Launcher icons
48 × 48 (mdpi)
72 × 72 (hdpi)
96 × 96 (xhdpi)
144 × 144 (xxhdpi)
192 × 192 (xxxhdpi)
512 × 512 (Google Play store)
source: http://iconhandbook.co.uk/reference/chart/android/
using ionic tool
ionic resources android --icon --force