Iron-based Metal Oxides As Sulfur Loading Matrix For Lithium-sulfur Batteries And Electrochemical Performance Analysis

In recent years,with the explosive growth of electrical energy consumption,rechargeable lithium-ion batteries have penetrated into all aspects of modern society.However,the specific capacity of the traditional positive electrode material and negative electrode material based on the insertion mechanism is close to the theoretical limit.Therefore,people have high expectations for new battery chemistry technologies other than lithium-ion batteries.As the most promising next-generation energy storage battery,lithium-sulfur batteries have high expectations.Among them,the most stable but electronically insulated cyclic configuration S8 is used as the starting material of the lithium-sulfur battery cathode,which greatly limits the full utilization of the active material,and it is difficult to achieve the theoretical capacity.Therefore,the design of the cathode must first ensure the maximum utilization of raw materials.This paper mainly explores iron-based metal oxides as cathode materials for lithium-sulfur batteries and their electrochemical performance analysis.First,the nano-scale iron oxide（Fe₂O₃）is synthesized by hydrothermal method and prepared into electrode material.Experiments show that the material has a large specific surface area,has a great adsorption effect on sulfur,and can improve its electrochemical performance.When the hydrothermal time is 2h and the sulfur loading is 1:3,the capacity decay of the electrode material is the lowest.After 200 cycles,the capacity retention rate is 77%,indicating that the material has excellent cycle stability.In order to further improve the sulfur adsorption capacity of the matrix material,the hydrothermal method is still used to prepare Cu-doped Fe₂O₃（Cu@Fe₂O₃）with different mass ratios as the sulfur-carrying matrix material,and after sulfur loading,the Cu@Fe₂O₃/S composite electrode material is obtained.Through physical and chemical test and analysis,it can be seen that when the sulfur loading ratio is 1:3,the Cu doping ratio is 1:1.5,and the hydrothermal temperature is 150℃,the Cu@Fe₂O₃ composite electrode material has the highest battery specific capacity,at0.2C The capacity retention rate after 200 cycles at the current density can reach 45.7%;when the sulfur loading ratio is 1:4,the Cu doping ratio is 1:1.5,and the hydrothermal temperature is 170℃,the Cu@Fe₂O₃ composite electrode material has the highest The specific capacity of the battery,the capacity retention rate after 200 cycles at 0.2C current density is as high as 69.3%;when the Cu doping ratio is 1:1 and the hydrothermal temperature is 190℃under the high sulfur load of 1:5The Cu@Fe₂O₃ composite electrode material has the highest battery specific capacity,and the capacity retention rate can reach 66.6%after 200 cycles at 0.2C current density;it proves that the doped material has good cycle stability.Finally,nano-scale Fe₂O₃ is synthesized by vacuum arc method.The obtained nano-scale Fe₂O₃ nanoparticles and sulfur are mixed in different proportions to make electrode pole pieces,which are used as the positive electrode of the lithium-sulfur battery.The porous Fe₂O₃ acts as an internal polysulfide container,thereby reducing the shuttle effect.The charge and discharge test results show that the specific discharge capacity of the cathode is the highest when the sulfur content of the Fe₂O₃-arc matrix material is 1:3.The current initial discharge specific capacity can reach 720.59 m Ah,653.79 m Ah and 540.32 m Ah·g^-1 at rates of 0.1,0.2 and 0.5 C,respectively.The cathode has the highest discharge voltage plateau.This also proves that the nano-Fe₂O₃-arc matrix material can reduce the polarization resistance of the sulfur-loaded composite active material and increase its electrochemical reaction rate.