I use this app called bookshelf by Damir Juretic
https://play.google.com/store/apps/details?id=com.bookshelf.prod&pcampaignid=web_share

you can scan the barcodes, or even the ISBN text printed on inner cover.

can have multiple virtual bookshelf's to represent your physical shelfs if you like, has a search feature too.

can export and import csv files of the inventory too

no ads and free, I haven't had any issues with it.