Preparation Of Tin Based/MOFs Materials And Their Modification To The Anode Electrode In Lithium Batteries

The anode materials of lithium-ion battery are the key component that affects the performance of battery.At present,the negative materials mainly include carbon,tin,lithium and transition metal oxides,which have very high theoretical specific capacity.However,these materials have the problems of volume expansion,the capacity fading or the short-circuit of the battery caused by dendrite lithium.Therefore,this paper with the purpose of improving the cycling stability of anode materials and ensuring the high capacity of the metarials to prepare composite nanomaterials with special structures,in order to improve the electrochemical performance of lithium-ion batteries.This article is divided into five chapters.In Chapter 1,we point out the research background,introduce the research progress of metal organic frameworks,and explain the properties,modification methods and preparation methods of anode materials in the lithium-ion battery.In Chapter 2,a series of Mn_xCo_0.5-xSn_0.5O₂(x=0.00,0.15,0.25,0.35,0.50)and Sn O₂porous nanofibers and nanoparticles were prepared through a single-spinneret electrospinning technique followed by a calcination process.The results showed that porous nanofibers had better performance when doped with manganese and cobalt components.With the increase of manganese contents,the electrochemical capability of the batteries was improved.As a demonstration,the Mn_0.50Co_0.00Sn_0.5O₂(x=0.50)porous nanofibers presented the first discharge capacity of 1347.3m Ah g^-1,and after 100 cycles,Mn_0.50Co_0.00Sn_0.5O₂possessed the higher discharge capacity of 131.6m Ah g^-1when compared to the other materials.In Chapter 3,the strategy of doping the metal Mn on the Sn O₂to synthetize the Mn_0.5Sn_0.5O₂composite nanofibers with the inconspicuous effect on batteries electrochemical performance,while the Metal-organic frameworks(MOFs)and their derivatives with well defined structures show the great potential to enhance the electrochemical performance.So we designed the Mn_0.5Sn_0.5O₂nanofibers embedded with Co-based MOFs particles(ZIFs-67 derivative particles)to use as anode materials in lithium-ion batteries.It was found that the well designed composite nanofibers showed excellent lithium storage properties and cycling stability.The Mn_0.5Sn_0.5O₂NF/Co-based MOFs electrode delivered the high initial discharge and charge capacities of 1620.01and 1198.92 m Ah g^-1,respectively,with a 74.0%coulombic efficiency,and maintained a higher discharge/charge capacities of 412.12 m Ah g^-1/407.41 m Ah g^-1at a current density of 100 m A g^-1after 80 cycles.In Chapter 4,we proposed a novel interlayer with 3D network which was rich in the N-containing functional groups and Co nanoparticles to guide the uniform Li nucleation/growth thus relieved the Li dendritic formation.As a result,the as-designed composite delivered an ultra-long lifespan of 1500 h with a small and stable voltage profile of 38.1 m V for the symmetric cells.The composite electrode also exhibited prominent electrochemical performance in full cells with Li Fe PO₄as the cathode for lithium ion batteries(LIBs).In Chapter 5,a brief summary of the specific research results of this paper.