【作者】 林春；

【导师】 黄志高；

【作者基本信息】 福建师范大学 ， 凝聚态物理， 2022， 硕士

【摘要】 目前,锂离子电池已经在便捷式储能设备、新能源汽车、电网储能等领域得到广泛应用,但是锂资源短缺、安全性等问题,阻碍了锂离子电池的进一步发展。水系锌离子电池由于自然资源丰富、安全性高等优点,被认为是锂电池的替代产品,能广泛应用于大规模电网储能。锌离子具有比锂离子更高的电荷,离子脱嵌比较困难,因此可以利用的正极材料较少。目前锌离子电池电极材料还面临着两大主要问题:第一是,电极材料主要局限于锰/钒基材料、普鲁士蓝类似物等,但是这些电极材料都受一些因素影响,限制了锌离子电池的发展;第二是,关于锰/钒基等材料的电化学储能机制还未解释清楚,存在争议。锌离子电池发展的关键是寻找到适配的新型锌离子电极材料,并且探究清楚内部储能机理。本文围绕锌离子电池电极材料开展研究,从不同种类的材料的合成及改性出发,了解材料的电化学性能,探究材料的储锌机理。具体研究内容如下:第一部分,采用湿法化学转化法从废旧铅酸电池废料中回收合成PbO,将PbO作为水系锌离子电池电极材料。研究结果表明,所设计的Zn/PbO电化学体系,在0.1A/g的电流密度下,具有136m Ah/g的比容量。通过对该体系的储能机理的探究,发现PbO能自发形成碱式硫酸锌（ZHS）纳米片作为固体界面层（SEI）钝化层,防止活性材料的脱溶。在碱式硫酸锌的辅助下,Pb SO₄和Pb之间发生了可逆相变。协同两相反应机制在充放电时产生超平坦的电压平台。第二部分,通过水热反应制备了不同石墨烯含量的Bi₂S₃/RGO复合材料,将其用于水系锌离子电池正极材料。研究结果表明,相对于Bi₂S₃、Bi₂S₃-RGO30、Bi₂S₃-RGO10,Bi₂S₃-RGO20的样品具有最佳的电化学性能,在0.1A/g的电流密度下,其首次放电容量高达313.2m Ah/g,而Bi₂S₃仅有209.4 m Ah/g,复合材料的赝电容贡献比例较多,电化学性能有了明显的提高。通过非原位的XRD、XPS对Bi₂S₃/RGO复合材料电化学机理进行探究,实验表明,Bi₂S₃/RGO复合材料为锌离子提供扩散的通道,使锌离子在充放电时能够可逆地脱嵌,同时伴随着碱式硫酸锌的可逆反应。更多还原

【Abstract】 Nowadays,lithium ion batteries（LIBs）have been widely used in convenient energy storage equipment,new energy vehicles,power grid energy storage and other fields,but the shortage of lithium resources,safety and other problems,hinder the further development of LIBs.Because of the advantages of abundant natural resources and high safety,aqueous Zinc ion batteries（ZIBs）are considered as an alternative to LIBs and can be widely used in large-scale power grid energy storage.Zinc ions have a higher charge density than lithium ions,and the ions are more difficult to be intercalated/extracted from the crystal lattice of cathode materials,which makes the available cathode material very limit.ZIBs are currently facing two major problems:first,electrode materials are mainly limited to manganese/vanadium based materials,Prussian blue analogue,and so on,but these electrode materials are affected by some factors,restricting the further development of ZIBs;Second,the electrochemical energy storage mechanism of manganese/vanadium based materials has not been clearly explored,and remain elusive.The key to the development of ZIBs is to find suitable new zinc ion electrode materials and explore the charge storage mechanism.This paper focuses on the study of zinc ion battery electrode materials,starting from the synthesis and modification of different kinds of materials,to understand the electrochemical properties of materials,explore the zinc storage mechanism of the synthesized materials.The research contents are as follows:In the first part,PbO was synthesized from waste lead-acid battery by wet chemical conversion method,and PbO was used as the electrode material of zinc ion battery.The materials and electrodes were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）and electrochemical characterization methods.Electrochemical tests show that the designed Zn/PbO electrochemical system has a specific capacity of 136m Ah/g at the current density of 0.1A/g.By systematically exploring the energy storage mechanism of the system,it is found that（ZnSO₄）[Zn（OH）₂]₃·5H₂O（ZHS）nanosheets can spontaneously from on the PbO surface as solid interface layer（SEI）passivation layer to prevent the dissolution of active materials.With the help of ZHS,the reversible phase transition occurs between Pb SO₄ and Pb.The synergetic two-phase reaction mechanism produces an ultra-flat voltage platform during charging and discharging.In the second part,bismuth sulfide（Bi₂S₃）and reduced graphene oxide（RGO）composites with different graphene contents were prepared by hydrothermal reaction,which were used as cathode materials for ZIBs.XRD,Raman,SEM and XPS characterizations show that the prepared Bi₂S₃nanoparticles successfully incorporates with RGO.Compared with bare Bi₂S₃ and the mixed components,Bi₂S₃-RGO20,the Bi₂S₃ mixed with 20 mg of RGO（～10 wt.%）has the best electrochemical performance.At the current density of 0.1A/g,the initial discharge capacity of Bi₂S₃-RGO20 is as high as 313.2m Ah/g,while the bare Bi₂S₃ only delivered 209.4m Ah/g.Besides,the pseudocapacitive effect in Bi₂S₃-RGO20 is greater than the other samples,and the electrochemical performance is significantly improved.Furthermore,the electrochemical charge storage of Bi₂S₃/RGO composite was explored by ex-situ XRD and XPS.The experiment show that Bi₂S₃/RGO composite provides abundance diffusion channel for zinc ions,enabling zinc ions to be reversibly inserted/extracted during charge and discharge,accompanied by the reversible formation and dissolution of ZHS.更多还原