An integrated battery system, which integrates solar power and rechargeable battery in the same unit, is an effective solution for the shortage and inefficiency of power energy. We initially present an integrated photo-assistant rechargeable lithium-iodine (Li-I₂) battery system by using hybrid iodine@activated carbon/N719-dye/titanium dioxide (I₂@AC/N719-dye/TiO₂) composite as dual functional photoelectrode. In this integrated battery system, the photovoltage generated on the hybrid photoelectrode compensates the charging voltage of the cell, which decreases the charging potential by ~ 100 mV under chronoamperometry test. Exactly, under illuminated condition, the integrated Li-I₂ battery extending the charge/discharge capacity from 171/166 mAh g^-1 to 204/193 mAh g^-1, respectively, with a higher energy efficiency of 93 % (output electric energy/input electric energy) than that of Li-I₂ battery (that is ~ 87 %). Furthermore, the accelerated redox kinetics of lithium polyiodine conversion are also revealed by the enhanced electrochemical behavior and density functional theory calculation. We believe that such design with the integrated photo-assistant rechargeable Li-I₂ battery can hew out a new way to realize the application of efficient solar energy conversion and storage.
 

hybrid iodine photoelectrode, photo-assisted, lithium-iodine batteries, integrated battery.