Yurly, Thank you for contacting us. Those blades will not fit. These will https://www.homedepot.com/p/RYOBI-RM480e-Electric-Riding-Mower-Combo-Blade-Accessory-ACRM002/301004222
Are the mulching blades the same as the combo blades? I don't know which mine came with. I'm guessing the bagging blades since it came with a bagging system (which I don't use).
The blades move a lot more air which means more work is being performed which requires more energy so the batteries will not last as long - but probably not a lot less.