MEASUREMENT OF TRUE SURFACE AREA IN ELECTRODES.
Abstract
Double-layer capacitance measurements were selected as a means to measure true surface areas. When a constant-current pulse is applied to the double layer capacitance inside a pore, the change of voltage is usually observed to be nonlinear with time. This report provides experimental verification of theoretical predictions by others on how such a voltage transient is related to the geometric dimensions of the pore, the electrolyte resistivity, and the double-layer capacitance. New theoretical work shows a capacitance charging curve will become linear with time (a) for a single uniform pore, (b) for multiple pores of uniform shape, with or without mixed dimensions, and (c) for finite multiple pres with any shape. Faradaic current is shown to have negligible effect if that reaction current is constant and small relative to the capacitance charging current. Measurements on porous carbon and sintered nickel plaques give areas from 20 to 80% of BET values. Thus, a substantial part of the surface of these electrodes appears to be unwetted. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1966
- Accession Number
- AD0632729
Entities
People
- J. Mccallum
- R. F. Redmond
- R. W. Hardy
Organizations
- Battelle Memorial Institute