The 4046 is Phase Lock Loop chip, but is not suitable for what you want to do. It's Voltage Controlled oscillator will only operate to ~2MHz or less, and put out a tiny signal (compared to what you need).
For experimental use, you should be looking for a surplus Radio Frequency Signal Generator capable of producing 1 to 10MHz sine wave output. Most such oscillators put out ~1V to 5V into a 50Ohm load, so you will have to follow it up with an RF Power Amplifier capable of putting out several Watts to hundreds of Watts into a low impedance load. ( A huge, expensive amplifier)
This would enable you to do some basic testing to see if you can find some frequency that actually does something at some magic resonance frequency.
I remain a huge skeptic! I am convinced that breaking up sulphate crystals in lead-acid batteries can be done just fine by using a simple DC constant-current "equalization charge".