I ordered 4 pc Kaidomain NCR18650GA 3500mAh unprotected button top batteries to be used with Q8. I am very disappointed because at the button tops ventilation holes there seems to be sharp little bit raised edges that will scrape against the brass ring. Very disappointing!
I agree that it would be better if those edges were not there, but it will still take you a couple of decennia to wear that brass ring through 
Or else, sand or file it flat (from the underside to prevent filings to fall into the venting holes).
I sanded down the sharp edges as advised. I can now see some cobber color there, also on top of the buttons as I also sanded down there a bit. Is this no problem even though the BTs outer metallic layer has been some sanded away?
I did not know that BTs had a metal layer covering the inner core of brass / cobber, what is the reason for that? I do not think Samsung 30Q has this kind of BT?
I think it is a nickel coating and the core is iron. You can coat iron with nickel directly, there is always a thin copper layer in between.
And I’m sure that it is no problem that some nickel is sanded away.