【作者】 朱嫦娥；

【导师】 王立新；

【作者基本信息】 河北工业大学 ， 材料学， 2005， 硕士

【摘要】 聚吡咯（PPy）、聚苯胺（PAn）具有良好的导电性和电化学氧化还原特性,而且电荷贮存能力强,在空气和水中稳定性较好,因而可作为二次电池的正极活性材料。本文采用吸附聚合工艺化学氧化法,将PPy（PAn）与SiO₂、C等无机纳米粒子复合制备出导电复合材料,以此为正极制备出性能较好的Li/PPy（PAn）二次电池。 对于聚吡咯基复合材料体系,首先优化了PPy/SiO₂、PPy/C复合材料的制备条件,研究了反应温度、反应时间、掺杂剂种类和数量、偶联剂用量、二氧化硅和炭黑用量对复合材料电导率的影响。通过XPS、TEM、SEM、TGA和四探针分析表明:经偶联剂MPS处理后SiO₂纳米粒子的分散性明显改善,与吡咯聚合后,得到的粒子为表面富含PPy的PPy/MPS—SiO₂复合材料,且比PPy/SiO₂复合材料包覆的完全,外型似“木莓形貌”,复合材料中PPy的含量增加,电导率升高,由未处理时的19.23S/cm增至处理后的31.25S/cm。同样,炭黑吸附聚合制备的PPy/C复合材料显示出较好的粒度和较高电导率。同纯PPy（PAn）相比,材料的致密性和聚合物粒界间的作用力明显提高,复合材料显示出较高的电导率和堆积密度、较好的粒度,适宜正极膜的制作。以上述方法制备的聚吡咯基复合材料作正极,金属锂箔作负极,1mol/l LiPF₆/EC+DMC+EMC（1∶1∶1）作电解质组装了扣式锂二次电池,通过元素分析、SEM研究了电池的充放电反应,通过循环伏安测试、电池综合性能测试仪研究了电池的性能。聚吡咯基复合材料作正极是通过掺杂与脱掺杂来实现充电与放电的,充放电电流以小于1mA为宜,充放电电压控制在3.8～2.0V之间,聚合物比较稳定,基本上没有副反应,最高放电容量可达85.02mAh/g;电极反应可逆性好,循环性能理想,充放电循环30次后,容量下降了6.8%,而库仑效率仍达98%以上,是一种比较理想的锂二次电池正极活性材料。同时研究表明:复合组分、复合材料的电导率、正极片的堆积密度对电池性能有着明显的影响;在保证绝缘性和机械强度的情况下,隔膜应越薄越好;集电极铝箔优于铝网。 对于聚苯胺基复合材料体系,研究了氧化剂种类、盐酸用量、炭黑用量对复合材料电导率的影响;以化学法制备的聚苯胺基复合材料作正极组装了Li/PAn二次扣式电池,探讨了氧化剂种类、聚合工艺、导电剂的加入方式以及PAn与金属氧化物复合后作电池正极的性能。结果表明聚苯胺基复合材料作锂二次电池正极的性能虽不如聚吡咯基复合材料,但综合考虑其仍不失为一种比较理想的锂二次电池正极活性材料。更多还原

【Abstract】 Polypyrrole（PPy） and polyaniline（PAn） can be used as cathode electroactive materials in secondary battery because they possess good conductivity and electrochemical redox property, high electric charge reserve ability and good stability in air or water. In this paper, polymer/inorganic nanoparticles conducting composites such as polypyrrole/silica （PPy/SiO₂）, polypyrrole/carbon black （PPy/C）, polyaniline/carbon black（PAn/C） were prepared by adsorption chemical polymerization. As a result, compactness and particles interaction force were improved. Composites showed higher conductivity and bulk density, better granularity and adapt more to make cathode film than PPy. Accordingly, Li/PPy secondary battery showed good properties.For PPy-based composites, preparation conditions were optimized firstly. The influences of reaction temperature, reaction time, the kinds and amount of doping agent , the amount of coupling agent and inorganic nanoparticles（SiO₂, C） on the conductivity were investigated. Through analysis by XPS, TEM, SEM, TGA and four-probe messurement, it was indicated that the distribution of SiO₂ nanoparticles was meliorated after modified by coupling agent MPS, and thereby the resulted PPy/MPS-SiO₂ composites which showed "raspberry" shape exhibited PPy-rich surface compared to PPy/SiO₂, and they have higher PPy content and resulted in higher conductivity increased from 19.23 S/cm to 31.25 S/cm. Also, PPy/C composites synthesized by carbon black adsorption polymerization showed more moderate particle size, morphology and higher conductivity. At the same time, the bulk density and film molding property were also improved. Button-type lithium secondary batteries were assembled with PPy-based composites synthesized above as cathode, lithium film as anode and lmol/1 LiPF₆/EC+DMC+EMC（l:l:l） as electrolyte. In order to study the properties of these batteries, electrochemical techniques, elemental analysis and SEM measurements were applied. It was found that PPy-based composites used as cathode were through doping and de-doping to realize charge and discharge. They showed relative stability and no side-reaction occurred accompanying when batteries were cycled between 2V and 3.8V at less than 1mA electric current. The most discharge capacity is 85.02mAh/g. The cyclability is good with which the reversibility of the cathode reaction was possible since the capacity decreased no more than 6.8% and coulombic efficiency was yet over98% after 30 cycles. In sum, PPy-based composites were perfect electroactive materials used as cathode in lithium secondary battery. It was also indicated that component and conductivity of these composite and cathode film’ s bulk density had distinctly influence on the properties of these batteries. The thiner of separators, the better properties of these batteries when they ensured insulation and mechanical intensity. Aluminum foil was better than aluminum net when used as collector.As for PAn-based composites, the influences of the kinds of oxidant, the amount of hydrochloric acid and barbon black on conductivity were investigated, Li/PAn button-type secondary batteries were assembled with PAn-based composites which were synthesized by chemical oxidative polymerization and used as cathode, the influences of the kinds of oxidant, synthesized technics, conducting carbon black added mode and PAn/metal oxide composites used as cathode on the properties of these batteries were studied. It was indicated that PAn-based composites used as electrode materials in lithium secondary battery were inferior to PPy-based composites, but they were also perfect electroactive materials considered all-around.更多还原