This isn't a solution. You're curing the symptom, not the disease. What you suggest is dangerous, potentially very so. Li-polymer and Li-ion batteries are complex chemical cells. If the voltage is allowed to go too-low, the cells break down and give off hydrogen gas. This is the swelling in the battery. Putting it in the freezer, you're just reducing the volume (and allowing for some adsorption) of the hydrogen. It's still there. If you were to use this battery, the hydrogen can potentially ignite, starting a fire.
Once a battery swells, it needs to be properly disposed. Treat it as an ignition source, and don't let it near flammable items.