Preparation And Study Of Tin And Bismuth Composites As Anode Materials For Lithium / Sodium Ion Batteries

At present,the development of green,renewable and sustainable clean energy is considered essential to alleviate environmental pollution problems.Lithium-ion batteries(LIB)are widely used in mobile devices,vehicles and large-scale grid energy storage equipment in life and technology.This is because of its high energy density,clean and efficient.At the same time,because sodium is rich in natural resources,low in price,and similar in nature to lithium,it can perfectly solve the high cost problem caused by insufficient lithium reserves in the near future.Electrode materials are a key factor in determining the performance of lithium/sodium ion batteries(SIB).Therefore,new materials and systems are constantly being developed,which has enabled the battery industry to develop extremely fast.Among them,the anode material of alloy mechanism and transformation mechanism has better safety and higher specific capacity,but the electrode material is easy to be powdered and fragmented,which reduces the battery life.This article will address this problem and develop lithium/sodium ion battery anode materials.Modification research,the research content is as follows:The second chapter introduces another heterostructure composite material composed of SnO₂,ZnS and mesoporous carbon material CMK-3.Metal oxides and metal sulfides are both excellent battery anode materials,and both have higher theoretical capacity.However,in actual use,changes in material volume will cause rapid capacity decay and poor cycle stability.Mesoporous carbon cmk-3 is a good conductive material and support material,and it performs very well when used as a battery anode material.We specially compound SnO₂ and ZnS with mesoporous carbon material CMK-3,and embed SnO₂ and ZnS in the holes of mesoporous carbon material CMK-3,which greatly enchances the cycle ability of the composite material.Using a current density of 0.1 A g^-1 in a lithium-ion battery,after 50 cycles,it has a discharge performance of 793.7 m A h g^-1,in a sodium-ion battery,after 265 cycles,it has a discharge performance of 96.1m A h g^-1 The discharge performance.Chapter 3 introduces the Bi element has shown excellent and stable performance as one of the candidates for battery negative electrode materials for lithium ion and sodium ion storage.And Bi element is one of the elements in the main group of IVA,with a high theoretical capacity,it can provide a high body energy density(3765m A h cm^-3)for lithium ion batteries and sodium ion batteries.However,there is a problem in that the volume of the alloy-type material changes greatly during the cycle,which may cause the electrode to crush and gradually reduce its specific capacity.Therefore,in Chapter 3,to solve this problem,porous carbon and Sn are selected as the buffer layer of Bi to construct a heterostructure.The Sn element has a theoretical storage capacity of 990 m A h g^-1 as a LIB anode material,and a theoretical storage capacity of 850 m A h g^-1 as an SIB element.The composite material(Bi/Sn@3D-C)prepared by inserting the two into three-dimensional porous carbon has obtained excellent performance as an electrode material specially used for energy storage of lithium ion and sodium ion batteries.In addition,the cycle performance of Bi/Sn@3D-C,Bi@3D-C and Sn@3D-C was compared.The discharge capacity of Bi/Sn@3D-C remains 632.0 m A h g^-1(0.1 A g^-1)after 120 lithium-ion storage cycles,and after 50 cycles in a sodium-ion battery,The specific capacity of the electrode reaches 291.5 m A h g^-1.