Michel Saakes

Investigations of the negative plate of lead/acid cells 1. Selection of additives

Abstract A procedure is proposed for the selection of inhibitors and expanders used as additives for the negative plate of the lead/acid battery. Inhibitors were selected by performing d.c. and a.c. measurements at pure metals (Cu, Sb, Ag), which are assumed to act as local active sites for the hydrogen-evolution reaction at the negative plate. From this study anisaldehyde was found to show strong preferential adsorption at Cu and Sb. Expanders were selected using a.c. impedance measurements at a Pb electrode at a low anodic discharge current. Selected expanders were Indulin C and Na-1-naphtol-4-sulfonate. From the impedance measurements information was obtained not only on the expander action but also on the effect of the additive on the double layer and the diffusion properties of lead sulfate. From a study on the concentration dependence of the expander (Na-1-naphtol-4-sulfonate) an optimal effect was found at a concentration of about 600 ppm.

Advanced bipolar lead–acid battery for hybrid electric vehicles

Abstract A large size 80xa0V bipolar lead acid battery was constructed and tested successfully with a drive cycle especially developed for a HEV. The bipolar battery was made using the bipolar plate developed at TNO and an optimised paste developed by Centurion. An empirical model was derived for calculating the Ragone plot from the results from a small size 12xa0V bipolar lead–acid battery. This resulted in a specific power of 340xa0W/kg for the 80xa0V module. The Ragone plot was calculated at t =5 and t =10xa0s after the discharge started for current densities varying from 0.02 to 1.2xa0A/cm 2 . A further development of the bipolar lead–acid battery will result in a specific power of 500xa0W/kg or more. From the economic analysis we estimate that the price of this high power battery will be in the order of 500 US

Development and testing of a bipolar lead-acid battery for hybrid electric vehicles

/kWh. This price is substantially lower than for comparable high power battery systems. This makes it an acceptable candidate future for HEV.

Investigations of the negative plate of lead/acid cells 2. Verification with 2 V cells

An 80 V bipolar lead-acid battery was constructed and tested using hybrid electric vehicle (HEV) drive cycles. Drive cycles with a peak power of 6.7 kW, equal to 1/5 of the total power profile required for the HEV studied, were run successfully. Model calculations showed that the 80 V module constructed, which is at the moment 2.5 times heavier than required for the HEV operation studied, can be optimised to meet the requirements.

Performance and use of composite-substrate-based bipolar lead/acid batteries for pulsed-power applications

Abstract Tests in 2 V cells were performed to study the cause of the decrease of capacity and cell voltage. It was found that the capacity of aged cells increased significantly when expanders like Indulin C and Na-1-naphthol-4-sulfonate were added. The cell voltage, lowered by an excess of hydrogen evolution, increased after addition of anisaldehyde. The beneficial effect of both the expanders and inhibitor lasted for several tens of cycles. Addition of anisaldehyde in an aged 2 V submarine cell (8.9 kAh), at a temperature of 30 °C, gave an increase of cell voltage of 145 mV. This increase is almost entirely due to an increase in overvoltage of the hydrogen-evolution reaction at the negative plate. Measurements in 2 V cells confirm the results of short time tests on smooth lead electrodes described in part 1.

Investigations of the negative plate of lead/acid cells 3. Model calculations of the impedance of self-similar porous electrodes

Abstract A new type of composite substrate is proposed for constructing fast discharge bipolar lead/acid batteries.This newly developed substrate, used for constructing 4 V bipolar lead/acid batteries, displays no corrosion and a very low catalytic effectfor both hydrogen and oxygen evolution. The specific resistance is 1.2 Ω cm while the areal resistance is 0.04 Ω cm 2 . The activelayers are formed by the Plante formation method, both in situ and ex situ. For pulsed-power applications, where energy is quickly transferredto an inductor, a model calculation is given for deriving the required ratio of the specific power and the specific energy.

Rechargeable lithium battery

In this paper a model for the calculation of the admittance (reciprocal impedance) of a porous metal electrode is derived, under anodic constant-current conditions, during precipitation of an insoluble salt at the metal/electrolyte interface. An example of the discharge, at low current density, of the negative plate in a lead/sulphuric acid battery during which lead sulphate is formed. The discussion is based on the assumption that porosity has a self-similar fractal character. The impedance of fractal electrodes will be discussed in terms of geometrical and physical parameters.