Help finding a Dell OEM battery compatible for an Inspiron 15 5559

I need help finding out which Dell batteries are compatible with an Inspiron 5559. I lent it to someone, and they left it go years without use, so the battery's no good now. Still works perfectly fine when plugged in, but I'd like for it to have its portability back.

It came with an M5Y1K Dell battery. But it looks like Dell doesn't sell those anymore. And searching for compatible power parts for this laptop just gives a bunch of cables - no batteries. I tried searching the batteries part number to see if search would give equivalents, and the first two results, WYT3M and 6C0FN, seem promising, especially the former: the underside is very similar to the M5Y1K, but its outside design is different.

The product descriptions weren't helpful in determining compatibility. The specs are bare-bone and the low-quality pictures don't even let me see the voltage or eyeball the dimensions. But from cross-referencing their compatible laptops, it looks like the WYT3M outputs 11.1V, and the 6C0FN outputs 7.40V. The Inspiron 5559 is specified to use 14.8 VDC...So, I suppose it won't work out?

Anyway for Dell to let me purchase a compatible battery for this laptop? If all else fails, I managed to find this from BatteriesPlus. Would you recommend using that?