Preparation And Research Of Vanadium-based Compounds As Cathode Material For Aqueous Zinc Ion Battery

As a new generation of new batteries,aqueous zinc ion batteries have received extensive attention in the international community because of their lower manufacturing costs,high safety in use,and better environmental protection.For aqueous zinc-ion batteries,the main challenge that hinders their commercialization comes from the development of electrode materials.Among them,whether the cathode material has excellent electrochemical performance is a key condition for the commercialization of aqueous zinc ion batteries.Therefore,this article discusses the modification of vanadium pentoxide（V₂O₅）nanoribbons by adding conductive substances by hydrothermal method;on the other hand,the modification of vanadium pentoxide（V₂O₅）by sodium ion doping by hydrothermal method.At the same time,conductive materials are added to modify the samples.The specific research content is roughly divided into the following two parts.（1）Through a simple hydrothermal reaction,a composite nanomaterial of vanadium pentoxide（V₂O₅）nanobelt and redox graphene（rGO）was successfully prepared.A series of morphological structure and phase structure characterizations were carried out on the V₂O₅ nanobelt/rGO composite material.The results show that the composite material of V₂O₅nanobelt and rGO has been successfully prepared.Commercial grade V₂O₅ and V₂O₅ nanobelt and rGO composite material are two vanadium-based materials as the positive electrode for the electrochemical test.commercial V₂O₅ has also been used for comparing the battery’s performance with the V₂O₅-rGO（Reduced graphene oxide）nanocomposite products.The commercial V₂O₅showed poor cycle stability and low specific capacity 30 mA h/g specific capacity was observed after 200 cycles,while the V₂O₅nanobelts/rGO composite showed good performance.When a current density of 0.1A/g was applied to the coin cell used for testing,the V₂O₅ nanobelts/rGO showed excellent cycle stability and a high specific capacity of 135 mA h/g after 200 cycles.In the rate performance,when a current density of 1 A/g is applied,a high specific capacitance of 113 mA h/g can be obtained.Compared with the commercial V₂O₅,V₂O₅nanobelts/rGO composite depicts superior performance as an electrode material for aqueous zinc ion batteries.（2）A simple hydrothermal synthesis method was used to successfully prepare sodium vanadate(Na_0.33V₂O₅)nanosheets and Ordered mesoporous carbon（CMK-3）composite materials.The modification method is to add metal sodium ions and conductive material Ordered mesoporous carbon.Through XRD and SEM test analysis,the morphology and phase of the samples were characterized.Two vanadium-based oxide pure Na_0.33V₂O₅ nanosheets and a composite of Na_0.33V₂O₅ nanosheets and CMK-3 were used as cathode materials for electrochemical analysis and testing.The results show that compared with industrial-grade vanadium pentoxide nanosheets and Na_0.33V₂O₅nanosheets,Na_0.33V₂O₅ nanosheets and CMK-3 composites have lower charge transfer resistance.Also,after 100 cycles of Na_0.33V₂O₅ nanosheets and CMK-3 composites at a current density of 1 A/g,the specific capacity remains around 80 mA h/g.After applying a current density of 0.1 A/g,after 50 cycles,the battery’s charge-discharge specific capacity remained around 120 mA h/g.The results showed that compared with commercially available V₂O₅ and Na_0.33V₂O₅ nanosheets,The composite material of Na_0.33V₂O₅ nanosheets,and CMK-3 has a higher specific capacity.The specific capacity of Na_0.33V₂O₅ nanosheets is more stable than that of industrial-grade vanadium pentoxide.Therefore,the electrochemical performance of vanadium-based materials can be improved by introducing metal ions and adding conductive materials.