【作者】 谢建军；

【导师】 刘黎；

【作者基本信息】 湘潭大学 ， 化学工程， 2018， 硕士

【摘要】 近年来,锂/钠离子电池正极材料的研究已取得了丰硕的成果。因此,一些研究人员转而探讨未来潜在和适用的锂/钠离子电池负极材料。在许多适用于锂/钠离子电池的负极材料中,锑基负极材料由于其较高的理论比容量和优异的储锂/钠性能,引起了人们大量的关注和研究。然而,材料本身存在的首次库伦效率低、倍率性能差、循环稳定性差等缺点一直是研究人员关注的重点。本论文从制备方法、工艺条件的影响、结构特点及电化学性能几个方面对锑基负极材料进行了系统的研究。论文的具体研究内容如下:1.利用水热法制备了亚微米棒状氯氧化锑负极材料。该负极材料同时具有单斜晶系的Sb405Cl2相和Sb8O11Cl2相,以及少量正交晶系的Sb2S3相。主相Sb4O5Cl2和Sb8O11Cl2的晶体结构都是层状结构,这种层状结构有利于Li+/Na+扩散。通过研究证明,该氯氧化锑负极材料具有稳定的循环性能。在电压范围为0.01-2.0 V(vs.Li/Li+),制备的亚微米棒状氯氧化锑负极材料在电流密度为50 mA g-1时的首次放电比容量为1355.6 mAh g-1,循环50次后的放电比容量高达694 mAh g-1,循环100次后的放电比容量仍有401 mAh g-1;同时,在电压范围为0.01-2.0 V(vs.Na/Na+),电流密度为50 mA g-1时,该氯氧化锑负极材料循环50次后的放电比容量为452 mAh g-1。2.通过无模板法制备了空心微球结构的Sb2S3负极材料,只使用L-半胱氨酸和SbCl3作为原料而不添加任何表面活性剂。正如预期的那样,空心微球Sb2S3表现出优异的储锂/钠性能和出色的倍率性能。在电压范围为0.01-2.0 V(vs.Li/Li+),电流密度为200mAg-1时,该空心微球Sb2S3循环50次后的放电比容量为674 mAh g-1。同时,在电压范围为0.01-2.0 V(vs.Na/Na+),电流密度为200 mA g-1时,该空心微球Sb2S3负极材料循环50次后的放电比容量为384 mAh g-1。显着的储锂/钠性能可归因于其纳米尺寸和三维分层结构的协同效应;优异的稳定性能可归因于空心微球内部足够的空隙空间,在反复的充放电过程中可缓冲体积膨胀。3.利用静电纺丝技术设计并制备出了直径均一、多孔的Sb2S3/C复合材料。研究结果表明,Sb2S3/C复合材料作为钠离子电池负极材料具有较好的循环稳定性,归因于纳米纤维中的多孔结构可以增加电极与电解液之间的接触面积,同时为Na+的存储提供更多的空位。在电压范围为0.01-2.0V(vs.Na/Na+),电流密度为50 mA g-1时,制备的Sb2S3/C复合材料首次放/充电比容量为816/432 mAh g-1;在电流密度500 mA g-1循环100次后,放电比容量为289 mAh g-1,库伦效率一直稳定在99%左右。可以观察到,材料的容量衰减主要发生在前10圈,随后具有很好的循环性能,Sb2S3/C复合材料的比容量和倍率性能有待进一步改善。更多还原

【Abstract】 In recent years,there have been successful studies into the development of cathode materials for lithium/sodium-ion batteries.Therefore,many researchers have focused on exploring potential suitable anode materials for future lithium/sodium-ion batteries.Among the many suitable anode materials for lithium/sodium-ion batteries,antimony-based anode materials have received significant attention owing to its high theoretical specific capacity and superior lithium/sodium-storage performance.Nevertheless,the drawbacks of their low initial coulombic efficiency,poor rate capability and cyclic durability problems have always been the focus of the researchers,which also limit the practical uses of these anodes.This dissertation particularly investigated the preparation methods,structural characters,technological conditions and the electrochemical performance of the antimony-based anode materials.And the main works are as follows:1.Antimony oxychlorides submicro rods anode materials have been successfully synthesized by a simple and facile hydrothermal reaction.This anode material contained the monoclinic Sb4O5Cl2 phase,Sb8O11Cl2 phase and the orthorhombic Sb2S3 phase.The crystal structure of main phase Sb4O5Cl2 and Sb8O11Cl2 are layered structures,this structure is probably beneficial for the diffusion of Li+/Na+.The research results proved that the antimony oxychlorides anode material exhibits a prominent cycle performance.It can deliver a high initial discharge capacity of 1355.6 mAh g-1 at a current density of 50 mA g-1 in the voltage range of 0.01-2.0 V(vs.Li/Li+).After 50 cycles,the discharge specific capacity is as high as 694 mAh g-1,and the discharge specific capacity remains 401 mAh g-1 after 100 cycles.What’s more,antimony oxychlorides material also exhibits brilliant cycle property in sodium-ion batteries at a current density of 50 mA g-1 in the voltage range of 0.01-2.0 V(vs.Na/Na+),which has a high discharge capacity of 452 mAh g-1 after 50 cycles at a current density of 50 mA g-1.2.Hierarchical Sb2S3 hollow microspheres have been effectively synthesized through a template-free method employing L-cysteine and SbCl3 as raw materials without adding any surfactants.As expected,the Sb2S3 hollow microspheres exhibit superior lithium/sodium-storage capacity and outstanding rate property.The prepared Sb2S3 hollow microsphere anode material can deliver a discharge capacity of 674 mAh g-1 after 50 cycles at a current density of 200 mA g-1 in the voltage range of 0.01-2.0 V(vs.Li/Li+).Sb2S3 hollow microspheres also display a prominent sodium-storage capacity and maintain a reversible discharge capacity of 384 mAh g-1 after 50 cycles at a current density of 200 mA g-1 in the voltage range of 0.01-2.0 V(vs.Na/Na+).The remarkable lithium/sodium-storage property may be attributed to the synergetic effect of its nanometer size and three-dimensional hierarchical architecture,and the outstanding stability property is attributed to the sufficient interior void space of hollow microspheres,which can buffer the volume expansion.3.The porous Sb2S3/C composite with uniform size and superior dispersity are designed and prepared by the electrospinning technique.The results showed that Sb2S3/C composite has excellent cycle stability as the anode material of sodium-ion batteries.The porous structure of the nanofibers can increase the contact area between the electrolyte and electrode,and provide extra active sites for the Na+ storage.The first discharge/charge capacity of Sb2S3/C composite is 816/432 mAh g-1,at a current density of 50 mA g-1 in the voltage range of 0.01-2.0 V(vs.Na/Na+).However,at a current density of 500 mA g-1,the discharge specific capacity remains 289 mAh g-1 after 100 cycles,and the coulomb efficiency has been stable at around 99%.It can be observed that the capacity decay of the material occurs mainly in the first 10 cycles,followed by a good cycle performance.The specific capacity and rate performance of the Sb2S3/C composite material need to be further improved.更多还原