Preparation And Electrochemical Performance Of Tin-based Anode Materials For Lithium-ion Batteries

With the development of our society,the exploitation and utilization of new energy are more emphasized by researchers.Among them,lithium-ion batteries（LIBS）,as an energy storage and conversion device,have attracted much attention.The development of high-performance LIBS has become a consensus,and all of this is related to the electrode materials.Tin-based materials have advantages in theoretical capacity,lithium-intercalation potential,and natural reserves,and are very popular among researchers.However,the application of electrodes has problems such as volume change,low conductivity,and slow ion migration,which makes the development of high-performance tin-based electrode materials a challenge.Based on this knowledge,this article takes SnS₂ and SnO₂ as the object,improve performance and do further research on it.The details are as follows:（1）The flower-like SnS₂ nanostructures are prepared by one-step hydrothermal technology,and it can be used as anode materials for lithium-ion batteries.The results indicate that compared with bulk SnS₂ and graphite electrodes,the flower-like SnS₂ electrodes have more outstanding lithium storage performance.It shows an initial discharge and charge specific capacity of 690.58 m A h g^-1 and 578.32 m A h g^-1respectively,and the coulombic efficiency is83.7%at the current density of 100 m A h g^-1.And after 50 cycles,it still shows 500 m A h g^-1specific capacity.Meanwhile,the optimal adsorption site and migration path of Li⁺on the surface of the SnS₂ electrode were screened through first-principle calculations,and based on this result,the adsorption and migration properties of Na⁺and K⁺were further calculated.The results found that the sites where S atom position shows the best adsorption energy of-3.69 e V for Li⁺,and S-Sn-S path on the surface of SnS₂ is the lowest energy path for Li⁺migration（the energy barrier is 0.27 e V）.In addition,with the increase of alkali metal atomic radius（Li<Na<K）,its adsorption energy on the surface of SnS₂ does not change significantly,and the migration energy barrier decreases gradually.This work indicates that constructing tin-based sulfide electrode with a flower-like morphology is an effective way to improve its lithium storage performance.At the same time,this material also has good sodium and potassium storage performance and is expected to be a high-performance sodium-ion battery and potassium ion battery electrode material.（2）The C/SnS₂ composite materials were constructed using one-step hydrothermal strategy,and put it in an atmosphere containing N₂ for pyrolysis treatment.The product composition,morphology transformation and electrochemical performance changes at different pyrolysis temperatures were explored in detail.It was found that at 600℃,the product changed from the clumpy C/SnS₂ to C/SnS/SnO₂ ternary clustered nanoparticles,and its electrochemical performance was also excellent.The first discharge specific capacity of the electrode was 1978m A h g^-1 at the current density of 100 m A g^-1,and it still had a specific capacity of 638 m A h g^-1after 50 electrochemical cycles.The excellent electrochemical performance may come from the synergy effect in ternary nanoparticles and the increase in the specific surface area of the material,which provides more adsorption sites for Li⁺and accelerates the electrochemical reaction.This work shows that the construction of ternary nano-cluster particles can effectively improve the electrochemical performance of tin-based sulfide electrodes.Meanwhile,this work provides a simple method to construct ternary composite electrodes for energy storage.（3）A carbon-coated tin dioxide（C@SnO₂）nanostructure was constructed using a one-step hydrothermal method.Compared with bulk SnO₂,C@SnO₂ core-shell electrode has a better cycle stability and rate performance.The first discharge specific capacity of the electrodes is1420 m A h g^-1 at a current density of 100 m A g^-1,and it still has a specific capacity of 541 m A h g^-1after 150 cycles.In addition,at the current densities of 50,100,200,300,500 and 800 m A g^-1,the C@SnO₂ electrode show the discharge specific capacity of 1467.76,652.25,581.24,407.25,312.21 and 278.26 m A h g^-1 respectively.And when the current density returns to 50m A g^-1,the specific capacity returns to 421.24 m A h g^-1.This work shows that constructing core-shell structure is an effective strategy to improve the electrochemical performance of SnO₂electrodes.This method can be extended to other types of electrode materials and is helpful for the preparation of high-performance alkali metal ion batteries electrode materials.