The addition of carbon materials to the negative electrode of a lead‒acid battery can significantly improve both its performance and cycle-life at high charging currents. Whereas there is a general agreement on the overall benefit of the carbon additive, the mechanism of its action has yet to be determined. Consequently, the key properties of carbon that cause the performance improvements have not been clearly identified.
This presentation describes a new hybrid carbon additive, TIMREX® CyPbrid™, which is designed especially for advanced lead‒acid batteries in both industrial and automotive applications. Its performance in the negative electrode is compared with that given by crystalline graphite, expanded graphite, carbon black, and mixtures thereof. Carbon hydrophilicity, tap density and oil absorption are key properties for assisting the incorporation and dispersion of carbon in the negative paste. TIMREX® CyPbrid™ combines these properties and therefore is easily incorporated. The carbon affinity to lead and the electrical resistivity are identified as important determinants of the performance of carbon additives in the negative plate. Spontaneous formation of lead nucleation seeds is observed on selected carbon materials when exposed to a lead-rich environment. The seeds facilitate plating of the lead during battery charge when carbon is present in a negative plate. Electrical resistivity influences the final negative electrode resistivity. The selection of the right carbon additive is a compromise of these properties and the final electrode and battery requirements.
Imerys Graphite & Carbon Switzerland Ltd.
R&D Application Development Scientist
Biography: Dario Cericola holds a Doctor of Science qualification. He received his Bachelor of Science in Materials Chemistry in 2005 and his Master of Science in Photochemistry and Materials Chemistry at the University of Bologna, Italy. In 2011 he received a PhD from the Chemical Engineering department of the Eidgenössische Technische Hochschule (ETH) Zürich (Switzerland) in the field of Electrochemistry applied to lithium-ion batteries and electrochemical capacitors. Since August 2011 Dario has been Application Scientist in the Research & Development Laboratory of IMERYS Graphite and Carbon (former TIMCAL Graphite and Carbon) dealing with various battery systems. He is involved in several projects and leading the functional carbon for LAB project.