导　　师： 金波

学科专业： 080502

授予学位： 硕士

作　　者： ;

机构地区： 吉林大学

摘　　要： 锂离子电池具有高比能量、高电压、长循环寿命以及绿色环保等优势，在便携式电子设备和电动交通工具等领域中得到广泛应用。负极材料是影响锂离子电池性能的关键因素之一。然而，常用的商品化负极材料存在安全隐患和理论容量低等问题，因此开发出性能优良的负极材料具有重要意义。CuxS（CuS、Cu2S）凭借其较高的比容量、价格低廉和环境友好等优点成为具有潜力的负极材料之一，吸引了众多研究学者的目光。 碳纳米管具有优越的导电性和力学性能，将其引入到电极材料中能够形成有效的导电网络，从而改善其循环稳定性。表面包覆是改善材料电化学性能的有效方法，一方面能够为电子及离子的传输提供快速通路，增强导电性能。另一方面能够抑制电极材料粒子间的团聚，提高活性物质的利用率。从制备工艺、成本等因素出发，热解炭包覆比较便于实施，也是目前应用最广泛的包覆方式。本文针对CuS、Cu2S存在的不足之处，通过掺杂碳纳米管和表面包覆等手段对其进行改性研究，分别制备出CuS//MWCNTs复合材料和Cu2S//C复合材料。本论文主要的研究内容与结果如下： （1）首先，采用水热合成法制备出CuS//MWCNTs复合材料。我们通过添加多壁碳纳米管（MWCNTs）来提高CuS的导电性。并研究了MWCNTs含量对CuS//MWCNTs复合材料性能的影响，分别添加了5/%、10/%、15/%（质量比）的MWCNTs。SEM的测试表明，所得到的球状CuS材料是由许多纳米片组成的，球的直径为2-3μm。与其他材料相比，含10/%MWCNTs的复合材料具有较高的放电比容量和循环稳定性。在0.2C的放电倍率下，经过50次循环后，其容量为100.5mAh g-1，而纯相CuS电极的容量仅为64.6mAh g-1。 （2）利用热解葡萄糖法制备出碳包覆Cu2S（Cu2S//C）复合材料，并对其进行电化学性能分析。以葡萄糖为碳源，Cu2S//C复合材料是通过在800oC的氩气氛围下煅烧2h得到的。通过XRD、SEM、TEM、恒流充放电测试以及CV测试对所得复合材料进行表征。通过透射电镜观察到Cu2S颗粒表面包覆着一层均匀的碳层。测试数据表明，相比于纯相Cu2S，Cu2S//C复合材料呈现出优越的循环性能和高放电容量。在100mA g-1的电流密度下，100次循环后，Cu2S//C材料的容量保持在300mAh g-1，远高于容量为30mAh g-1的纯相Cu2S。 Owing to the merits of high energy density, high voltage output, long cycle life andenvironment friendly, lithium ion batteries have been widely used in electronic equipmentsand electric vehicles. Anode materials affect the electrochemical performance of lithium ionbatteries greatly. But the development of commercial anodes has been restrained by the lowtheoretical capacity and safety concerns. It is of great significance to develop anodematerials with excellent performance. Copper sulfides /(CuxS, x=1,2/) have attractedextensive attention due to natural abundance, high theoretical capacity and low cost,however, the poor cycleability limits the practical application as anode materials inlithium-ion batteries /(LIBs/). To solve these problems, CuS//MWCNTs composites andCu2S//C composites were synthesized respectively. Carbon nano tubes /(CNTs/) possess good electrical conductivity and structure stability.CNTs are introduced to active electrode materials to form conductive network, thus theconductivity can be effectively improved. The unique structure contributes to the storage andmove of Li+. Carbon coating is expected to be an effective strategy to improveelectrochemical performance. It is reported that carbon coating can alleviate the volumeexpansion, suppress the aggregation of active particles and increase the electronicconductivity of the electrodes. In this paper, the main research contents and results are asfollows: /(1/) CuS//MWCNTs composites were fabricated through hydrothermal method usingCu/(NO3/)2·3H2O and thiourea as raw materials. The SEM images show that the final productsare sphere morphology consisted of nanoplates. The diameter is around2-3μm. Altering theaddition of MWCNTs to obtain the composites with optimal electrochemical performance,and5/%,10/%,15/%of MWCNTs were chose. The electrochemical tests indicate theCuS//MWCNTs-10/%presents higher discharge capacity and better cycling performance thanpure CuS. The reversible capacity of the Cu2S//MWCNTs-10/%composites is100.5mAh g-1after50circles at0.2C. /(2/) Cu2S//C composites as anode materials for LIBs were synthesized by a hydrothermalmethod and subsequent calcination at800°C for2h, and glucose was used as a carbonsource. The electrochemical performance of Cu2S//C composites was evaluated by cyclic voltammograms and galvanostatic discharge//charge testing. The Cu2S//C composites candeliver a discharge capacity of300mAh g-1after100cycles at a current density of100mAg-1; however, the discharge capacity of pure Cu2S is only30mAh g-1after100cycles.

关 键 词： 硫化铜 碳纳米管 硫化亚铜 碳 锂离子电池 负极材料 循环性能

分 类 号： [TM912]

领　　域： [电气工程]