Hi everyone! So I have 5V 2A receiver and transmitter coils but my robot consumes 4A and 12 Volt. Also I am looking for a fast charging solution.How can I do that?
You can't.
You are completely restricted by the "SIZE" and efficiency of the Antennas.
What You are asking for is a 60+VA "Air-Core"-Transformer, built in 2 separate halfs.
There are very good reasons why these are not manufactured.
It would be massive, and completely impractical.