Britannica Sources used in this answer

Why is arsenic added to lead alloys used in batteries and cable sheathing?

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

A labeled diagram of the periodic table entry for arsenic, showing its atomic number 33, symbol As, atomic weight 74.921595, electron configuration, and classification as an other nonmetal. Additional icons indicate arsenic is solid at room temperature, has a rhombohedral crystal structure, and weakly acidic oxides. — arsenic Properties of arsenic.

Arsenic is added to lead alloys used in batteries and cable sheathing primarily to improve their mechanical properties. Because pure lead is relatively soft and has poor mechanical strength, the addition of small concentrations of arsenic serves to harden the metal, making it more durable for these industrial applications.12

In the context of lead-acid storage batteries, arsenic is often included alongside other alloying elements like antimony, tin, copper, and silver to enhance the performance and structural integrity of the cast metal grids and terminals. Similarly, in cable sheathing, the inclusion of arsenic helps provide the necessary hardness and strength required for the material to maintain its shape and protect the internal components of the cable.32