Make it fair for your dog
You need to make crate training fair for your dog. Some owners only crate their dog once in a while, but for many hours. This is not fair to the dog. In order to have your dog accept the crate as a safe and secure resting place, you need to give him the time he needs to get used to it. If you plan to crate your dog, introduce this concept early on to him (ideally when he is a small puppy). If you stick a 4 year old dog that has never been crated before in a kennel for 5 hours, chances are this might actually cause some aggression!
The Bottom Line
Crate training done right will not cause aggression. However, if you do not follow basic guidelines, your dog may develop boundary frustration. If kids, other dogs or other pets of the household can walk by the dog and taunt him, he is likely to start lashing out at everything in front of his crate. Don’t make the mistake to create such boundary aggression.

Instead make the crate a place of comfort and relaxation. Allow your dog plenty of time to get used to it and provide soft bedding so that he feels comfortable.
If your dog already is aggressive, crating alone will not change this. The best way to address aggression is to work with a qualified and experienced in-person trainer.