All batteries can "potentially" swell and explode but the risk is pretty low with modern and reputable products. "No true scotsman" of "modern and reputable" aside, I don't think it's something to worry about.

I and an acquaintance got identical Onn i3/4gb laptops (clearanced for 100usd). They left theirs plugged in constantly while I used the mechanism above. Three months later, theirs was suffering from spicy pillow, bad enough to rip the screw holders for the case, while mine is ok so far. I think the mechanism above is reasonable for shady hardware like the Onn laptop but I hope your Lenovo might do better.

If fits plugged in and running 24/7 and is old enough most laptops can run without a battery.