In the documentation for batik, it shows how to get an instance of the DOM implementation from the class org.apache.batik.dom.svg.SVGDOMImplementation.
I had the same issue with Apache Batik 1.8. The official binaries of that version are not compatible. To get the version 1.8 work I had to replace fop-transcoder-allinone-1.1.jar by fop-transcoder-allinone-2.2.jar which I took from Apache Batik 1.9.