The / is only required for XHTML & XML.
If you're using a HTML5 doctype, then there's no need to terminate self-closing tags in this way.
This applies to <img src="img.png" />, <br />, <hr /> etc.
I.e. Just use <img src="img.png">, <br> and <hr>.
If you need an empty element (like a div), don't use <div />, instead use <div></div>. This is important since in HTML5, the slash is ignored and <div /> is interpreted as <div> without a closing tag.