There's no note about incompatibility other than having to remove the 2.5" SATA drive if it's present, so there's a high probability the 6-cell will simply drop in and work.  
I need to buy a new battery for my Inspiron 7590.  When I go to the PC Accessories on Dell, I have options to buy either a 3-cell or a 6-cell battery.   Questions: (1) will both of these work on my computer?  (2) What are the differences - e.g., is battery life longer with the 6-cell?  (3) Will the 6-cell block a slot or have some other unintended consequence?  Thanks in advance!
Inspiron 7590 Battery - Will both 3 and 6 cell work?