锂硫电池高比表面中微双孔碳—硫复合正极材料的制备与研究

发布时间：2018-08-26 08:27

【摘要】：目前，，能源短缺和环境污染是人类社会面临的两大难题，研究可持续的清洁能源能够逐渐缓解日益严重的能源和环境危机。锂硫电池作为新一代高能量密度的储能装置受到了广泛关注，这是因为单质硫具有低成本、环境友好和高能量密度等优势。然而，锂硫电池目前仍存在一定的技术瓶颈，主要由于单质硫的不导电性和充放电中间产物在电解液中的易溶性，导致活性材料利用率较低、电池循环寿命较短以及库仑效率较低，严重地制约着锂硫电池的发展。本文主要针对锂硫电池存在的活性材料利用率低以及电池循环性能差两大问题，挑选了一种高比表面中微双级孔碳即活性炭作为正极载体（BET：2200m2g-1）。分别研究了载体材料颗粒大小、比表面积和孔容以及硫-碳复合材料的制备方法对锂硫电池的影响，改进了蒸汽-熔融法制备中微孔材料-硫复合材料。结果表明，高比表面中微双孔碳-硫复合正极材料的最佳制备工艺条件为：较小的活性炭颗粒、较大的比表面积和孔容、蒸汽-熔融法制备中微孔碳-硫复合材料。该工艺条件下制备的Sv-m-E/HACP复合物所制得的锂硫电池在0.5C下的初始放电比容量为920mAh g-1，100圈的容量保持率为90%。本文通过利用碳纤维纸做锂硫电池正极集流体，构建了碳纤维与活性炭颗粒形成的三维导电网状，结合该三维导电网络与上述Sv-m-E/HACP复合物制备的Li-(S/HAC-CPF)电池具有优良的电化学性能。Li-(S/HAC-CPF)电池首圈的放电比容量高达1692mA hg-1，在0.5C、1C、2C、3C、6C下的放电比容量分别是1088mAh g-1、1013mAh g-1、895mAh g-1、829mAh g-1、660mAh g-1，比相同条件下铝片为集流体的锂硫电池相应的放电比容量要分别高出15%、41%、45%、48%、50%。
[Abstract]:At present, energy shortage and environmental pollution are two major problems facing human society. The study of sustainable clean energy can gradually alleviate the increasingly serious energy and environmental crisis. As a new generation of high energy density energy storage devices, lithium sulfur batteries have attracted much attention because of their advantages of low cost, environmental friendliness and high energy density. However, there are still some technical bottlenecks in lithium-sulfur batteries at present, mainly due to the unconductivity of elemental sulfur and the easy solubility of the intermediate products of charge and discharge in the electrolyte, which leads to the low utilization of active materials. The short cycle life and low Coulomb efficiency seriously restrict the development of lithium-sulfur batteries. Aiming at the two problems of low utilization ratio of active materials and poor cycle performance of lithium-sulfur batteries, a kind of micro-double-pore carbon (activated carbon) in high specific surface was selected as positive electrode carrier (BET:2200m2g-1). The effects of particle size, specific surface area, pore volume and the preparation method of sulfur / carbon composites on lithium-sulfur batteries were studied respectively. The results show that the optimum preparation conditions of microporous carbon-sulfur composite cathode material in high specific surface are: smaller activated carbon particle, larger specific surface area and pore volume, and mesoporous carbon-sulfur composite prepared by steam melting method. The initial discharge specific capacity of the lithium-sulfur battery prepared by the Sv-m-E/HACP complex at 0.5 C is 90% for the 920mAh g-1100 cycle. In this paper, a three-dimensional conductive network formed by carbon fiber and activated carbon particles was constructed by using carbon fiber paper as the positive current collector of lithium-sulfur battery. The Li- (S/HAC-CPF) battery prepared by combining the 3D conductive network with the Sv-m-E/HACP complex has excellent electrochemical performance. The discharge specific capacity of the first cycle of Li- (S/HAC-CPF) battery is as high as that of 1692mA hg-1, at 0.5CU 1CU 2CU 3C 3C, respectively, which is 1088mAh g-1n 1013mAh g-1895mAh g-1829mAh g-1660mAh g-1, which is higher than that under the same conditions. The specific discharge capacity of the lithium-sulfur battery with aluminum as a fluid collector should be 15% higher than that of 41% and 45% 48.50% higher than the corresponding discharge capacity.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912;TB332

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