The best information I can find on this battery is that it complies with all of the SMBus v1.1 standards. According to the SMBus v1.1 manual, the bus is "designed to operate over a range of voltages between 3 and 5 Volts +/- 10%." That makes me think the Uno's I2C Bus should be ok, no?
The battery is fully charged (according to the little LCD display on top of it).
I have not tested the Uno with any other I2C devices, unfortunately. I may be able to drum something up just to test it. I'll get back to you on that.