Preparation And Electrochemical Performance Of Sb₂O₄ Composites

The theoretical specific capacity of antimony-based material Sb₂O₄is as high as 1227 m Ah g^-1, and it is expected to replace graphite as a new lithium-ion battery anode material,which has attracted the attention of researchers.However,in the practical application of Sb₂O₄electrodes,there are two key scientific problems need to be solved:（1）volume expansion:during repeated charging and discharging,antimony-oxygen materials and lithium ions continuously undergo de/intercalation reactions,and the continuously formed SEI film will Cause huge volume expansion（usually up to 300%-400%）.The mechanical stress generated by this volume expansion destroys the structure of the battery,causing the battery capacity to decline sharply;（2）Poor conductivity:antimony-based oxides have poor conductivity,and when used as an electrode material,it will hinder lithium ions between the positive and negative electrodes transport,increasing the charge transfer impedance of the battery.Therefore,how to suppress its volume expansion and improve its conductivity is extremely challenging.Focusing on these two key scientific issues,this paper designs and constructs antimony oxide-based composite materials,aiming to inhibit its volume expansion,improve conductivity,and improve battery performance.The specific work is as follows:（1）Controllable preparation and characterization of antimony oxide nanorods.Using Sb Cl₃and I₂as precursors,Sb₂O₄was prepared by hydrothermal method at 200℃.XRD diffraction patterns show that the product is orthorhombic Sb₂O₄.SEM characterization revealed that the as-prepared Sb₂O₄was a nanorod with a diameter of 75-120 nm and a length of 200-450 nm.（2）Preparation and characterization of metal-organic frameworks.Using 2-dimethylimidazole as the organic ligand and Co（NO₃）₂·6H₂O as the precursor,the metal-organic framework was carried out by room temperature solution method on carbon cloth after cleaning and plasma treatment（300W,20min）.The growth of the framework is followed by high-temperature annealing at up to 650℃in N₂to further enhance the stability of the metal-organic framework structure.Finally,etching is performed to remove Co in the sample and form a carbon framework/carbon cloth（C/CC）composite structure.（3）Preparation and electrochemical performance of Sb₂O₄nanorods@carbon skeleton/carbon cloth（Sb₂O₄@C/CC）composites.On the basis of the above work,Sb₂O₄nanorods@carbon skeleton/carbon cloth（Sb₂O₄@C/CC）composites.And systematically study its electrochemical performance.The electrochemical performance of Sb₂O₄@C/CC is significantly better than that of C/CC,and its initial specific capacity is as high as 1616.1 m Ah g^-1at a current density of 0.1 A g^-1,and it is still reversible after 100 cycles.The capacity can still be maintained at 1161.5 m Ah g^-1,close to the theoretical specific capacity of Sb₂O₄,which is better than the reported Sb₂O₄-based composites.At a current density of 1 A g^-1,the discharge specific capacity is as high as 708.1m Ah g^-1,and after 300 cycles,the capacity remains at 686.3 m Ah g^-1,which is close to 71.5%of the initial capacity.Even at a high current density of 3 A g^-1,the Sb₂O₄@C/CC electrode can still exhibit a reversible capacity of 311.3 m Ah g^-1.The improvement of the electrochemical performance of the Sb₂O₄@C/CC composite material is due to the comprehensive effect of Sb₂O₄,carbon skeleton and carbon cloth:the composite structure has good conductivity,and the electron transfer resistance of the composite electrode is only 18.9Ω,which is much smaller than C/CC;antimony oxide nanorods are embedded in the carbon skeleton of the derivative of the metal organic framework,the volume expansion is suppressed during the charge and discharge process,and it also maintains the stability of the battery structure,and the carbon cloth helps to improve the conductivity of the composite material.