聚吡咯包覆纳米多元金属化合物阵列的制备及电化学储能研究

发布时间：2018-02-20 19:49

本文关键词： 聚吡咯钼酸钴硫钴镍电极材料超级电容器锂离子电池　出处：《浙江理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：电极材料是决定超级电容器和锂离子电池等新型储能器件性能的关键因素,也是目前储能材料领域的研究热点。在众多电极材料中,过渡金属Ni、Co和Mo的化合物CoMoO_4和NiCo_2S_4材料具有理论比容量高、制备工艺简单、环境友好等优点,吸引了研究者的兴趣。但是,CoMoO_4和NiCo_2S_4本身的电子电导率较低、放电容量和倍率性能不理想;同时在参与电化学可逆反应时材料内部会反复产生较大的应力,长期循环之后材料容易粉化失活脱落。为了改善CoMoO_4和NiCo_2S_4的比容量和循环寿命,本文设计了CoMoO_4和NiCo_2S_4的纳米阵列结构,并将聚吡咯包覆在其表面,利用聚吡咯的高电导率和优异稳定性来改善CoMoO_4和NiCo_2S_4材料的倍率性能、比容量和循环寿命,主要研究内容如下:(1)采用水热法和高温煅烧技术在泡沫镍基底上制备CoMoO_4纳米片自组装柱阵列,然后再利用电化学聚合技术将聚吡咯包覆在CoMoO_4纳米片自组装柱阵列上。通过XRD和FTIR表征聚吡咯包覆CoMoO_4复合材料物相,SEM测试发现复合材料呈现出纳米级厚度的聚吡咯完整一体地包覆在CoMoO_4柱阵列上。将复合材料组装成三电极体系测试它的赝电容性能发现,在电流密度为200 mA g-1的条件下,聚吡咯包覆CoMoO_4复合材料比电容为1195 F g-1,高于未包覆CoMoO_4的1173 F g-1,充放电循环3000次后,聚吡咯包覆CoMoO_4复合材料的比电容(1024 F g-1)仍保持初始值的85.7%,而未包覆CoMoO_4仅剩余52%。聚吡咯包覆CoMoO_4材料表现出更高的比容量,更小的内阻,在充放电过程中的结构更加稳定。(2)采用两步水热法在泡沫镍基底上直接生长NiCo_2S_4纳米管阵列,然后使用电化学聚合技术在NiCo_2S_4纳米管阵列上包覆聚吡咯。通过XRD和FTIR测试分别表征复合材料的物相,SEM和TEM测试揭示了复合材料呈现出8 nm聚吡咯层完整地包覆在NiCo_2S_4纳米管阵列上。将复合材料组装成三电极体系测试它的赝电容性能发现,聚吡咯包覆NiCo_2S_4复合材料的放电比电容与未包覆的相比从1242 F g-1增长到1493 F g-1,增加了20%。在倍率性能测试中,电流密度为24 mA cm-2时,聚吡咯包覆NiCo_2S_4复合材料的平均比电容达到了未包覆的2倍。当电流密度从大电流回归到1 mA cm-2时,聚吡咯包覆NiCo_2S_4的平均比电容达到了初始容量的98%,即1605 F g-1,而未包覆的保持率只有82%。所制备复合材料作为超级电容器电极材料具有较高的比容量,良好的倍率性能和电化学稳定性。(3)本文还研究了聚吡咯包覆CoMoO_4和聚吡咯包覆NiCo_2S_4作为锂离子电池阳极材料的电化学储能性能。在0.2 C电流密度下,聚吡咯包覆CoMoO_4复合材料的比容量达到了1084 mAh g-1,比未包覆的CoMoO_4材料比容量高22%。在0.2 C电流密度下,100个循环后聚吡咯包覆NiCo_2S_4纳米管阵列复合材料比容量保持率为85%,未包覆的NiCo_2S_4材料保持率为65%。聚吡咯的包覆可以提高CoMoO_4和NiCo_2S_4阵列电极材料的电化学储能性能和循环稳定性,这主要是因为高电导率的聚吡咯的包覆提高了复合材料整体的电子电导率,减弱了Li~+脱嵌过程中CoMoO_4和NiCo_2S_4材料结构的破坏和粉化,显示了两种材料复合之后的包覆效应和协同效应。
[Abstract]:The electrode material is decided by super capacitor and lithium ion battery key factors such as new energy storage devices, energy storage is currently the research hotspot in the field of materials. Among the electrode materials, transition metal Ni, Co and Mo compounds CoMoO_4 and NiCo_2S_4 material has high theoretical capacity, simple preparation process, friendly environment. Has attracted the interest of researchers. However, the electronic conductivity of CoMoO_4 and NiCo_2S_4 is low, the discharge capacity and rate performance is not ideal; at the same time to participate in the electrochemical reversible reaction inside the material will repeatedly produced great stress, long cycle after inactivation of powder material is easy to fall off. In order to improve the ratio of NiCo_2S_4 and CoMoO_4 the capacity and cycle life, this paper designs the nano array structure of CoMoO_4 and NiCo_2S_4, and the polypyrrole coated on the surface of modified by polypyrrole with high conductivity and excellent stability The good rate performance CoMoO_4 and NiCo_2S_4 materials, specific capacity and cycle life, the main research contents are as follows: (1) preparation of CoMoO_4 nano self-assembled film pillar arrays on nickel foam substrate by hydrothermal method and calcination technique, then the electrochemical polymerization of polypyrrole coated self-assembly technology column array in CoMoO_4 nanosheets through XRD and FTIR characterization of polypyrrole coated CoMoO_4 