It depends on why you're going to IL. To be deductible the expense has to be ordinary and necessary to that trade or business. If there's a legitimate business reason then maybe, there are still limitations on how long you can live somewhere before it becomes your tax home. You're going to need to elevate this question to a tax attorney so you can go over it in detail.

If you can make an argument to prove its value as a business expense. You should set it up in a way that it can serve as an office. If you manufacture there, conceptualise and design there, or perform any other related aspects of your work there, then it counts as a business expense.

If you're using this apartment as your office space, then yes, normally you can write it off as a business expense. You'll just need to prove it somehow. For example, declaring to the state that the apartment is for commercial use.

I know that where I live, I also need to notify the landlord that I'm doing commercial work in the apartment.

Double-check with state laws though! I am not a lawyer so I cannot give you any legal advice.