Budget: Under 100 USD.
Requirement: I want to charge my laptop twice.
Powerbanks are almost universally specified with Ah at 3.7V, so equivalently your laptop is the same as a 11350mAh @ 3.7V powerbank. To charge it twice, you'd need at least 22700mAh, plus around 10% to account for the loss during the charging process. So around 25000mAh is required.
Currently my battery lasts for 4-5 hrs but it'll degrade in the future, so I am asking for being able to charge twice.