Structural Optimization Of Vanadium-based Nanomaterials And Their Application In Zinc Ion Batteries

Energy-related research is critical to the development of our country due to the intensifying energy crisis and growing environmental pollution.Aqueous zinc ion batteries（ZIBs）stand out among many new energy storage devices due to their high theoretical specific capacity（820 m Ah/g）,low redox potential（-0.76 V）,and high abundance.Despite its broad prospects,there are still many challenges to be addressed in the positive electrode materials of zinc ion batteries.For example,the dissolution of materials during charging and discharging processes,and unclear storage mechanisms.In this paper,we will take vanadium-based materials as the main research object,prepare two vanadium-based compounds by hydrothermal method,and reveal the zinc storage mechanism of the materials in the electrochemical process by ex-situ X-ray diffraction（XRD）characterization.The specific research content is as follows:（1）Synthesis of high-rate performance VS₂nanomaterials and their application in zinc ion batteries.VS₂nanosheets were synthesized by hydrothermal reaction in ammonia using thioacetamide as the sulfur source and ammonium metavanadate as the vanadium source.The graphene-like structure of VS₂was utilized to enable fast embedding/de-embedding of zinc ions in a wide layer spacing（5.76?）and enhance the reversibility of the reaction.Ultimately,a high initial capacity of 148.4 m Ah/g can be obtained for the prepared VS₂nanosheets at a current density of 0.2 A/g.The capacity can also reach 121.2 m Ah/g at a relatively large current density of 1 A/g with a capacity retention of 82%,reflecting an excellent rate performance.（2）Synthesis of oxygen-defected Al-dopping VO₂nanoribbons and their application in zinc ion batteries.oxygen-defected Al-dopping VO₂nanoribbons were prepared by hydrothermal method.The electrochemical test results showed that the discharge capacity of the VO₂nanoribbon cathode was 275 m Ah/g at a current density of 0.2 A/g.The capacity retention rate was over 80%at a current density of0.5 A/g for 150 cycles.Compared with pure VO₂nanoribbons,the specific capacity and cycling retention rate are significantly improved.Effective Al intercalation will help to improve the structural stability of the material as confirmed by various characterization tools and data analysis.This optimized structure ensures the reversible phase transition of the material during ion embedding/de-embedding.In addition,the combination of ex-situ XRD characterization reveals the structural evolution of the material during electrochemical testing.This strategy provides a good basis for the subsequent construction of electrode materials for high-specific energy Zn-ion batteries.