dell xps 9550 battery swelling up when getting warm

Actually, Dell lately does have instructions for handling swollen batteries. 

https://www.dell.com/support/article/us/en/19/sln128667/dell-laptop-battery-frequently-asked-questions?lang=en

https://www.dell.com/support/manuals/us/en/19/precision-15-5530-laptop/swollenbattery/handling-swollen-lithium-ion-batteries?guid=guid-6a7dc90d-fb31-42cd-a503-41597c89f321&lang=en-us

Most of the info is okay, except for a few bits: 

> ... While a swollen pack does not represent a safety concern ...

While it is true that most swollen batteries don't tend to blow up and potentially start a fire, now and then some of them does, and there have been a few reports involving Dell laptop batteries. So they must be treated as an increased fire risk.  

> we recommend discontinuing use and replacing it with a Dell authorized battery 

This is a very good recommendation, except that it often appears to be difficult to get one from Dell. I wouldn't recomment buying a "genuine", "original" etc from any other source than Dell service (because they don't seem to sell them elsewhere) - if you can't get a new one (not "refurbished"!?) straight from Dell, better try to find a "compatible" one from a reputable battery brand, but mind you likely won't be able to send it back if it does't work. 

> ... Lithium-ion polymer batteries have increased in popularity in recent years and have become standard in the electronics industry due to customer preferences for a slim form factor (especially with newer ultra-thin laptops) and long battery life. Inherent to lithium-ion polymer battery technology is the potential for swelling of the battery cells...

But there surely are engineering means of detecting swelling early and disconnecting the battery automatically, at reasonable costs.