Molybdenum Oxide As Negative Electrode Material For Aqueous Al-ion Batteries

Aqueous aluminum ion batteries have become a hot spot for research because of the good safety performance,simple production and non-toxic electrolyte,high ionic conductivity and environmental friendliness.This paper is focused on molybdenum trioxide.The electrochemical properties in aqueous aluminum ion batteries were explored.Optimizing electrochemical performance of aluminum storage by structural control.The main contents include:1.MoO₃ nanobelts.MoO₃ nanobelts were obtained by using molybdenum powder as raw material,H₂O₂ as oxidant,and high-temperature hydrothermal treatment.The electrochemical properties of MoO₃ nanobelts were measured in 1 mol L^-1 Al Cl₃.These results of CV suggest that the redox peaks result from the Al³⁺ions.MoO₃ nanobelts can be used as the negative electrode material for aqueous aluminum ion batteries.At 1 A g^-1,MoO₃ nanobelts maintains49.2 mA h g^-1 after 5000 cycles.MoO₃//rGO battery exhibited a stable capacity of 65.6 mA h g^-1 after 20,000 cycle at 5 A g^-1?The capacity were calculated based on the MoO₃ nanobelts?.2.MoO_3-x nanobelts.We develop oxygen-deficant MoO_3-x nanobelts using ethanol as reducing agent with hydrothermally at high temperature.The presence of oxygen vacancies increases the ion diffusion channels and electrical conductivity,and effectively improves the aluminum storage performance.By adjusting the reduction temperature,different levels of oxygen vacancies can be obtained.After comparison optimization,MoO_3-x-110 nanobelts showed the best electrochemical performance.At 1 A g^-1,MoO_3-x-110 nanobelts maintains 88.6mA h g^-1 after 5000 cycles.MoO_3-x//rGO battery maintains 144.5 mA h g^-1 after 20000 cycles at 5 A g^-1,which is much higher than the capacity retention of 65.6 mA h g^-1 for the MoO₃//rGO battery.3.MoO₃@PPy nanobelts composite.Using ammonium persulfate as an initiator,MoO₃@PPy nanobelts composite was prepared by an ice-water bath.The PPy layer effectively stabilizes the structure of the nanobelts and significantly improves the cycle performance of the MoO₃ nanobelts.By adjusting the pyrrole monomer content,the thickness of the PPy layer can be controlled.After comparison optimization,MoO₃@PPy-0.05 nanobelts composite showed the best electrochemical performance.At 10 A g^-1,MoO₃@PPy-0.05 nanobelts composite has an initial capacity of 135.1 mA h g^-1.MoO₃@PPy-0.05 nanobelts composite maintains 65.5%of the capacity after 2000 cycles,which is much higher than the 17.3%for the MoO₃.At 5 A g^-1,MoO₃@PPy-0.05//rGO battery maintains 72.4%of the capacity after 15000 cycles,which is much higher than the 58.4%for the MoO₃//rGO battery.