It wouldn’t be my first choice with smartthings. ( I told you I was now using aqara cameras which is a whole different situation.)
Read the FAQ, you will find lots of discussion there. In particular, follow the link to cheap contact sensors and you should be able to find some for under $15 US that will work well. 
Needing cheap contact sensor (2020)
I forgot to mention that pretty much any Zigbee or Z wave sensor should have decent battery life. Zigbee will probably be a little bit better, but not really noticeably so in this kind of device.