Abstract
The catalysts for lithium-oxygen batteries have been researched for decades due to the huge energy storage ability. However, the sluggish catalytic performance towards the decomposition of discharge products (Li2O2) inspires us to utilize the photo-generated holes to overcome the obstacle. As novel energy storage device, the TiO2 nanorod arrays on carbon textiles were well-designed and adopted as both air cathode and photo-anode for photo-assisted Li-O2 batteries. Electrochemical data strongly demonstrate that the abundant photo-generated holes on the TiO2 can efficiently oxidize the Li2O2 (the charge potential reduced from 4.31V to 2.86V vs Li/Li+). It is noted that the light illumination prompts the TiO2 to be more defective and the generated oxygen vacancies further enhance the electron and Li+ migration, leading to the improved ORR performance (discharge potential at 2.85V vs Li/Li+). The batteries can charge/discharge for 30 cycles with no decay and deliver the excellent rate performance.
The photo-generated holes from defective TiO2 can directly oxide the discharge products (Li2O2) and thus bring the charging potential of the Li-O2 batteries down to 2.86V. The cycling process further makes the TiO2 more defective, enhancing the ORR performance and promoting the electron and Li+ migration. [Display omitted]