Battery (All): Terminology: Corrosion
WARNING: This page is about a different car, the 2010 Volvo V70, 2009 Volvo V70, and 2008 Volvo V70. However, it is still accessible from the selected car via links, so may be relevant.
A destructive chemical reaction when metal is broken down in an aggressive chemical environment. Sulfuric acid, for example, is aggressive against iron. The iron breaks down and corrodes. The battery terminal is vulnerable to corrosion if it is not maintained correctly.