SECONDARY BATTERIES – LEAD– ACID SYSTEMS | Lead Alloys

Abstract

Lead is alloyed with various elements to provide mechanical strength and creep resistance to battery parts such as grids, internal connectors between cells, posts, bushings, and external connectors. Lead combined with antimony has been the predominant alloy for use in lead–acid batteries for many years. Lead–antimony alloys have a low melting point, are easily cast into the required shapes, and have high mechanical properties to permit easy processing into finished batteries. The antimony also modifies the surface of the positive grid to permit excellent recharge of the battery after discharge. Antimony, however, is transferred to the negative plate during use, where it accelerates the consumption of water in the battery. Lead–calcium and lead–calcium–tin alloys have been developed to reduce water consumption and are used for maintenance-free batteries. Batteries produced from grids and connectors of nonantimonal alloys have rapidly replaced lead–antimony alloys for use in automobile starting, standby power, and more recently labeled valve-regulated lead–acid batteries. These alloys are weaker and more creep-prone than lead–antimony alloys, but can be produced at high rates on automated grid manufacturing equipment with better tolerance than conventional permanent mold cast lead–antimony alloys. Newer alloys of lead–tin and lead–calcium–tin–silver have been developed to reduce corrosion, improve recharge, and increase battery life in batteries exposed to elevated temperatures and isolated environments. This article is designed to assist the reader to understand the various lead–acid battery components and the lead alloys utilized to produce the batteries.