【作者】 王波；

【导师】 张乾； 马春杰；

【作者基本信息】 西安理工大学 ， 材料与化工（专业学位）， 2025， 硕士

【摘要】 在诸多电化学储能装置中,超级电容器(Supercapacitors,SC)以其卓越的稳定性和高效率的能量转换以及存储系统备受关注,在新能源汽车、智能电网、不间断电源、可穿戴电子设备以及航天器和卫星等领域拥有巨大应用潜力。而超级电容器能量密度低的缺点限制了其在诸多领域的应用,开发性能良好的正极材料是优化超级电容器性能的关键方法之一。金属有机框架(MOF)凭借超大比表面积、独特孔隙结构及丰富活性位点,为电极材料的创新提供了关键突破口。本论文针对镍基金属化合物的实际比容量较低和倍率性能较差的问题,采用多种策略实现镍基MOF电极材料微观结构调控,构建不同二维纳米片杂化结构,用以开发具有高比容量和优异倍率性能的电极材料,进而实现高性能混合超级电容器的组装,具体研究内容涉及镍基MOF超级电容器正极材料的合成及表征、微观结构与电化学性能的优化、混合超级电容器的组装。研究内容如下:(1)NiCoAl-MOF正极材料的制备及电化学性能研究。通过碱刻蚀诱导离子空位形成的策略,成功构筑了具有独特结构的金属有机框架材料(MOF)。利用其部分金属在强碱性电解质中不稳定而被脱去的性质在材料表面形成空位,用以增强材料的电化学活性以及促进电子的迁移。采用溶剂热法在泡沫镍基底上原位生长NiCo-MOF和NiCoAl-MOF层状纳米片,作为超级电容器正极材料。研究中系统考察了不同Ni/Co 比例对电极材料性能的影响,结果表明,Ni7Co3-MOF电极展现出最优性能,在1Ag-1电流密度下,比容量可达953 F g-1。在此基础上,通过离子掺杂策略将Al3+引入框架结构,使其部分取代骨架中的Ni2+和Co2+金属中心。利用铝及其氢氧化物在强碱性电解质中发生反应,通过碱刻蚀处理,选择性去除骨架中的铝金属中心,从而形成空位。这种独特的结构显著提高了正极材料的放电比容量,优化了循环稳定性。实验数据显示,NiCoAl-MOF电极在1Ag-1电流密度下,比容量大幅提升至1585 F g-1。并且在10 Ag-1电流密度下NiCoAl-MOF比NiCo-MOF的容量高400F g-1。NiCoAl-MOF//AC 电容器在10 Ag-1电流密度下的初始容量为1099Fg-1,经过1000次完充放电循环后,容量保持率为98%。(2)层状Ni(OH)2转化Ni-MOF的方法探索及电化学性能研究。从低成本和高效率的角度出发,本论文学习了一种全新的MOF合成策略。通过层状氢氧化物与芳香族羧酸有机连接体发生反应,实现过渡金属氢氧化物与MOF的桥接,成功制备出具有独特结构的金属氢氧化物有机框架材料。采用溶剂热法,促使层状氢氧化物前体分别与2,6-萘二羧酸(NDC)、对苯二甲酸(BDC)两种芳香族有机连接体进行反应,成功合成两种同构MOFs。这一结果不仅证实了该合成方法在构建复杂框架结构上的可行性,也充分展现了其在调控配体多样性方面的显著优势。在电化学性能测试中,对不同样品在不同电流密度下的放电比容量展开对比。实验结果表明,NDC为有机配体构筑的Ni-MOF(NDC)样品,在0.5Ag-1至5 Ag-1电流密度区间内,其倍率性能优于纯Ni(OH)2样品和Ni-MOF(BDC)样品。值得强调的是,在0.5 A g-1电流密度下,Ni-MOF(NDC)样品放电容量达到1505 F g-1。进一步研究循环稳定性表明,在10 Ag-1的高电流密度下,Ni-MOF(NDC)的循环稳定性显著优于Ni(OH)2和Ni-MOF(BDC)。基于Ni-MOF(NDC)构建的Ni-MOF(NDC)//AC超级电容器,在10 Ag-1电流密度下,初始容量可达500 F g-1,历经300次循环后,容量保持率仍高达约96%。更多还原

