A highly preferred orientation of I2-LiI(HPN)2 film on the paper was found. The electrochemical property of a new flexible all-solid-state Li/I2-LiI(HPN)2 film paper battery was examined at wide temperatures for the first time. This paper battery is capable of achieving a high discharge energy of 250 Wh/kg with a plateau potential region at 2.70 V versus Li/Li+ at 70 °C. The interfacial layer of (LiI)(1+x)I(2−x) (HPN)2 instead of LiI between lithium and I2-LiI(HPN)2 film should be responsible for the high electrochemical activity of the lithium–iodine paper battery.