Increment o clear bagde

Implement push notifications with firebase for Ionic. I send the notifications from an api made in node like this:

var payload = {
                                notification: {
                                    title: "Ejemplo",
                                    body: "!Hola!!!",
                                    sound: 'default',
                                    badge: '1'

What I would like to do is increase the bagde of notifications when they have not been opened yet, using: setBadgeNumber(badgeNumber) , But I do not know in which event I can do this, I handle the notifications with onNotificationOpen, but this is launched only when the application is opened and not when it is in the background … any ideas?