Abstract
Organic expanders represent essential additives to the negative active material of lead/acid batteries, since they prevent the negative electrode from compaction during life cycling. Focussing on stability and efficiency of expanders, industrial lignosulfonates and humic substances from peat bogs, in comparison, were fractionated, chemically altered and analysed. With respect to a correlation of functional groups and expander action, these organic samples, fractions, and derivatives were assessed based on a cyclovoltammetric determination of expander performance. The majority of the humic material showed poorer aptitude than the commercially available lignosulfonate expanders. Improved performance was found for precursors of humic acids with a low molecular weight. The obtained results indicate the bonding mechanisms by functional groups like cation exchange, chelating, or formation of π-ϵ complexes do not seem to be significant. A good expander aptitude of some humic derivatives is attributed to their colloidal nature. It is assumed that the coagulation of colloids with low molecular weight is hindered, as these colloids form adsorbed surface films in the negative active material. The films cause an overpotential for the reduction of PbSO 4 resulting in fine-grained structures of the lead particles.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
