Alvin J. Salkind

Determination of state-of-charge and state-of-health of batteries by fuzzy logic methodology

A practical method of predicting state-of-charge (SOC) and state-of-health (SOH) of battery systems has been developed and tested for several systems. The method involves the use of fuzzy logic mathematics to analyze data obtained by impedance spectroscopy and/or coulomb counting techniques. Fuzzy logic provides a powerful means of modeling complex, non-linear systems without the need for explicit mathematical models. New detailed impedance date has been obtained on the discharge performance of primary lithium/sulfur dioxide cells. Earlier data, obtained by Rutgers co-workers on nickel/metal hydride and other systems, have been reviewed and re-interpreted using fuzzy logic methodology. Devices are being developed for several systems, which will predict the SOC and SOH of batteries without the need to know their previous discharge and/or cycling history.

Nickel hydroxide and other nanophase cathode materials for rechargeable batteries

Abstract The staff of US Nanocorp, Inc. are developing unique nanostructured materials for a wide range of applications in the areas of energy storage (batteries and ultracapacitors) and energy conversion (fuel cells and thermoelectric) devices. Many of the preparations of these materials exploit a wet synthesis process (patent pending) that is scaleable to large volume manufacturing and anticipated to be low in cost. Specifically, both the β -form of nickel hydroxide and the hollandite form of manganese dioxide have been synthesized. The hexagonal Ni(OH) 2 is anticipated to significantly boost energy densities in nickel-alkaline batteries, including nickel/cadmium, nickel/metal hydride and nickel/zinc. The nanophase MnO 2 microstructure exhibits an unusual tunnelled tubular geometry within a ‘birds nest’ superstructure, and is expected to be of interest as an intercalation cathode material in lithium-ion systems as well as a catalyst for fuel cells. Characterization of these materials has been by the techniques of high resolution SEM and TEM, as well as XRD. Both Hg porosimetry and BET surface measurements for conventional and spherical nickel hydroxides are summarized. Pore distribution and electrochemical activity for the nanophase materials will be examined in the future.

Dynamic characterization of small lead-acid cells

Abstract Three sizes of small valve regulated (VRLA) commercially available lead-acid cells were investigated and characterized for their dynamic properties by ac impedance spectroscopy and other electrochemical techniques. All cells were of the limited electrolyte type and no additional electrolyte was introduced during the studies. The data indicates a very significant increase in cell impedance at lower states of charge, as expected. In charging studies close to the fully charged state, some unexpected impedance data were observed. Complex impedance plots indicate a passive film formation, probably associated with the recombination surface film. The investigations included cells in various states of charge as well as cycling history including positional orientation studies. Equivalent circuits were derived from ac impedance spectroscopy and the parameters studied as a function of the cell’s state-of-charge. Furthermore, the voltage response of the cells was theoretically generated from the ac impedance spectroscopy using Fourier transform analysis and found to be similar to the measured cell responses.

Advanced membranes for alkaline primary and rechargeable alkaline cells with zinc anodes

Several advanced cellulosic and radiation grafted polypropylene membrane materials are currently under evaluation in the laboratories at Navsea Crane and Rutgers University, for application to alkaline primary and rechargeable cell chemistries which employ zinc as the anode material. A portion of these tests involve model cell evaluations of cellulosic membranes for silver migration rates through the membranes as a function of separation layers and changes in the degree of polymerisation (DP), wet tensile strength (WTS) and voltage changes at both electrodes as a function of model rechargeable cell life cycle. Other testing on the actual membranes is generating data for both cellulosic and polypropylene materials on impedance, swelling properties, and silver and zinc penetration rates. The overall goal of these investigations is to obtain candidate separation membranes which will reduce zinc anode shape change and shedding and resist alkaline oxidative degradation to extend the active wet life in primary cells and both wet and life cycle in rechargeable cells.

Cellulosic separator applications: new and improved separators for alkaline rechargeable cells

