HTML

Ion-img in center of screen

<div class="vertical-center">
  <div class="center">
    <ion-img src="imgename" class="ion-align-self-end"></ion-img>
  </div>   
</div>

add this in css file
.vertical-center{
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
}