基于石墨烯的锂硫电池改性研究

发布时间：2018-04-19 04:07

本文选题：锂硫电池 + 石墨烯　；参考：《电子科技大学》2015年硕士论文

【摘要】：锂硫电池因具有极高的理论能量密度,且硫价格低廉、储备丰富、环境友好等优点,受到广泛关注,被认为是最具潜力的储能体系之一。但是,硫及其放电终产物导电性差,反应中间产物易溶于有机电解液,以及充放电过程会导致巨大的体积变化,这些缺点使得锂硫电池实际容量较低,循环稳定性较差。锂硫电池的改性,已成为当前储能领域的研究前沿。针对以上问题,本论文系统研究了锂硫电池硫正极材料的石墨烯包覆改性,锂硫电池隔膜的复合改性,以及无常规集流体的新构型锂硫电池电极的电化学性能。主要研究内容与结果如下:(1)研究了肼与二苄基二硫还原氧化石墨烯(rGO)对硫正极材料的包覆改性。研究结果表明,二苄基二硫还原rGO包覆改性具有更好的电化学性能:肼还原的rGO与S复合的正极材料在0.2 C下,初始容量为443 mAh/g,100次循环后容量保持299 mAh/g,衰减率为0.325%/循环;二苄基二硫还原的r GO与S复合的正极材料在0.2 C下初始容量为628 mAh/g,100次循环后容量保持400 mAh/g,衰减率为0.36%/循环。(2)研究了绝缘性氧化物涂层及高导电涂层对锂硫电池隔膜的改性。研究结果表明,采用高导电的石墨烯改性隔膜的锂硫电池具有最优异的电化学性能:采用GO改性隔膜的锂硫电池,在0.2 C下,初始放电容量为368 mAh/g,100次循环后容量为305 mAh/g,衰减率为0.17%/循环;用TiO2改性隔膜的锂硫电池,在0.2 C下,初始放电容量为510 mAh/g,100次循环后容量为385 mAh/g,衰减率为0.245%/循环;用导电石墨粉末改性隔膜的锂硫电池在0.2 C下初始容量高达1148 mAh/g,100次循环后容量保持694 mAh/g,衰减率为0.395%/循环;rGO改性隔膜的锂硫电池,在0.2C下,初始容量为1067 mAh/g,100次循环后容量为878 mAh/g,衰减率为0.18%/循环。(3)研究了无常规集流体的新构型锂硫电池电极的电化学性能。研究结果表明,CNT-S/隔膜构型的电极具有最优异的电化学性能:rGO-S/隔膜构型的电极在0.2 C下,初始容量为799 mAh/g,100次循环后容量为535 mAh/g,衰减率为0.33%/循环;Super P-S/隔膜构型的电极在0.2 C下,初始容量为618 mAh/g,100次循环的容量为363 mAh/g,衰减率为0.41%/循环;CNT-S/隔膜构型的电极在0.2 C下,初始容量为815 mAh/g,100次循环后容量为650 mAh/g,容量衰减率为0.20%/循环。
[Abstract]:Lithium-sulfur batteries have attracted wide attention due to their high theoretical energy density, low sulfur price, abundant storage and environmental friendliness, and are considered as one of the most potential energy storage systems.However, the conductivity of sulfur and its discharge end product is poor, the intermediate product is easily dissolved in organic electrolyte, and the charge-discharge process will lead to huge volume change. These shortcomings make the actual capacity of lithium sulfur battery low and the cycle stability is poor.The modification of lithium-sulfur batteries has become the research frontier in the field of energy storage.In order to solve the above problems, the paper systematically studied the modification of graphene coating, the composite modification of the membrane of lithium-sulfur battery, and the electrochemical performance of non-conventional lithium-sulfur battery electrode.The main research contents and results are as follows: (1) the coating modification of sulfide-cathode materials by hydrazine and dibenzyl disulfide reductive graphene oxide rGO) was studied.The results show that the coating modification of dibenzyl disulfide reduction rGO has better electrochemical performance: at 0.2C, the initial capacity of hydrazine-reduced rGO / S composite cathode material is 443 mg / g and the initial capacity is 299mAh/ g after 100 cycles, and the attenuation rate is 0.325g / cycle.The modification of insulating oxide coating and highly conductive coating on lithium-sulfur battery was studied by using dibenzyl disulfide composite cathode material with initial capacity of 628 mg 路g / g at 0.2 C and capacity of 400 mg / g after 100 cycles, and the attenuation rate was 0.36% / cycle.The results show that the lithium-sulfur battery modified by graphene with high conductivity has the best electrochemical performance.The initial discharge capacity is 368mAh/ g after 100 cycles, the attenuation rate is 0.17 / cycle, the initial discharge capacity is 510mAh/ g / g at 0.2C, the initial discharge capacity is 510mAh/ g / g after 100 cycles, the attenuation rate is 0.245 / cycle, and the initial discharge capacity is 305mAh路 g / g after 100 cycles, and the attenuation rate is 0.245a / cycle, and the initial discharge capacity is 510mAh/ g / g at 0.2C.The initial capacity of the lithium-sulfur cell modified with conductive graphite powder was up to 1148 mg 路g ~ (-1) 路g ~ (-1) after 100 cycles at 0.2C, and the attenuation rate was 0.395g / cycle / RGO-modified lithium-sulfur cell. At 0.2C, the initial capacity of the lithium-sulfur cell was 1148 mAh-g ~ (-1).The initial capacity is 1067 mg / g and the capacity is 878 mg / g, and the attenuation rate is 0.18% / cycle. 3) the electrochemical performance of the new configuration lithium sulfur cell electrode without conventional collector is studied.The results show that the electrode with CNT-S / diaphragm configuration has the most excellent electrochemical performance. The initial capacity of the electrode with the structure of RGO-S / membrane is 0.2C, the initial capacity of the electrode is 799mAh-g / g after 100 cycles, the capacity of the electrode is 535mAh/ g after 100 cycles, and the attenuation rate is 0.33g / cycle P-S/ membrane configuration at 0.2C.The initial capacity is 618 mAh/ g / 100 cycle capacity is 363 mg / g, the attenuation rate is 0.41 / cycle CNT-S / diaphragm configuration electrode at 0.2 C, the initial capacity is 815 mAh/ g ~ (-1) 100 cycle capacity is 650 mAh-g / g, and the capacity attenuation rate is 0.20 / cycle.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM912

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