电纺丝制备纳米纤维无纺布及其在锂硫电池中的应用

发布时间：2018-05-03 00:23

  本文选题：锂硫电池 + C纳米纤维无纺布　； 参考：《江苏大学》2017年硕士论文

【摘要】：由于能源消耗带来的环境问题,人们对高能量电池需求日渐增加。锂硫电池因其能量密度高(2600 Wh kg~(-1))成为研究热潮。但其自身不足减缓了锂硫电池的商业化进程,比如硫和最终放电产物的低电导性、循环过程中正极的体积膨胀效应以及长链多硫化物的“穿梭效应”,这些都造成了硫正极活性物质的损耗。活性物质低利用率影响其电化学性能,制约电池实际应用化进程。针对上述存在问题,本学位论文主要开展了电池新型结构设计-插层改性研究。拟以高负载导电炭黑BP2000/硫(W_t=70%)复合电极为研究对象,通过一步静电纺丝法制备碳(C)纳米纤维、氧化铝/碳(Al_2O_3/C)复合纳米纤维和镍/碳(Ni/C)复合纳米纤维无纺布,并探究了不同煅烧温度和铝(Al)盐、镍(Ni)盐添加量制备的复合纳米纤维无纺布在锂硫电池中的应用及对其电化学性能的影响。主要研究结果具体如下:采用简便的一步静电纺丝法制备了C纳米纤维无纺布,同时探究不同煅烧温度对其作为功能性插层应用在电池中及对其电化学性能的影响。C纳米纤维无纺布功能性插层改性的锂硫电池在容量利用率、可逆性和循环倍率性能方面皆表现出了优异的性能。在1C倍率下不同煅烧温度的C纳米纤维无纺布插层改性电池,循环200圈后放电比容量都仍然保持在760 mAh g~(-1)以上,明显优于不加插层的锂硫电池(在0.5C倍率下循环200圈,仅有260 mAh g~(-1))。电性能的提高得益于C纳米纤维无纺布功能性插层提供的良好的三维导电网络结构,在充放电过程中减少了多硫化物的迁移穿梭现象。采用一步静电纺丝法制备了不同煅烧温度和Al盐添加量的Al_2O_3/C复合纳米纤维无纺布,并研究其作为功能性插层对锂硫电池电化学性能的影响。研究结果表明,Al盐添加量为1g的复合纳米纤维无纺布插层改性电池在900℃时表现出较好的循环性能,在1 C倍率下初始放电容量为1360 mAh g~(-1),循环200圈仍有近1000 mAh g~(-1)的放电比容量,且优于同温度下的C纳米纤维无纺布插层改性(1C倍率下循环200圈放电比容量在760 mAh g~(-1));且倍率性能亦明显优于C纳米纤维无纺布插层改性。研究结果表明Al_2O_3/C复合纳米纤维中的极性金属-氧键可有效抑制多硫化物的穿梭。采用静电纺丝法制备了Ni/C复合纳米纤维无纺布。研究了不同煅烧温度和Ni盐添加量对锂硫电池电化学性能的影响。研究发现Ni盐添加量为1g的复合纳米纤维在900℃时表现出优异的循环性能。在1 C倍率下初始放电容量为1062mAh g~(-1),循环200圈后保持910 mAh g~(-1)的稳定放电比容量。即使在2 C倍率下,仍然保持695 mAh g~(-1)的放电比容量。研究结果表明Ni/C复合纳米纤维无纺布可作为新的二次集流体,为活性物质提供良好的电子传输通道,从而改善锂硫电池的循环和倍率性能。同时其多孔网络结构能够抑制多硫化物的扩散。
[Abstract]:Due to the environmental problems caused by energy consumption, the demand for high energy batteries is increasing day by day. Lithium-sulfur battery has become a hot research subject because of its high energy density of 2600 Wh / kg ~ (-1). However, its shortcomings have slowed the commercialization of lithium-sulfur batteries, such as the low conductivity of sulfur and final discharge products, the volumetric expansion of positive electrodes during cycling and the "shuttle effect" of long-chain polysulfide. These results in the loss of sulfur positive active substances. The low utilization rate of active substances affects their electrochemical performance and restricts the practical application of batteries. In order to solve the above problems, this dissertation focuses on the design of new battery structure-intercalation modification. In this paper, the composite electrode of high load conductive carbon black BP2000/ T / W / T 70) was used as the research object. The carbon fiber was prepared by one step electrostatic spinning method. The composite nanofibers of alumina / carbon Al _ 2O _ 3 / C _ 2O _ 3 / Ni / C / Ni / C / C composite nanofibers were prepared. The application of composite nanofiber nonwoven fabric with different calcination temperature, Al _ 2O _ 3 and Ni _ (2) salt in lithium sulfur battery and its effect on electrochemical performance were investigated. The main results are as follows: C nanofiber non-woven fabric was prepared by a simple one-step electrostatic spinning method. At the same time, the effect of different calcination temperature on the application of functional intercalation in the battery and on its electrochemical performance. The capacity utilization of the functional intercalated lithium sulfur battery modified by functional intercalation of carbon nanofiber nonwoven fabric was investigated. Both the reversibility and the cyclic rate performance show excellent performance. The discharge specific capacity of C nanofiber non-woven intercalated modified battery with different calcination temperature at 1C ratio is still above 760 mAh / g / 1 after cycle 200th cycle, which is obviously superior to that of lithium sulfur cell without intercalation (circulating 200 cycles at 0.5C ratio). Only 260 mAh. The improvement of electrical properties is due to the good three-dimensional conductive network structure provided by the functional intercalation of C nanofiber nonwoven fabric, which reduces the migration and shuttle phenomenon of polysulfide during charging and discharging. The non-woven Al_2O_3/C composite nanofibers with different calcination temperature and Al salt content were prepared by one-step electrostatic spinning method. The effect of the functional intercalation on the electrochemical performance of lithium sulfur battery was studied. The results show that the composite nano-fiber non-woven intercalation modified battery with 1 g Al salt has good cycling performance at 900 鈩，

本文编号：1836120