How can I store chopped onions in the fridge without the smell?
I regularly store chopped onion in my refrigerator (or at least halves &amp; quarters). 

I either use tight-sealing plastic containers or zip-top bags. You may want to double-bag in zip-tops to be sure to avoid a smell. 

One problem you may be having is onion-ness getting on the outside of the container. Be sure the outside is all clean and dry - no point in having a nicely sealed packet of onion when the outside can get all stinky anyway.