Conductive Lubricant for Connectors?

In marine applications silicone grease is used on all copper contacts for corrosion resistance: water-resistant, non-corrosive, etc.

The lubricant does not need to be conductive - the contact pressure between connector halves will push the lubricant out of the way and ensure a good connection. A wide range of lubricants will work for your application. Try dielectric grease (sold for starter battery terminals), petroleum jelly, or WD-40 (wiped, not sprayed). As long as it is very liberally applied and doesn't chemically attack/soften the plastic shell of the connector, it will likely work just fine.

Be sure to mechanically strain relieve the assembly so that the connector housings take the load during disconnect rather than the conductors. If you had a bad crimp on the battery side of the connector, you might pull the connector right off the battery leads during the disconnect event, allowing them to short together directly. Not recommended!

If you really insist on something that

• is a lubricant and
• is somehow conductive

graphite powder comes to my mind.

It is commonly used as lubricant for locks.
I don't know, however, if it is a good idea to use it for connectors.

Here graphite is recommended also for electrical connectors.