Is there a PCB coplanar edge connector made for high power transmission instead of data transmission?
It is not unusual to use edge connectors to distribute high current. For example there are a few plug-in server power supplies used on HP server that do just that. The DPS-800 PS can kick out over 80A on an edge connector, but the trick they use is that the current is distributed over a large number of contacts. See this article for an insight. 

There are also some connectors that can offer up to 40A per contact such as the Molex Bus Bar Socket, Extreme PowerEdge, or the Hirose PS4 series, which can deliver up to 300A per contact