【Abstract】 Among various electrochemical energy storage devices,supercapacitors(SC)have attracted much attention due to their excellent stability,efficient energy conversion and storage systems,and hold great application potential in fields such as new energy vehicles,smart grids,uninterruptible power supplies,wearable electronic devices,as well as spacecraft and satellites.The development of energy storage cathode materials with excellent electrochemical performance is a key focus to promote the advancement of supercapacitors.Metal-organic frameworks(MOF),with their ultralarge specific surface area,unique pore structure and abundant active sites,provide a crucial breakthrough for the innovation of electrode materials.Addressing the problems of low actual specific capacity and poor rate performance of nickel-based metal compounds,this thesis adopts multiple strategies to realize the microstructure regulation of nickel-based MOF electrode materials,constructs different two-dimensional nanosheet hybrid structures,so as to develop electrode materials with high specific capacity and excellent rate performance,and further achieve the assembly of high-performance hybrid supercapacitors.The specific research contents include the synthesis and characterization of nickel-based MOF cathode materials for supercapacitors,the optimization of microstructure and electrochemical performance,and the assembly of hybrid supercapacitors.The research contents are as follows:(1)Preparation and electrochemical performance study of NiCoAl-MOF cathode materials.A strategy of alkali etching-induced ion vacancy formation was employed to successfully construct metal-organic framework(MOF)materials with unique structures.Taking advantage of the property that some metals in the material are unstable in strong alkaline electrolytes and thus get removed,vacancies are formed on the material surface to enhance its electrochemical activity and promote electron migration.The solvothermal method was used for in-situ growth of NiCo-MOF and NiCoAl-MOF layered nanosheets on nickel foam substrates,which served as cathode materials for supercapacitors.In the study,the effect of different Ni/Co ratios on the performance of electrode materials was systematically investigated,and the results showed that the Ni7Co3-MOF electrode exhibited the optimal performance,with a specific capacity of 953 F g-1 at a current density of 1 A g-1.On this basis,Al3+ was introduced into the framework structure through an ion doping strategy,enabling it to partially replace the Ni2+and Co2+ metal centers in the skeleton.By utilizing the reaction of aluminum and its hydroxides in strong alkaline electrolytes,alkali etching treatment was applied to selectively remove the aluminum metal centers in the skeleton,thereby forming vacancies.This unique structure significantly improved the discharge specific capacity of the cathode material and optimized the cycle stability.Experimental data showed that the specific capacity of the NiCoAlMOF electrode was greatly increased to 1585 F g-1 at a current density of 1 A g-1.Moreover,at a current density of 10 A g-1,the capacity of NiCoAl-MOF was 400 F g-1 higher than that of NiCoMOF.The initial capacity of the NiCoAl-MOF//AC capacitor at a current density of 10 A g-1 was 1099 F g-1,and after 1000 complete charge-discharge cycles,the capacity retention rate was 98%.(2)Exploration of the Method for Converting Layered Ni(OH)2 to Ni-MOF and Investigation of Its Electrochemical Performance.From the perspective of low cost and high efficiency,this thesis introduces a novel strategy for MOF synthesis.By reacting layered hydroxides with aromatic carboxylic acid organic linkers,a bridge between transition metal hydroxides and MOF was established,leading to the successful preparation of metal hydroxide organic framework materials with unique structures.Using a solvothermal method,layered hydroxide precursors were reacted with two aromatic organic linkers,2,6-naphthalenedicarboxylic acid(NDC)and terephthalic acid(BDC),respectively,resulting in the successful synthesis of two isostructural MOFs.This not only confirms the feasibility of this synthesis method in constructing complex framework structures but also demonstrates its significant advantages in regulating ligand diversity.In electrochemical performance tests,the specific discharge capacities of different samples were compared under various current densities.The results show that the Ni-MOF(NDC)sample,constructed with NDC as the organic ligand,exhibits superior rate performance compared to pure Ni(OH)2 and NiMOF(BDC)samples within the current density range from 0.5 A g-1 to 5 A g-1.Notably,at a current density of 0.5 A g-1,the Ni-MOF(NDC)sample achieves a discharge capacity of 1505 F g-1.Further studies on cycle stability reveal that at a high current density of 10 A g-1,Ni-MOF(NDC)outperforms both Ni(OH)2 and Ni-MOF(BDC).A Ni-MOF(NDC)//AC supercapacitor based on NiMOF(NDC)exhibits an initial capacity of 500 F g-1 at 10 A g-1 and retains approximately 96%of its capacity after 300 cycles.更多还原