Studies of Time-Potential Changes on an Electrode Surface during Current Interruption

Abstract

A d‐c current interrupter method has been developed for oscilloscopic studies of time‐potential changes at an electrode surface during short interruption intervals. A variable length square pulse with a very short rise time and with a duty factor of approximately one per cent was used to interrupt the current flow in a cell. Studies were conducted using interruption times from one microsecond to 120 microseconds.This interrupter technique permitted correction for the resistance error in closed circuit potential measurements. Polarization decay and build‐up could be followed as the current was cut off and turned on, and the potential changes and double layer capacity effects occurring at an electrode surface during interruption could be measured. These phenomena have been discussed in terms of an equivalent electrical circuit. An initial study of polarization phenomena on the zinc anode‐steel cathode system in a synthetic sea water electrolyte was carried out using this interrupter method.

Lithium/iron sulfide batteries for electric-vehicle propulsion and other applications. Progress report, October 1979-September 1980

“…Recent advances in making MgO powder resulted in a form of powder having a very large surface area (>70 m /g) with fine particle size, which results in a low bulk density when the powder is packed as a separator. A bulk density of 0.40 g/cm 3 with a porosity of 88% can be achieved with this new form of powder.…”

“…This potential shift is usually attributed to the IR drop associated with the ohmic resistance across the prevailing current path in the system being investigated. 3 , 4 This explanation is probably valid for cells containing small nonporous electrodes with uniform current density, 5 but is inadequate for large porous electrodes because nonuniform current and potential distributions can develop across the electrode structures during charge and discharge (see ANL-79-94, p. 115).…”

“…where K is a temperature-dependent constant that was previously determined calorimetrically 2 and evaluated thermodynamically. 3 3 , 3 4 The positive sign is for discharge and the negative for charge. The analyses presented above were tested by estimating the heat generation as a function of time for a 6-V module containing five Mark IA cells and then comparing these values with three temperature measurements made inside the module during its 50th discharge.…”

Polarization Studies of the Lead-Acid Storage Cell

“…Similar curves hIve been obtained frequently for single electrodes. 6,7,8 It has been attempted to represent the equivalent electricaL circuit of the battery at each electrode in the way shown in where A and B are capacitance-resistance combinations corresponding to the Helmholz layer (or diffuse double layer) and to concentration polarization, respectively. R, is the solution resistance between the electrodes.…”

On Dissolved Oxygen in Bulk Platinum

“…Finally the steady-state, hydrogen-overvoltage curve was determined for stepwise increasing and decreasing current density on the front side of the foil with purified H2, N2, or O2 bubbling in the back-side compartment. Note that H2 is always bubbled in the front-side compartmenL A constant current interrupter (25,26) was used to correct for the solution iR and to monitor the cleanliness of the system by observing the pseudocapacitance of the H2 reaction on the Pt foil (27). It was necessary to determine the iR correction for each reading because gas bubbles forming over the Pt surface caused large variations in the value of the solution iR, chiefly in the high current density region.…”