The cells in any laptop battery can be replaced, but there is electronics inside and you need to be able to solder. The cases are usually sonically welded, too, so once you get it open you'll be on your own to devise a way to get it to stay together again. The cells that OEM's use in their batteries are usually the cheapest ones available. If you spend a little more for high capacity cells, you'll get a lot longer life out of your battery packs.