No! You cannot use it!

z550 works with BST-33 (i believe) whici is a good battery if used on the j300 :D (up to 10 days) However, z550 needs more energy so that small battery will keep the phone alive a few days, depending on what you do. The only battery that is compatible with is BST-36(7) which comes with k750/w800... battery that is far better but... thiker. Thee phone will work with it but you won`t be able to close the case.

W300 works with another type of battery (i do not know the name as my phone is being serviced) wich is larger so it won`t fit!

I am sorry to say but you are stuck with a good battery, but good only for small phones :)

Happy buying!!!!