Research On Hydrothermal Method And Electrochemical Properties Of MoO₃

Because of the excellent performance, Lithium ion secondary battery became theworld’s favorite since it was developed, but the electrical performance of lithium ionbattery was affected by the appearance and structure of the anode materials to a largeextent. The diffusion mechanism of Li+became the bottleneck restricted itsdevelopment. There are tetrahedral and octahedral cavity in the lattice structure ofmolybdenum oxide and the channel size in the structure is suitable for insertion andout of the small ion, so molybdenum oxide showed good lithium intercalationproperties. Molybdenum trioxide have been widely applied in many fields，such aslithium ion secondary batteries，catalysts, electrochromic materials because of theirtypical two-dimensional layered structure.This paper focused on studying molybdenum trioxide powders which wereprepared by hydrothermal synthesis method, and its electrochemical properties werealso studied based on the relevant knowledge about assembly and testing of lithiumbattery. Modern testing methods were used to compare with the influence of differentpreparation methods on MoO₃phase structure and the different electrochemicalperformances of molybdenum trioxide in different phases. Molybdenum trioxidepowders were modified by Li+to improve circulatory performance of the material. Themain research contents and research results were as follows:1.Using a simple hydrothermal method, hexagonal molybdenum trioxideorthorhombic molybdenum trioxide can be synthesized with ammoniumheptamolybdate as the raw material without template. Hexagonal MoO₃was changedto orthorhombic MoO₃when calcination temperature is about400℃.2. Under the condition of pH=1and the heat treatment temperature reached170℃,crystal morphology of hexagonal phase molybdenum was changing with the timeextension and process of the crystal dissolving–recrystallization. After25hrs heattreatment, hexagonal micron columnar molybdenum trioxide can be generated. Morphology of molybdenum trioxide gradually became threadiness from columnar asthe acidity increased, and while the acidity coefficient is30, all fibrous basically with20³0μm in length.3. The initial discharge capacity of h-MoO₃was171.4mAh·g-1and kept95.6mAh·g-1after20cycles with capacity retention was55.8％. The initial dischargecapacity of h-MoO₃was171.4mAh·g-1and kept95.6mAh·g-1after20cycles withcapacity retention was55.8％, so the electrochemical performance of α-MoO₃wasbetter than h-MoO₃.4. Appearance of MoO₃powders was not changed much after it was lithiated. Theinitial discharge capacity of LixMoO₃was205.5mAh·g-1and kept144.3mAh·g-1after20cycles with capacity retention was70.2％.