I wonder if you have ever dismantled a ordinary Laptop battery...
Yes indeed, several of them.
...and replaced the cells?
No. After researching the subject online
, and after seeing the cost of equivelant quality replacement cells plus the work required to solder them in, considered against the cost of discounted OEM replacements, I decided it wasn't worth it.
For my ThinkPads I use only Lenovo OEM batteries, I don't trust many of the lower cost (and quality) replacements due to potential fire and explosion hazards as well as hit-or-miss performance. I've been buying genuine Lenovo batteries at discounted prices from ServerSupply.com
for several years now and have never been dissapointed.