Brian Gaff brought next idea :
I have noticed recently that battery connectors in portable gear seem poorly
made with no plating and also often dissimilar metals of the spring and the
rivet and the tag where the wire goes often making the connection crackly, if
for example inside a microphone.

Almost all the battery terminals and springs I come across these days,
even in the cheapest gear, are formed from stainless. Any damage from
battery leaks, can be just brushed away with a toothbrush.