| 研究実績の概要 |
The aqueous lithium redox flow batteries are promising in terms of performance, energy density and operation efficiency. Further integrating solar power on this energy system could only be beneficial in both an operational and economical point of view. We demonstrate a novel two-electrode carbon free solar stimulated aqueous Li-I2 battery device, which in situ stores electricity using an aqueous I-/I3- redox couple through the integration of a hematite photoelectrode at the cathode. Under illumination, the electrons and holes stemmed from the absorption of photons are separated in the space charge layer and accumulate within the hematite photoelectrode. The maximum voltage delivered by the cell is more negative under illumination (Ecell sun = 3.4 V vs Li/Li+) than in dark (Ecell dark = 3.55 V vs Li/Li+) due to this charge injection. The aqueous two-electrode photoassisted battery exhibited robust behavior for 30 cycles (~400 h) with coulombic efficiencies of ~99.2% and energy efficiencies of 85%. The high capacity retention (99.5%) indicates that the battery is capable at operating with minimal capacity fade (Q = 205 mAh.g-1) while a gravimetric energy density of 0.6 Wh.kg-1 was achieved analogous to other EES systems. The attested operation of the solar stimulated aqueous Li-I2 battery suggests that the successfully integrated hematite photoelectrode can scavenge quantitatively the photogenerated charge carriers.
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