One thing that I like about Fujifilm cameras is they have a tendency to use similar batteries across different camera models.
Take for example the NP-W126 battery.
The NP-W126 is used in the X-Pro1, X-E1, X-E2, X-M1, X-A1 and the X-T1, and a whole lot of other cameras.
Same thing with the x100 battery NP-95 used in the X100s and 100 and even the older f31d compact cameras.
No amount of battery innovation can double the amount of capacity in a short period of time as compared to two batteries. Just look at the Micro Four Thirds camera where the battery models are changing so often and their capacity improvement are often not that significant. By not significant, I mean doubling of capacity. Worse, many of the camera companies introduce technology that lock out third party batteries, not so for Fujifilm.
It's great that Fujifilm reuse the same battery models across different cameras.