Heavier Thicker Chains and Gears for Winter due to Salt?
Bike chains come in two sizes, 1/8inch (aka BMX chain) and 3/32inch (aka 9 speed chain). 1/8inch chains are designed for single speed or internal hub geared bicycles and the chain is designed in such a way that it can not be derailed from the sprocket. A 3/32inch chain is designed for a derailleur geared bicycle and is designed to ease shifting from one sprocket to another.

The thickness of the chain will have little if anything to do with how the chain behaves or wears due to road salt. People have many different views on how to keep your chain happy and prevent it from wearing, my advice would be to either invest in a full chaincase (for a singlespeed bike) or to dry and lube your chain after it has gotten wet.

The trick to lubing a chain is to use a rag to remove any dirt. Then apply a small amount of a thick bicycle chain oil to the inside side of the chain (the top side of the chain at the bottom side of the bike, or the bottom side of the chain at the top side of the bike, if that makes sense). Finally, spin the chain good and proper to get the lube into the chain (it's useless if it's sitting on the outside of the chain, it needs to work its way inside the links) and then use the rag to remove any excess.

Excess chain oil sitting on the outside of the chain will attract dirt which will cause your chain to wear prematurely.