I'm recently assigned a project to make a battery charger, using logic gates. But I have no idea how to proceed. I'm in need of guidance. I have basic knowledge but not so deep. So I think I can design it, but I just need a push-up.
I'm recently assigned a project to make a battery charger, using logic gates
Sounds like a mission impossible to me, you simply can't make a Li-Ion battery charger using only logic gates. You can't. period.
To properly and safely charge a Li-Ion battery you need to have a well defined voltage reference available. This is needed to make sure that charging stops when the battery voltage is around 4.1 to 4.3 V.
With only logic gates available there is no way to create or detect such a voltage accurately enough.
Whoever gave you that assignment is either joking or doesn't have a clue.