Study On Preparation And Potassium Storage Performance Of Antimony-based Anode Materials For Potassium Ion Batteries

Potassium ion processes larger ion radius than lithium ion,and its slow reaction kinetics limits the potassium storage performance of the anode materials of potassium ion batteries,so the modification of anode materials has become a hot spot in research.Sb-based negative electrode materials have a higher theoretical specific capacity,but their large volume changes during battery charging and discharging are likely to cause problems such as electrode is powderized,low Coulomb efficiency,and poor cycle performance.Therefore,this paper mainly focuses on Sb-based anode materials.The antimony/carbon composite micro-nano material is prepared by in-situ chemical vapor deposition using soluble salts as templates,and its potassium storage properties are studied as follows:(1)Three-dimensional porous antimony embedded graphitized carbon(Sb@C)nanocomposite anode material is prepared by freeze-drying method combined with chemical vapor deposition method.The influence of parameters such as calcination temperature and carbon addition is studied on Sb@C,and the potassium storage performance of Sb@C is discussed.When the ratio of ammonium citrate to carbon source in the precursor is 14.7 g:2.5 g,7-10 nm Sb nano metal particles can be obtained which is embedded on the ultra-thin graphene carbon sheet.The Sb@C nanocomposite anode material shows good potassium storage performance.When the current density is 100 mA g-1,the reversible discharge specific capacity can reach 291 mAh g-1,and the reversible specific capacity can still reach 260 after 100 cycles.(2)A hollow sandwich selenium-antimony-carbon nanocomposite(3D Se@Sb@C)is prepared by treating Sb@C with secondary vapor deposition.The effect of sintering method on the morphology and structure of 3D Se@Sb@C is studied.The calcination of the precursor material under the open condition can obtain three-dimensional porous Se@Sb@C;the calcination under the closed condition can obtain the nanorod Sb2Se3@C.The three-dimensional porous Se@Sb@C shows a higher potassium storage performance than the nanorod Sb2Se3@C,the reversible discharge specific capacity can reach 400 mAh g-1 when the current density is 100 mA g-1,after 100 cycles It delivers a high reversible specific capacity 395.62 mAh g-1;at a higher current density(5000 mA g-1),and remains reversible specific capacity of 166.9 mAh g-1 after 5000 cycles.(3)DFT calculation shows that the diffusion energy barrier of the Sb/Se interface is smaller than that of the Sb/Graphene interface,which further explains that the Sb/Se interface is more conducive to potassium ion storage in the Se@Sb@C anode material.Cyclic voltammetry tests show that Se@Sb@C has high pseudo-capacitance characteristics,so it can obtain excellent potassium storage performance.