Grab a text on RF filtering. An ARRL handbook is a good place to start. Pure capacitance isn't going to work, as w8ye said a battery is already a pretty good capacitor. Not many people are going to hand you a circuit they've spent hours perfecting in order to sell. If it was easy it would have been done years ago. You're also going to need a pretty good scope to troubleshoot with. Have fun with it.
John