Abstract A study has been established at Naval Surface Warfare Center, Crane Division (NAVSURFWARCENDIV) and Rutgers University to obtain material analysis data on cellulosic separator properties such as tensile strength and swelling of alkaline-soaked film samples, degree of polymerization and crystallinity, cationic and anionic diffusion and penetration rates in alkaline media, and X-ray diffraction for crystallinity. These data are then related to cycleand wet-life information from model electrochemical cells as a function of separator composition on an alkaline chemistry rechargeable cell set. The first examples used in this program are silver-zinc rechargeable cells of 28 Ah capacity, identical in every respect except for the separator composition, which are being tested in statistically significant numbers under identical temperature and relative humidity conditions, with 45% KOH as the electrolyte. The cycle-life test regime of continuous cycling is: C/5 discharge to 1.30 V, and C/30 and C/60 charge to 2.03 V, while the wet-life test regime includes a 30-day wet-stand at full charge between cycles. At the outset of the cell testing, a baseline cell was selected from each set in the matrix after the so-called formation cycling was complete, and the physical properties of crystallinity, tensile strength, and degree of polymerization were re-measured. Then, at intervals during cycleand wetlife cycling, and as cells fail the life tests, these properties will be measured again for selected cells. In this way a correlation will be established between separator life under charge/discharge conditions in actual cells and the critical physical properties of each separator film. Eight separator compositions, all cellulose-based, are being evaluated. The purpose of the study is to utilize the cycle- and wet-life data which are a function of separator composition and physical properties in the alkaline chemistry rechargeable cell set, to designate a ‘best’ separator for incorporation into actual production cells by the manufacturing community for silver/zinc rechargeable cells. The recommendations will take the form of minimum separator physical properties which are beneficial to cell performance and long life, resulting in an improvement in the assets available for Fleet use in the US Navy. This paper discusses the data available to date on cycle- and wet-life, and their relationship to separator physical properties before and at several stages during cycling.

Thermodynamic and Kinetic Study of the Li / MnO2 ⋅ Bi2 O 3 Electrochemical Couple

MnO 2 .(Bi 2 O 3 ) 0.06 cathode material showed improved performance over typical β-MnO 2 in primary lithium battery prototype cells. Studies indicate that Bi 2 O 3 surface-modified β-MnO 2 material provided alternative catalytic discharge mechanisms, which lower the activation energy of the cell reaction.

Intramuscular pH needle microelectrode a preliminary report

THE GLASS ELECTRODE has been historically the means of measuring interstitial pH. Eisenman and his associates [3] have documented it’s performance characteristics. The disadvantages of the glass electrode are its bulk, fragility, and the distance bet,meen the sensing electrode and the reference electrode. More recently, miniature pH electrodes and microelectrodes have become available 11, 2, 4-61 but most of them require special care. The distance between the sensing surface and the reference surface has been reduced in some of these models, but in most, these surfaces are still too widely separated. A new type of electrode utilizing no glass has been developed and is t,he subject of this report. The pH needle electrode (Fig. 1) is of all-metal construction and is contained within an N-gauge hypodermic ncedlc. Although the needle has been made as short as 2 cm, we have chosen 9 cm as a more convenient size. The ele&rode assembly (Fig. 2) consists of a mercury/mercuric oxide (Hg/HgO) or silver/silver chloride (Ag/AgCl) reference surface and an antimony oxide (Sb,O,) pH sensing surface. The needle electrode is a roncent’ric assembly of the pH sensitive film on a stainless steel subsurface and of the reference surface, which is a silver wire conditioned with either mercury or silver

Electrically Driven Implantable Prostheses

The electrochemical and electrical nature of muscular and biological reactions has been known for centuries. The work of Galvani in the eighteenth century in his famous frog leg experiment as a Professor of Anatomy at Padua University, led to Volta’s experiments and epochal discovery of the production of electricity by electrochemical reactions. Galvani also observed what is now known as “injury potential,” the voltage difference between an injured area and the surrounding tissue. The existence of dc or time-varying electrical activity with the majority of physical and chemical processes in living organisms has also been well established. More recently, the electrophysiological aspects of living tissue were investigated by Drs. Yasuda and Fukada.(1)

Key Events in the Evolution of Implantable Pacemaker Batteries

The successful development of implantable cardiac pacemakers has been facilitated by the merging of the relevant technologies in electronics and power sources. The mercury/zinc oxide battery was a key component in the initial development of implantable pulse generators and that battery system is closely associated with the name of Dr. Samuel Ruben (Fig. 1). Subsequently, the lithium/iodine battery was developed for hermetically sealed, longer-lived pulse generators, and this development has been closely associated with the name of Dr. Wilson Greatbatch (Fig. 2). Both of these men are recognized as outstanding inventors and have been creative in a number of technologies.

Oxygen Recombination in Sealed Ni‐Cd Cells with Fiber Substrates

Oxygen recombination in a positive-limited-sealed Ni-Cd cell was investigated. The electrodes were made by electro-chemical impregnation of nickel fiber substrates. The negative electrode capacity was 1.7 times that of the positive electrode capacity, thus preventing hydrogen evolution during overcharge. A model was developed to compute the recombination parameters during charge and overcharge of the positive-electrode-limited sealed Ni-Cd cell. The model was used to study the effect of electrolyte saturation level, initial state of charge of the positive electrodes, and charge rate on recombination kinetics in sealed Ni-Cd cells. A comparison of the recombination rate at rest was made with that during overcharge.