The reports might turn out to be true, as four years ago Samsung SDI, a storage battery manufacturing company, manufactured a curved battery, but of only 210mAh.
As of now, Samsung has been keeping its Galaxy X under covers, but speculating rumors suggest that the phone might finally be available in early 2019, probably the same time as the Samsung Galaxy S10. As per GSM Arena, Galaxy X will reportedly feature 7.3-inch screen when opened, and 4.5-inch when folded.
Also, though nothing is confirmed, but if the phone is actually launched, it will also come in with a hefty price tag. One analyst claimed that it would cost around $1,850