Expander Mix for Standard and New Battery Applications
In recent years, lead–acid batteries have experienced a strong evolution that has been driven by micro-hybrid (for start–stop) and mild-hybrid electric vehicles, in which both energy recovering and boosting on acceleration is provided by the battery. To fulfil the tasks required by these systems, it is necessary to develop lead–acid batteries with enhanced electrical characteristics. For example, (i) improved cranking ability is required to accommodate the strong increase in the number of cranking operations during vehicle life; (ii) greater charge-acceptance to recover as much as possible of the braking energy to lower both fuel consumption and carbon dioxide emissions. Furthermore, as the battery operates at an almost constant partial state-of-charge, it is necessary to counteract the deleterious effect of the heavy sulfation that develops especially in the negative plates and thereby limits the life of the battery. During the last decade, numerous studies have demonstrated the outstanding characteristics of organic expanders and carbon materials to control the heavy sulfation of negative plates. This presentation will analyse the key properties of these organic expanders and their roles together with those of several carbon and graphite types in terms of battery performance.
Melchor Fernández began his career as a Chemical Engineer in the Research & Development Center at Exide Technologies. His career has focused on the development of VRLA Technology for automotive, standby, motive power and cycling batteries. More recently, he has addressed the development of both the enhance-flooded battery for start–stop and the spiral-wound VRLA batteries for mild-hybrid vehicles. Melchor now works as a consultant.