Research On The Positive Material Of Sb₂Se₃ Based Aluminum-ion Battery

At present,in the existing secondary battery system,aluminum ion batteries are widely studied in the field of chemical energy storage because of their rich resources and high safety,which also makes aluminum ion batteries likely to be the next generation energy storage system.The positive electrode material in aluminum ion batteries is one of the key materials that affect the energy density,power density,and cycle life of the battery.Among the existing battery materials,graphite material can be considered as an ideal positive electrode material because of its high discharge platform and better cycle performance,but its stable capacity is lower,which further limits the development of aluminum ion batteries.Therefore,the development of battery systems with high voltage,high capacity,and good cycle performance will become a research hotspot in the field of batteries.Based on previous studies,this paper conducted detailed electrochemical performance tests and mechanism studies on aluminum-based positive materials?antimony selenide and its composite materials?using[EMIm]Cl ionic liquid as the electrolyte.The results are as follows:?1?Sb₂Se₃ nanomaterials were successfully synthesized by solvothermal method.Through SEM and TEM characterization,it is found that Sb₂Se₃ is a single-crystal nanorod structure,and the diameter of the nanorod is about 400 nm.The specific surface area obtained using the BET method is 1.954 m2 g-1.In addition,using the BJH method,a large number of mesopores are centered at?4.204 nm,and the mesopore volume is 0.017 cc g-1.When Sb₂Se₃ is used as the positive electrode material for aluminum ion batteries,obvious redox reactions occur at 1.2/0.7 V,1.5/1.6 V,and 2.1/1.7 V.Conduct a constant current charge and discharge test on the assembled aluminum ion battery.At a current density of 500 mA g-1,the first-cycle charge and discharge curves are not completely consistent with the subsequent charge-discharge curves.The initial charge/discharge capacities of Sb₂Se₃ were measured to be 387.4 mA h g-1 and 229.4 mA h g-1,while the Coulomb efficiency is only 59.2%.After 100 cycles,the discharge specific capacity stabilized at 48 mA h g-1 and the Coulomb efficiency stabilized at around 90%,showing good cycle stability.?2?The solvothermal method was used to synthesize Sb₂Se₃-based composite materials at 180?,and their physical and chemical characterization was performed by means of XRD,SEM,TEM,etc.,confirming the existence of graphene oxide and its induction as a template.The modified separator was successfully prepared by vacuum suction filtration.Using this improved separator in an aluminum ion battery can effectively suppress the problem of active material dissolution,thereby improving the stable discharge specific capacity.Nitrogen doping can improve the active site of the material.Sb₂Se₃ composite N-doped reduced graphene oxide is used as the aluminum ion cathode material,and after using a self-made modified separator,it passes 500 cycles at a current density of 500 mA g-1 After the cycle,the discharge specific capacity can reach 120 mA h g-1.At a current density of 1000 mA g-1,after 1000 cycles,the discharge specific capacity can reach 110 mA h g-1,while having a good Magnification performance.?3?When the anode material of the aluminum ion battery uses Sb₂Se₃,the electrode process is controlled by the charge transfer and diffusion process,and the electrode reaction kinetics?charge transfer process?is controlled in the high-frequency region.As the cycle goes on,the charge transfer resistance increases slightly.The low frequency region is controlled by the diffusion of reactants or products reacted by the electrode.The reaction mechanism of Sb₂Se₃ as a positive electrode material for aluminum ion batteries was speculated by means of XPS,XRD,and Raman.During the charging process,the negative divalent Se will undergo an oxidation reaction to generate elemental selenium.During the discharge process,the elemental Se will undergo a reduction reaction to generate negative divalent Se.In addition,the positive trivalent Sb will be reduced to zero Sb.The negative electrode is Al2Cl7-during the charging process to get three electrons to generate AICl4-and Al,and the discharging process is the opposite.