Constructed For The Photo-Assisted High Energy Density Aqueous Batteries Based On Semiconductor Photoelectrodes

In the face of increasingly severe global energy shortages and environmental pollution,researchers from various countries are actively developing and transforming the efficient use of renewable energy.Through the photocatalysis of semiconductor photoelectrodes,converting solar energy into chemical energy stored in reaction products is a new type of solar energy conversion method,especially storing solar energy in rechargeable batteries which are high energy density,high safety,and development rapidly has become the future trend of energy development.Semiconductor photoelectrodes are an important part of photoelectrochemical cells.The microscopic morphology and structure of photoelectrodes play a vital role in photo absorption and photogenerated carrier transport,affecting the electrochemical performance of photoelectrochemical cells.In this dissertation,TiO2 photoelectrodes with high photoelectrochemical properties were prepared mainly through the control of micromorphology.At the same time,Pt/CdS photoelectrodes that can simultaneously catalyze polysulfides and decompose water to produce hydrogen.The photoelectrodes were integrated into high-energy aqueous batteries which can achieve the conversion and storage of solar energy and save power.The morphology of the TiO2 photoelectrode was explored by adjusting the preparation method and the temperature and time during the preparation.It was found that the TiO2 nanorod had the best photoelectrochemical performance.Through further structural characterization and in-depth analysis,the reason for the excellent photoelectrochemical performance of TiO2 nanorods can be attributed to having a more negative flat band potential and thus a higher Fermi level.By electrochemical testing of an aqueous Zn-I battery based on a TiO2 nanorod photoelectrode,at a current density of 0.01 mA cm-2,the charging voltage is 0.56 V under illumination,which could save nearly 56.6%of electricity during photoassisted charging process.Based on the research of traditional aqueous Al-S battery with high specific energy,high safety and low cost,a photo-rechargeable aqueous Al-S battery based on Pt/CdS photoelectrode was constructed.By modifying the aluminum negative electrode and electrolyte of aqueous Al-S battery,the measured specific discharge capacity of the battery at a current density of 0.2 mA cm-2 reached 1112.7 mAh g-1,which is 98.3%of the theoretical specific capacity.This is mainly due to the zirconium-based protected film on the surface of the aluminum negative electrode(the main components are Na3AlF6,Zr(HPO4)2 H2O,ZrO2,AlPO4)and In(OH)3 and Na2SnO3 in the electrolyte,which slows the aluminum corrosion in electrolyte.The Pt/CdS photoelectrode is introduced into an aqueous Al-S battery.The photo-generated holes generated by the Pt/CdS photoelectrode under illumination conditions oxidize S2-to S42-to achieve the charging process of the battery,and the photo-generated electrons are used for producing hydrogen.The discharge test was performed on the photo-charged aqueous Al-S battery,at a current density of 0.3 mA cm-2,the discharge capacity reached 458 mAh g-1 after 150 min photo-charge,and the discharge capacity was 60 mAh g-1 after 20 min photo-charge,and it remains stable during a 10 cycle.It proves that the photo-charged aqueous Al-S battery can be cyclically charged and discharged.As far as the rapid development of hydrogen storage technology is concerned,it can provide certain support for the aerospace,automotive and other fields that require hydrogen energy.