Development of an inorganic additive to active materials of lead acid batteries

Summary form only given as follows. The most prominent type of additives that have been used over the years for lead acid batteries are those that impact the functioning of the active materials. Whereas the positive active material (PAM) is usually additive free the negative active material (NAM) is usually modified by a variety of additives, both organic and inorganic. We start off by defining active material additives as those ingredients that are not essential for its functioning, but can improve it The additive can be present in very small amounts, but it can also be present in larger quantities. In this paper we review the functioning of various active material additives and we follow by presenting a family of additives that operate by facilitating electrolyte diffusion to the active materials. These inorganic additives are very inert, being made of chemical resistant boro-silicate glass, and have very defined sizes and geometry. They modify the initial performance and cycle ability of the active materials. The electrical performance profile of the lead acid battery shows that at high rates (short time discharges), the active material efficiency is highly curtailed. It is generally accepted that this is due to the diffusion hindrance of the electrolyte into the active material. This hindrance is reduced when certain amounts of chemical grade glass boro-silicate in the form of glass micro fibers are introduced to battery active materials. The use of these inorganic additives also opens interesting perspectives in the manufacturing process of making the plates of lead acid batteries.