N. Munichandraiah

A Review of state-of-charge indication of batteries by means of a.c. impedance measurements

A non-destructive estimation of the state-of-charge (SoC) of batteries facilitates optimum utilization of the battery for a given application, as well as evaluation of its state-of-health. Among various methods, a.c. impedance spectroscopy over a wide range of frequencies provides a variety of parameters which are functions of the SoC of a given battery. These parameters and their variation with SoC depend on the type of battery and on the experimental conditions. The impedance data of sealed commercial cells are rather tedious to analyze since the results are generally the combined parameters of both the positive and the negative electrodes. Separation of the parameters which correspond to the individual electrodes involves assumptions, the validity of which is open to question. Nevertheless, systematic linear and reproducible variations of measurable or computable impedance parameters with battery condition are useful indicators of the SoC in a non-destructive way. The present review consolidates the literature on the prediction of the SoC of batteries by means of a.c. impedance measurements.

Stabilized α ‐ Ni ( OH ) 2 as Electrode Material for Alkaline Secondary Cells

Hydrotalcite-like compounds of formula Ni1-xAl(x)(OH)2(CO3)x/2 . nH2O (x = 0.1 to 0.25), having the same structure as that of alpha-Ni(OH)2, have been synthesized by substituting nickel hydroxide with aluminum. Of these, the compounds of compositions x greater-than-or-equal-to 0.2 are found to have prolonged stability in strong alkaline medium. The electrodes comprising stabilized alpha-Ni(OH)2 of x = 0.2 composition are rechargeable with discharge-capacity values of 240 (+/- 15) mAh-g-1 and are attractive for applications in various alkaline secondary cells employing nickel-positive electrodes.

High Capacitance of Electrodeposited MnO2 by the Effect of a Surface-Active Agent

Manganese dioxide has been electrochemically deposited on a Ni substrate from a neutral electrolyte in the presence of a surface-active agent, namely, sodium lauryl sulfate ~SLS!, for supercapacitor application. The potentiodynamically prepared oxide provides higher capacitance than the potentiostatically and galvanostatically prepared oxides. Owing to adsorption of the surfactant molecules at the interface during electrodeposition, the manganese dioxide possesses higher specific surface area. Specific capacitance of 310 F g−1 obtained for the oxide prepared in the presence of SLS over an extended charge-discharge cycling is higher by about 25% in relation to the oxide prepared in the absence of SLS.

Synthesis and Characterization of Nano- MnO2 for Electrochemical Supercapacitor Studies

Nanostructured MnO 2 was synthesized at ambient condition by reduction of potassium permanganate with aniline. Powder X-ray diffraction, thermal analysis (thermogravimetric and differential thermal analysis), Brunauer-Emmett-Teller surface area, and infrared spectroscopy studies were carried out for physical and chemical characterization. The as-prepared MnO 2 was amorphous and contained particles of 5-10 nm diameter. Upon annealing at temperatures >400°C, the amorphous MnO 2 attained crystalline α-phase with a concomitant change in morphology. A gradual conversion of nanoparticles to nanorods is evident from scanning electron microscopy and transmission electron microscopy (TEM) studies. High-resolution TEM images suggested that nanoparticles and nanorods grow in different crystallographic planes. Capacitance behavior was studied by cyclic voltammetry and galvanostatic charge-discharge cycling in a potential range from -0.2 to 1.0 V vs SCE in 0.1 M sodium sulfate solution. Specific capacitance of about 250 F g -1 was obtained at a current density of 0.5 mA cm -2 (0.8 A g -1 ).

Electrochemical Supercapacitor Studies of Nanostructured α-MnO2 Synthesized by Microemulsion Method and the Effect of Annealing

Nanometer-scale particles of

Fabrication and evaluation of 450 F electrochemical redox supercapacitors using inexpensive and high-performance, polyaniline coated, stainless-steel electrodes

MnO_2

Electrooxidation of methanol on Pt-modified conductive polymer PEDOT.

have been synthesized by microemulsion route for electrochemical supercapacitor studies. The

A cyclic voltammetric study of the kinetics and mechanism of electrodeposition of manganese dioxide

MnO_2

Synthesis and Characterization of Carbon-Coated LiNi1/3Co1/3Mn1/3O2 in a Single Step by an Inverse Microemulsion Route

has been found to be in \alpha-cyrstallographic form with tetragonal unit cell. Particles in the spherical/hexagonal shape with about 50 nm size have been observed in scanning electron microscopy and transmission electron microscopy studies. Cyclic voltammograms have exhibited rectangular shape between 0 and 1.0 V vs saturated calomel electrode at sweep rates up to

Surface films of lithium: an overview of electrochemical studies

100 mV s^{-1}