Corrosion on my connector?

Hello,

My cable isn't charging as it used to do. When I plug my iPhone 6 in the charger, the iPhone recognises that there is a charger in his port, but it isn't really charging. When I plug my iPhone into my laptop, iTunes pops up just as always and my phone gives the indication of being charged, but still, it isn't charging. The only time my iPhone does charge is when it is plugged into an external battery (portable power bank). When I took a closer look at my lightning connector, there was 1 golden stripe that didn't shine as much as the others... So I was thinking, could this be corrosion or something?
I've checked my iPhone with a family members cable and I know for sure that my phone isn't the problem.