聚合物多孔炭的制备及锂硫电池性能研究

发布时间：2018-11-10 11:01

【摘要】：经过20多年的发展,传统的脱/嵌型锂离子电池在能量密度方面,几乎已经达到了它的理论极限值,但是仍然不能满足高速发展的电子工业和新兴的电动汽车等行业的要求,寻找具有更高能量密度的电池系统迫在眉睫。锂硫电池其理论能量密度高达2600 Wh·kg-1,且成本低廉、环境友好。有望成为替代锂离子电池的新一代二次电池。但是锂硫电池存在单质硫的绝缘性、充放电过程中体积膨胀、容量衰减等问题,这些关键问题严重阻碍了锂硫电池的实用化。围绕硫电极存在的关键问题.本论文以发展高性能硫正极为目的,制备出了具有特殊纳米结构的多孔炭材料作为硫的载体,得到炭-硫复合正极材料,改善锂硫电池的性能。主要研究内容和结果如下:1.通过简单的方法制备出具有大比表面积和丰富贯通孔道的聚合物多孔炭(PPC500)。负载硫之后得到含硫量为75 wt%的复合正极材料SPPC500,单质硫在SPPC500体系中分散均匀。但化学测试结果表明SPPC500正极具有良好的倍率性能和循环稳定性。在0.2C倍率下,首次放电比容量高达1397.3 mAhg-1,达到理论容量的83.4%。在0.5C下循环超过1000圈,平均衰减率为0.074%。2.采用简单地聚合反应的方法制备了氮原子杂化的聚合物多孔炭(NPPC),随后通过熔融扩散的方法得到复合材料SNPPC。合适的氮含量(4.06 wt%)能够有效地改善载体材料的导电性,同时氮原子的存在可以增强聚合物多孔炭表面对聚硫离子的吸附作用,从而有效抑制多硫化的溶解扩散。含硫量为72 wt%的SNPPC,在0.5C下循环超过600圈,每圈平均衰减率仅为0.06%;倍率测试表明,即使在2C倍率下,放电比容量仍然保持有547.9 mAh·g-1,当返回到0.1C时,放电比容量回到732.0mAh·g-1。这表明SNPPC具有良好的循环性能和倍率性能。
[Abstract]:After more than 20 years of development, the energy density of the traditional desorption / embedded lithium ion batteries has almost reached its theoretical limit, but it still can not meet the requirements of the high-speed development of the electronics industry and the emerging electric vehicle industry. It is urgent to find a battery system with higher energy density. The theoretical energy density of lithium-sulfur battery is as high as 2600 Wh kg-1, low cost and environmentally friendly. It is expected to be a new generation of secondary battery instead of lithium ion battery. However, there are some problems in lithium sulfur battery, such as the insulation of simple sulfur, volume expansion and capacity attenuation during charge and discharge, which seriously hinder the application of lithium sulfur battery. The key problems around sulfur electrode. In order to develop the high performance sulfur positive electrode, the porous carbon material with special nanostructure was prepared as the carrier of sulfur in this paper, and the carbon sulfur composite cathode material was obtained to improve the performance of lithium sulfur battery. The main contents and results are as follows: 1. Polymer porous carbon (PPC500) with large specific surface area and abundant perforated channels was prepared by a simple method. After the sulfur was loaded, the compound cathode material, SPPC500, with sulfur content of 75 wt%, was dispersed uniformly in the SPPC500 system. But the chemical test results show that the SPPC500 positive electrode has good rate performance and cycle stability. At the rate of 0.2C, the first discharge specific capacity is up to 1397.3 mAhg-1, and reaches 83.4% of the theoretical capacity. The average attenuation rate is 0.074. 2 at 0.5 C when the cycle is over 1000 laps. The nitrogen atom hybrid polymer porous carbon (NPPC),) was prepared by a simple polymerization method, and then the composite SNPPC. was obtained by melt diffusion method. The proper nitrogen content (4.06 wt%) can effectively improve the conductivity of the carrier material, and the presence of nitrogen atom can enhance the adsorption of polysulfide ions on the porous carbon surface of the polymer, thus effectively inhibit the solubilization and diffusion of polysulfide. The SNPPC, with 72 wt% sulfur content circulates more than 600 cycles at 0.5C, and the average attenuation rate per cycle is only 0.06. The specific discharge capacity is still 547.9 mAh g-1 even at 2C rate, and when returned to 0.1C, the discharge specific capacity returns to 732.0mAh g-1. This shows that SNPPC has good cycling performance and rate performance.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM912

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