Not going to work and probably not safe. The nominal voltages of different battery chemistries are often different and you can’t use lithium ion chargers interchangeably with lead acid chargers. They make LFP batteries that are backwards compatible but those aren’t used in laptops.

Fair chance old laptop batteries are going to be well and truely past their serviceable life.

Lead acid batteries are highly recyclable, and more easily recycled than lithium ion cells anyway.

By old I mean used not old-by-age. I usually buy a new laptop every 3 years

Have you looked in to what’s required to balance-charge the cells?

I’ve seen some blog and YouTube videos where people have repurposed 18650 lithium ion cells.

There’s a bit to it, but it’s doable.