrain features. The concept of cumulative danger index is used to select the best path for a penetrating hostile aircraft for any given pattern of placement. The aircraft is assumed to be intelligent and well-informed. The path is generated using a dynamic programming methodology. The software package so developed can be used off-line to choose the best among a number of possible battery placement patterns.

A crosslinked ``polymer-gel'' rechargeable lithium-ion battery electrolyte from free radical polymerization using nonionic plastic crystalline electrolyte medium

A cross-linked polymer-gel soft matter electrolyte with superior electrochemical, thermal and mechanical properties obtained from free radical polymerization of vinyl monomers in a semi-solid organic nonionic plastic crystalline electrolyte for application in rechargeable lithium-ion batteries is discussed here.

Ionic conductivity, mechanical strength and Li-ion battery performance of mono-functional and bi-functional (''Janus'') ``soggy sand'' electrolytes

Influence of dispersion of uniformly sized mono-functional and bi-functional (''Janus'') particles on ionic conductivity of novel ``soggy sand'' electrolytes and its implications on mechanical strength and lithium-ion battery performance are discussed here.

Sputter deposited LiPON thin films from powder target as electrolyte for thin film battery applications

Lithium phosphorus oxynitride (LiPON) thin films as solid electrolytes were prepared by reactive radio frequency (rf) magnetron sputtering from Li3PO4 powder compact target. High deposition rates and ease of manufacturing powder target compared with conventional ceramic Li3PO4 targets offer flexibility in handling and reduce the cost associated. Rf power density varied from 1.7 Wcm(-2) to 3 Wcm(-2) and N-2 flow from 10 to 30 sccm for a fixed substrate to target distance of 4 cm for best ionic conductivity. The surface chemical analysis done by X-ray photoelectron spectroscopy showed incorporation of nitrogen into the film as both triply, NE and doubly. Nd coordinated form. With increased presence of NE, ionic conductivity of LiPON was found to be increasing. The electrochemical impedance spectroscopy of LiPON films confirmed an ionic conductivity of 1.1 x 10(-6) Scm(-1) for optimum rf power and N-2 flow conditions. (C) 2011 Elsevier B.V. All rights reserved.

Thermal sensitivity analysis of spacecraft battery

Transient thermal sensitivity is studied for systems that are subjected to conductive heat transfer within themselves and radiative heat transfer with the surrounding environment, including solar heat radiation, The battery in the Indian national communication satellite is one such system for which the studies are conducted with respect to panel conduction, conductance of insulating blanket, power dissipation within the battery, and absorptance and emittance of various elements, Comparison of sensitivities revealed that battery temperature is sensitive to its power dissipation during the beginning of life of the spacecraft, whereas toward the end of life of the spacecraft mission, the effect of absorptance of optical solar reflector is dominating, The influence of optical property values of the multilayer insulation blanket is almost negligible. Among the parameters studied in this analysis, the battery temperature is found to be mast sensitive to emittance of the optical solar reflector.

Performance and scaling of a 1.2 V/1.5 Ah nickel/metal hydride cell to a 6 V/1.5 Ah battery

A 1.2 V/1.5 Ah positive-limited nickel/metal hydride cell has been studied to determine its charge-discharge characteristics at different rates in conjunction with its AC impedance data. The faradaic efficiency of the cell is found to be maximum at similar to 70% charge input. The cell has been scaled to a 6 V/1.5 Ah battery. The cycle-life data on the battery suggest that it can sustain a prolonged charge-discharge schedule with little deterioration in its performance.

A portable battery-operated chip thermocycler based on induction heating

A microchip thermocycler, fabricated from silicon and Pyrex #7740 glass, is described. Usual resistive heating has been replaced by induction heating, leading to much simpler fabrication steps. Heating and cooling rates of 6.5 and 4.2 degreesC/s, respectively have been achieved, by optimising the heater dimensions and heating frequency (similar to200 kHz). Four devices are mounted on a heater, resulting in low power consumption (similar to 1.4 W per device on the average). Using simple on-off electronic temperature control, a temperature stability within -0.2 degreesC is achieved. Features such as induction heating, good temperature control, battery operation, and low power consumption make the device suitable for portable applications, particularly in polymerase chain reaction (PCR) systems. (C) 2002 Elsevier Science B.V. All rights reserved.

One step synthesis of monoclinic VO2 (B) bundles of nanorods: Cathode for Li ion battery

One of the metastable phases of vanadium dioxide, VO2(B) bundles of nanorods and microspheres have been synthesized through a simple hydrothermal method by dispersing V2O5 in aqueous quinol. The obtained products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and electrochemical discharge-charge test for lithium battery. It was found that the morphologies of the obtained VO2(B) can be tuned by manipulating the relative amount of quinol. The electrochemical test found that the bundles of nanorods exhibit an initial discharge capacity of 171 mAh g(-1) and its almost stabilized capacity was reached to 108 mAh g(-1) after 47 cycles at a current density of 0.1 mA g(-1). The formation mechanism of the VO2(B) bundles of nanorods and microspheres was also discussed. (C) 2012 Elsevier Inc. All rights reserved.

