The external surface area of carbon additives as key to enhance the dynamic charge acceptance of lead-carbon electrodes

• Published in: Journal of energy storage Vol. 15; pp. 196 - 204
• Main Authors: Settelein, J., Oehm, J., Bozkaya, B., Leicht, H., Wiener, M., Reichenauer, G., Sextl, G.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2018
• Subjects: Carbon additives; Double-layer capacity; Dynamic charge acceptance; External surface area; Hydrogen evolution; Lead-acid batteries; Lead-acid batteries; Dynamic charge acceptance; External surface area; Carbon additives; Hydrogen evolution; Double-layer capacity
• ISSN: 2352-152X; 2352-1538
• DOI: 10.1016/j.est.2017.11.016

•Synthesized hard carbons with specific external surface area varied over one decade.•The external surface area triggers chemisorption processes on the carbon surface.•Correlation to the electrochemical activity of lead-carbon electrodes are found.•Hydrogen evolution reaction and double-layer capacity are influenced directly.•The carbon external surface area correlates to the dynamic charge acceptance (DCA). The dynamic charge acceptance (DCA) of modern lead-carbon batteries is one of the key parameters for their future application in micro- and mild-hybrid cars. This work elucidates the impact of the external surface area of carbon additives on the electrochemical performance of lead-carbon electrodes with respect to the DCA. Five specially synthesized amorphous hard carbon powders with different specific external surface area ranging from 13m2g−1 to 192m2g−1 were added to the negative active material of laboratory lead-carbon test cells. Results from cyclic voltammetry reveal that the specific external surface area of amorphous carbons exhibits a clear correlation to the electrochemical activity of lead-carbon electrodes. Firstly, an almost linear increase of the activity of the hydrogen evolution reaction with increasing specific external surface area of the carbon additive can be found. Secondly, the specific double-layer capacity of the negative active material is directly linked to the specific external surface area of the additive, as well. Thirdly, a clear correlation to the DCA can be established. In conclusion, a high specific external carbon surface in the negative active material seems to be a key to improve the dynamic charge acceptance of modern lead-carbon batteries.