Kathryn R. Bullock

Batteries, 1977 to 2002

Battery systems have undergone significant improvements over the past 25 years. Older systems have been updated with new materials and constructions. New lithium and nickel systems have been introduced, especially in the rechargeable segment, and have undergone tremendous growth and reached maturity. The technology and applications of the various battery systems are reviewed here, and the status of commercial aqueous and nonaqueous systems updated. NEC first introduced electrochemical capacitors in August 1978 under the trade name Supercapacitor. Electrochemical capacitor technology has evolved from first generation products with low energy density for memory protection applications through several generations of designs to create megajoule-size capacitors for transportation and power quality applications.

The Effect of Phosphoric Acid on the Positive Electrode in the Lead‐Acid Battery II . Constant Potential Corrosion Studies

The effect of on the constant potential corrosion of the positive grid in the lead‐acid battery has been studied. The metallurgical and chemical properties of the corrosion products have been examined and correlated with their electrochemical behavior during self‐discharge and voltammetric cycling. Low concentrations of in the electrolyte modify the crystal growth of on the lead grid, producing a structure which is not readily discharged to .

The Effect of Phosphoric Acid on the Positive Electrode in the Lead Acid Battery

The effect of phosphoric acid on the positive electrode reaction in a lead--acid battery is studied by cyclic voltammetry. It is proposed that phosphate reversibly adsorbs on the PbO/sub 2/ during charge and modifies the crystal growth of PbO/sub 2/ on the lead grid. The form of PbO/sub 2/ produced in the presence of phosphate is not easily reduced to lead sulfate and, therefore, the positive grid does not become insulated from the active material. The limit of this effect is reached at a low concentration of phosphoric acid. 6 figures.

Electrochemical and spectroscopic methods of characterizing lead corrosion films

Abstract One of the major causes of failure in lead-acid batteries is the corrosion of the lead current collector at the lead dioxide electrode. The corrosion films which form are complex because changing voltage and concentration gradients across the film favor different reaction products as corrosion progresses. Although excellent studies have been accomplished using mainly electrochemical techniques, X-ray diffraction, electron microscopy, and metallography, development of additional knowledge has been frustrated by the following limitations of these methods: (1) poor resolution of the signals from the many lead compounds which form in the corrosion film, (2) poor spatial resolution of the multiple corrosion product layers which are evident in micrographs of film cross sections, and (3) the inability to analyze the corrosion products in situ to determine the time sequence of species formation. Recently several new approaches to studying lead corrosion films have overcome some of these limitations. These techniques, which include laser Raman spectroscopy, photocurrent and photoacoustic spectroscopy and solid state electrochemistry, are reviewed. Significant results from their application are summarized.

Self‐Discharge in Acid‐Starved Lead‐Acid Batteries

A lead-acid battery stored in an acid-starved condition, rather than in a totally flooded state, shows a well-behaved and predictable decline in open-circuit voltage with time. The voltage-time curves of such batteries can be used to determine the rates of the predominant self-discharge reactions and to study the reaction mechanisms. An abrupt change in the slope of the curve indicates a change in the dominant self-discharge process. Acid-starved automotive (SLI) batteries with antimonial-lead grids show a slope change at 1.85 V/cell. This apparently corresponds to a change in the grid corrosion mechanism. Measurements of gas evolution from these SLI batteries show that the rate of hydrogen evolution is dependent on the acid concentration whereas the rate of evolution of carbon dioxide is independent of acid concentration. Oxygen reacts rapidly at the negative plate. 26 refs.

The electromotive force of the leadacid cell and its half-cell potentials

Abstract The literature values of the activity coefficients of sulfuric acid, and the activities of water as a function of the molality of aqueous sulfuric acid and temperature, are reviewed and evaluated. Approaches to fitting these values to a suitable equation are also reviewed. A self-consistent set of values for acid and water activities and the standard potentials of the leadacid cell and mercurous sulfatemercury electrode are identified. These values are used to calculate the electromotive force (e.m.f.) of the leadacid cell from 0.1 to 30 m H 2 SO 4 . Temperature coefficients for the e.m.f. are also available from 0 to 60 °C. Accurate half-cell potentials versus a mercurous sulfatemercury electrode can be calculated for molalities from 0.1 to 7.2 and for temperatures from 0 to 55 °C.

Effect of antimony on lead-acid battery negative

The role of antimony on the lead-acid battery negative in terms of its effect on charge efficiency, its effect on gassing overpotential, its interactive influence with lignin expander in controlling the charge efficiency, and its retentive behavior or purging characteristics as SbH/sub 3/ in the overcharge gas stream was investigated. Linear potential sweep (LPS) cycling of Plante-type lead electrodes were used to determine the effect of antimony on gassing overpotential and to monitor its concentration either in the active material or the exit gas stream. Results showed a significant contribution of antimony in decreasing charge efficiency and an overwhelming role of lignin expander in suppressing the effect of antimony on charge efficiency. The critical lead-electrode potential for purging antimony from the electrode is close to -1275 mV (vs. Hg/Hg/sub 2/SO/sub 4/).

A Conductive Additive to Enhance Formation of a Lead/Acid Battery

This paper reports on barium metaplumbate, a conductive ceramic having the perovskite structure, which is relatively stable in sulfuric acid. Addition of this material in positive plates in a lead/acid battery significantly improves formation efficiency. The formation mechanism is changed when the conductive particles are dispersed in the plate. Formation not only proceeds from the grid toward the center of the pellet but also slowly around the conductive particles in the plate. The conductive paths of PbO{sub 2} grow and make connection with each other during formation to establish a network which further facilitates the formation.

The Kinetics of the Self‐Discharge Reaction in a Sealed Lead‐Acid Cell

The kinetics and mechanism of the self-discharge reaction in a sealed, lead--acid cell were investigated. The unique cell design and the purity of the materials used produce a slower rate of self-discharge and a different mechanism than the traditional lead--acid battery. Particular attention is given to the effects of expander composition and phosphoric acid concentration on the reaction. Rates of the reaction are determined for temperatures in the range of 35 to 65/sup 0/C.

Rechargeable Zn-MnO2 alkaline batteries

In this paper progress in the development of rechargeable alkaline zinc-manganese dioxide cells is described. The advantages and limitations of the system are evaluated. Laboratory tests run on commercial primary alkaline cells as well as model simulations of a bipolar MnO{sub 2} electrode show that the rechargeable alkaline battery may be able to compete with lead-acid, nickel-cadmium, and secondary lithium cells for low- to moderate-rate applications. However, because of this poor performance at high rates and low temperatures, the alkaline MnO{sub 2} battery is not suitable for present automotive starting applications.