Sonochemical Synthesis of Pt Ion Substituted TiO2 (Ti0.9Pt0.1O2): A High Capacity Anode Material for Lithium Battery

Doping of TiO2 with a suitable metal ion where dopant redox potential couples with that of titanium (Ti4+) and act as catalyst for additional reduction of Ti4+ to Ti2+ (Ti4+ -> Ti3+ -> Ti2+) is envisaged here to enhance lithium storage even higher than one Li/TiO2. Accordingly, 10 atom% Pt ion substituted TiO2, Ti0.9Pt0.1O2 nanocrystallites was synthesized by sonochemical method using diethylenetriamine (DETA) as complexing agent. Powder X-ray diffraction pattern (XRD), Rietveld refinement and TEM study reveals that Ti0.9Pt0.1O2 nanocrystallites of similar to 4 nm size crystallize in anatase structure. X-ray photo-electron spectroscopy (XPS) study confirms that and both Ti and Pt are in 4+ oxidation state. Due to Pt4+ ion substitution in TiO2, reducibility of TiO2 was enhanced and Ti4+ was reduced up to Ti2+ state via coupling of Pt states (Pt4+/Pt2+/Pt-0) with Ti states (Ti4+/Ti3+/Ti2+). Galvanostatic cycling of Ti0.9Pt0.1O2 against lithium showed very high capacity of 430 mAhg(-1) or exchange of similar to 1.5Li/Ti0.9Pt0.1O2. (C) 2012 The Electrochemical Society. DOI: 10.1149/2.029208jes] All rights reserved.

Benefits of Electronic Wiring and Spacers on Lithium Storage in Nanostructured Lithium-Ion Battery Anodes

The demand for high power density lithium-ion batteries (LIBs) for diverse applications ranging from mobile electronics to electric vehicles have resulted in an upsurge in the development of nanostructured electrode materials worldwide. Graphite has been the anode of choice in commercial LiBs. Due to several detrimental electrochemical and environmental issues, efforts are now on to develop alternative non-carbonaceous anodes which are safe, nontoxic and cost effective and at the same time exhibit high lithium storage capacity and rate capability. Titania (TiO2) and tin (Sn) based systems have gained much attention as alternative anode materials. Nanostructuring of TiO2 and SnO2 have resulted in enhancement of structural stability and electrochemical performances. Additionally, electronic wiring of mesoporous materials using carbon also effectively enhanced electronic conductivity of mesoporous electrode materials. We discuss in this article the beneficial influence of structural spacers and electronic wiring in anatase titania (TiO2) and tin dioxide (SnO2).

PEO|Sncl(2)|PANI composites: as an electrolyte in solid-state battery

Solid-state polymer electrolytes possess high conductivity and have advantages compared with their liquid counterparts. The polyethylene oxide (PEO)-based polymer is a good candidate for this purpose. The PEO/SnCl2/polyaniline composite (PSP composites) at different weight percentages were prepared in anhydrous acetonitrile media. Structural studies were carried out of the prepared composites by X-ray diffraction, Fourier transmission infrared spectroscopy, and surface morphology by scanning electron microscopy. The sigma (dc) was carried out by a two-probe method, and it is found that the conductivity increases with an increase in temperature. The temperature-dependent conductivity of the composites exhibits a typical semi-conducting behavior and hence can be explained by the 1D variable range hopping model proposed by Mott. The electrochemical cell parameters for battery applications at room temperature have also been determined. The samples are fabricated for battery application in the configuration of Na: (PSP): (I-2 + C + sample), and their experimental data are measured using Wagner's polarization technique. The cell parameters result in an open-circuit voltage of 0.83 V and a short-circuit current of 912 mu A for PSP (70:30:10) composite. Hence, these composites can be used in polymer electrolyte studies.

A soluble-lead redox flow battery with corrugated graphite sheet and reticulated vitreous carbon as positive and negative current collectors

A soluble-lead redox flow battery with corrugated-graphite sheet and reticulated-vitreous carbon as positive and negative current collectors is assembled and performance tested. In the cell, electrolyte comprising of 1 center dot 5 M lead (II) methanesulfonate and 0 center dot 9 M methanesulfonic acid with sodium salt of lignosulfonic acid as additive is circulated through the reaction chamber at a flow rate of 50 ml min (-aEuro parts per thousand 1). During the charge cycle, pure lead (Pb) and lead dioxide (PbO2) from the soluble lead (II) species are electrodeposited onto the surface of the negative and positive current collectors, respectively. Both the electrodeposited materials are characterized by XRD, XPS and SEM. Phase purity of synthesized lead (II) methanesulfonate is unequivocally established by single crystal X-ray diffraction followed by profile refinements using high resolution powder data. During the discharge cycle, electrodeposited Pb and PbO2 are dissolved back into the electrolyte. Since lead ions are produced during oxidation and reduction at the negative and positive plates, respectively there is no risk of crossover during discharge cycle, preventing the possibility of lowering the overall efficiency of the cell. As the cell employs a common electrolyte, the need of employing a membrane is averted. It has been possible to achieve a capacity value of 114 mAh g (-aEuro parts per thousand 1) at a load current-density of 20 mA cm (-aEuro parts per thousand 2) with the cell at a faradaic efficiency of 95%. The cell is tested for 200 cycles with little loss in its capacity and efficiency.