【作者】 王欢；

【导师】 曾敏；

【作者基本信息】 西南科技大学 ， 材料科学与工程， 2021， 硕士

【摘要】 目前锂离子电池作为新型的环境友好的储能电池,在能量密度和安全性能上已经不能够满足人们的需求。而要提高锂离子的性能,主要还在于改进锂离子的电极材料。MOFs本质上的多孔结构使电解质渗透和离子传输变得容易,而组分的可设计性则保证了电活性位点的结合,为不同电池系统寻找候选电极材料提供了无限的可能性。本论文通过水热法和共沉淀法分别合成了铜基单金属及钴基单金属MOF,并分别利用Co²⁺、Zn²⁺和Mg²⁺、Ni²⁺取代单金属MOF中的Cu²⁺和Co²⁺合成双金属MOF,改善单金属MOF的电化学性能。研究内容如下:（1）通过水热法一步合成HKUST-1 MOF材料,通过调控煅烧条件获得不同的MOF衍生物材料Cu₂₊₁O/Cu@C和Cu₂₊₁O/Cu O@C,作为锂离子电池的负极材料350-10-0显出最优的电化学性能。350-10-0在200 m A/g的电流密度下经过200次循环后容量提升至526 m Ah/g。（2）引入了Co²⁺、Zn²⁺部分取代HKUST-1中的Cu²⁺并进行热处理,成功的合成了MOF衍生物材料Cu-Co@C和Cu-Zn@C,改善单金属Cu₂₊₁O/Cu O@C的电化学性能。Cu-Co@C、Cu-Zn@C在200 m A/g的电流密度下循环200次后容量分别达到835 m Ah/g、573 m Ah/g高于单金属MOF衍生物350-10-0的526m Ah/g。这是由于相对于单金属MOF来说多金属MOF材料中由于存在多种金属氧化物,所以在充放电的过程中不仅可以通过分段的锂插入/脱出过程来缓解体积变化,而且提供了更高的电导率和丰富的氧化还原活性中心,有利于提高材料的整体电化学性能。（3）通过共沉淀法成功的制备了一元单金属MOF材料ZIF-67,并且采用Mg²⁺、Ni²⁺取代部分Co²⁺成功制备了双金属MOF材料,通过高温热处理成功合成了Co₃O₄@C、Ni Co₂O₄@C和Mg Co₂O₄@C。在500 m A/g的电流密度下经过200次循环后,Co₃O₄@C的比容量仅有227 m Ah/g,而双金属Ni Co₂O₄@C和Mg Co₂O₄@C的比容量在200次循环后没有下降,反而增加;这是由于相对于单一金属ZIF-67中生成的一元尖晶石结构的Co₃O₄来说,双金属MOF中生成的Ni Co₂O₄和Mg Co₂O₄本质上是二元尖晶石结构,这种尖晶石型的过渡金属氧化物拥有更高的电子电导率、更大的比容量以及更高的电化学活性。更多还原

【Abstract】 At present,as a new environment-friendly energy storage battery,lithium ion battery has been unable to meet the needs of people in terms of energy density and safety performance.In order to improve the performance of lithium ion,it is mainly to improve the electrode materials of lithium ion.The porous nature of MOFs facilitates electrolyte penetration and ion transport,while the design of the components ensures the binding of electroactive sites,providing unlimited possibilities for finding candidate electrode materials for different battery systems.In this paper,copper based and cobalt based mono-metal MOF were synthesized by hydrothermal method and co-precipitation method respectively,and bimetallic MOF were synthesized by replacing Cu²⁺and Co²⁺in mono-metal MOF with Co²⁺,Zn²⁺,Mg²⁺and Ni²⁺,respectively,to improve the electrochemical performance of mono-metal MOF.The research contents are as follows:（1）HKUST-1 MOF was synthesized by hydrothermal method in one step,and different MOF derivatives Cu₂₊₁O/Cu@C and Cu₂₊₁O/Cu O@C were obtained by adjusting the calcination conditions.350-10-0 as anode material of lithium ion battery showed the best electrochemical performance.The capacity of 350-10-0 is increased to 526 m Ah/g after 200 cycles at the current density of 200 m A/g.（2）Co²⁺and Zn²⁺were introduced to partially replace Cu²⁺in HKUST-1 and heat treated.The MOF derivatives Cu-Co@C and Cu-Zn@C were successfully synthesized to improve the electrochemical properties of mono-metal Cu₂₊₁O/Cu O@C.After 200 cycles at the current density of 200 m A/g,the capacities of Cu-Co@C and Cu-Zn@C can reach 835 m Ah/g and 573 m Ah/g respectively,which are higher than that of 526 m Ah/g of the mono-metal MOF derivative 350-10-0.This is due to the existence of multiple metal oxides in multi metal MOF materials,so in the process of charging and discharging process can not only through the segmentation of the lithium insertion/out to relieve the volume change,and provides a higher conductivity and rich REDOX active center,to improve the overall electrochemical properties of the material.（3）The mono-metallic MOF material ZIF-67 was successfully prepared by co-precipitation method,and the bimetallic MOF material was successfully prepared by Mg²⁺and Ni²⁺replacing part of Co²⁺,and Co₃O₄@C,Ni Co₂O₄@C and Mg Co₂O₄@C were successfully synthesized by high temperature heat treatment.After 200 cycles at the current density of 500 m A/g,the specific capacity of Co₃O₄@C is only 227 m Ah/g,while the specific capacity of bimetallic pole and A does not decrease after 200 cycles,but increases.This is due to the fact that Ni Co₂O₄and Mg Co₂O₄generated in bimetallic MOF are essentially binary spinel structures compared with Co₃O₄with monominel structure generated in a single metal ZIF-67.Such spinel-type transition metal oxides have higher electronic conductivity,larger specific capacity and higher electrochemical activity.更多还原