composites, SEM test showed that the composite exhibits the nanometer thickness of polypyrrole coated on the CoMoO_4 column to complete one array. The composite materials are assembled into the three electrode system testing pseudocapacitive performance it is found that the current density of 200 mA under the conditions of g-1 polypyrrole coated CoMoO_4 composite material specific capacitance of 1195 F g-1, than the uncoated CoMoO_4 1173 F g-1 after 3000 charge and discharge cycles of polypyrrole coated CoMoO_4 composite material specific capacitance (1024 F g- 1) still maintain the initial value of 85.7%, and not only the remaining 52%. CoMoO_4 coated with polypyrrole coated CoMoO_4 materials exhibit higher specific capacity, smaller internal resistance, the structure in the process of charging and discharging more stable. (2) NiCo_2S_4 nanotube arrays grown directly on nickel foam substrate by two step hydrothermal method, and then use the the electrochemical polymerization of polypyrrole coating technology in NiCo_2S_4 nanotube arrays were characterized. The composite material through XRD and FTIR test, SEM test and TEM reveals that the composite exhibits 8 nm complete polypyrrole layer coated on the NiCo_2S_4 nanotube array. The composite materials are assembled into three electrode system testing pseudocapacitive performance it is found that the polypyrrole coated NiCo_2S_4 composites than uncoated discharge capacitance and compared from 1242 F to 1493 F g-1 growth g-1, 20%. increase in rate performance test, the current density is 24 mA cm-2, The polypyrrole coated NiCo_2S_4 composite average specific capacitance reached 2 times without coating. When the current density return from high current to 1 mA cm-2, the average specific capacitance of polypyrrole coated NiCo_2S_4 reached the initial capacity of 98% F, 1605 g-1, and the retention rate of only uncoated 82%. composites prepared as a super capacitor electrode materials with high specific capacity, rate capability and good electrochemical stability. (3) this paper also studies the polypyrrole coated CoMoO_4 and polypyrrole coated NiCo_2S_4 as electrochemical anode material for lithium ion battery performance. Under the current density of 0.2 C, the polypyrrole coated CoMoO_4 composites than the capacity reached 1084 mAh g-1, than those of uncoated CoMoO_4 material has high specific capacity of 22%. under the current density of 0.2 C, after 100 cycles of polypyrrole coated NiCo_2S_4 nanotube array composite material than the capacity retention rate was 85%, The uncoated NiCo_2S_4 material retention rate of 65%. coated with polypyrrole can improve the electrochemical CoMoO_4 and NiCo_2S_4 array electrode material performance and cycle stability, this is mainly because of the high conductivity of polypyrrole coating improves the electronic conductivity of the composites decreased overall, Li~+ damage and deintercalate powder process CoMoO_4 and NiCo_2S_4 material structure that shows the effect of coated composite material after two and synergies.

【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM53;TM912;TB332

【相似文献】