Britannica Sources used in this answer

How is antimony used in automobile storage batteries?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A labeled periodic table entry for antimony shows its symbol Sb, atomic number 51, atomic weight 121.76, electron configuration, and name. It is a solid, weakly acidic other metal with a rhombohedral crystal structure at room temperature. — antimony Properties of antimony.

Antimony is primarily used in automobile storage batteries as an alloying agent for lead, creating a material known as antimonial lead or hard lead.12

In lead-acid storage batteries, this alloy is used to cast the grids and terminals. The addition of antimony is essential because it imparts necessary strength and hardness to the lead, which would otherwise be too soft for these structural components.23

While traditional antimonial lead alloys typically contain between 1 and 8 percent antimony, "maintenance-free" automotive batteries often utilize lower concentrations, such as 1.5 to 3 percent in negative plates. Additionally, the performance of these lead-antimony grids can be further improved by the inclusion of small amounts of silver. Because of its role in providing this structural integrity, antimony is also frequently reclaimed from the scrap lead of old batteries.243