ALL Lithium ion batteries, which is used in most, if not all, modern laptops are better used plugged in than otherwise.
even while it's plugged in, the battery life will still slowly die out, though it's not as bad as constantly charging and discharging the battery which whittles away the battery more rapidly.
personal tip; only run on it's battery when there's no power socket nearby, like in a plane. additionally, and apparently this seems to work based on some accounts from other users here, if you want to preserve your battery life as much as you can, get a zip lock bag, put the battery in it making sure there's no moisture in it, and put it in the fridge, i troll you not. it doesn't preserve much, but you do see a bit of an improvement, apparently.