摘要
本研究以苯胺为单体,过硫酸铵为氧化剂,植酸为掺杂酸,与木质素磺酸盐进行化学聚合,通过原位化学氧化法合成了电子传导能力良好和电容性能优异的木质素磺酸盐/聚苯胺(LS/PANI)电极材料,采用场发射扫描电子显微镜(FESEM)、傅里叶变换红外光谱仪(FT-IR)和比表面积及孔径分析仪(BET)对LS/PANI电极材料进行分析表征;运用循环伏安、充放电、电化学阻抗等测试LS/PANI电极材料电化学性能。结果表明,LS/PANI电极材料具有良好的电容性能和较好的循环稳定性;在充放电0.5 A/g的电流密度下比电容可以达到509.3 F/g,在充放电电流密度为10 A/g时,循环5 000次后仍能保留63.23%的电容。
能源是人类社会生存、发展和现代经济运行的重要保障。近年来,现代化生活对能源的需求量越来越大,能源匮乏和环境污染问题日益严重,世界面临着能源短缺的危机,对环保、低成本、可靠的储能设备的需求越来越大。超级电容器是一种具有功率密度高、循环寿命长和充电速率快的储能器件,其在能源存储和转化领域具有巨大的发展潜力和广阔的应用前
PANI通常由苯胺单体在强酸环境中,以强氧化剂为引发剂氧化聚合而成。本征态PANI自身不导电,需要掺杂质子酸来导
因此,本研究以苯胺单体为原料,以植酸为掺杂酸,采用化学氧化聚合法制备木质素磺酸盐/聚苯胺(LS/PANI)电极材料。利用场发射扫描电子显微镜及比表面积及孔径分析仪等对LS/PANI电极材料的微观形貌进行了表征,采用傅里叶变换红外光谱仪对LS/PANI电极材料官能团及化学结构进行了表征。研究了LS/PANI电极材料的电化学性能。
导电炭黑、苯胺(分析纯(AR))、过硫酸铵(APS,AR)、木质素磺酸盐(LS,Mw=5 000~10 000,木质素含量45%~50%),均购自上海麦克林生化科技有限公司;聚偏氟乙烯(PVDF,Mw>7×1
基于课题组前期的工作,本实验采用化学氧化聚合法制备木质素磺酸盐/聚苯胺(LS/PANI)电极材料(制备流程见

图1 LS/PANI电极材料制备流程图
Fig. 1 Flow chart for the preparation of LS/PANI electrode materials
使用场发射扫描电子显微镜(FESEM,Quanta 20,日本Hitachi公司)观察PANI和LS/PANI电极材料的微观形貌特征。使用比表面积及孔径分析仪(BET,ASAP 2460 3.01,美国麦克公司)测定LS/PANI电极材料的比表面积和孔径。使用傅里叶变换红外光谱仪(FT-IR,VERTEX 80V,德国Bruker公司)测试PANI和LS/PANI电极材料的化学结构,扫描范围为500~4 000 c
按照质量比8∶1∶1将PANI和LS/PANI电极材料分别与PVDF、导电炭黑混合均匀,在混合物中滴加12~15滴NMP,混合均匀后涂布在导电碳纸上,涂布面积约为1 c
以Ag/AgCl电极为参比电极,铂电极为对电极,负载涂料的碳纸为工作电极,1 mol/L H2SO4为电解质溶液,采用电化学工作站(CHI660E,上海辰华)在三电极系统下测试LS/PANI电极材料和本征态PANI电极材料的电化学性能。其中样品工作电极的循环伏安曲线(CV)的电压测试范围设置为-0.2~0.8 V,进一步研究了其倍率特性(包括10、20、30、50、100 mV/s 5种扫描速率)。以恒流充放电曲线(GCD)为参考,电压测试范围设置为-0.2~0.8 V,计算电极材料比电容相应参数。最后,使用恒电流充放电测试进一步评估复合电极的循环使用寿命,其中恒电流充放电次数为5 000次,并在10 A/g的电流密度下进行操作测试。此外,以5 mV振幅的交流电压在1
线性充放电曲线公
(1) |
式中,C为电极材料的比电容,F/g;m为电极材料负载,g;I为充放电电流,A;t为充放电时间,s;U为电压窗口,V。

图2 PANI和LS/PANI电极材料的FESEM图
Fig. 2 FESEM images of PANI and LS/PANI electrode materials
电极材料的比表面积和孔隙分布会对电极材料的电化学性能产生影

图3 LS/PANI电极材料的N2吸附-解吸曲线
Fig. 3 N2 adsorption-desorption curve for LS/PANI eletrode materials

图4 PANI和LS/PANI电极材料的FT-IR谱图
Fig. 4 FT-IR spectra of PANI and LS/PANI eletrode materials
LS与PANI复合时,苯环上引入的磺酸基团—S

图5 LS、PANI、LS/PANI元素含量及分布
Fig. 5 Elemental content and distribution of LS, PANI, and LS/PANI
为进一步探究LS/PANI电极材料的电化学性能,采用三电极体系对LS/PANI电极材料进行一系列测试,测试结果如

图6 PANI和LS/PANI电极材料电化学性能
Fig. 6 Electrochemical properties of PANI and LS/PANI electrode materials
从
循环稳定性是影响超级电容器电极性能的重要参数之一。PANI和LS/PANI电极材料的循环性能如
为了更好地阐明LS/PANI电极材料的电化学性能,在10 mHz~100 kHz频率范围内对PANI和LS/PANI电极材料进行电化学阻抗谱测试,结果见
本研究以苯胺单体为原料,木质素磺酸盐(LS)为模板,通过原位化学氧化法制备了植酸掺杂的木质素磺酸盐/聚苯胺(LS/PANI)电极材料,研究了其表面形貌、官能团及化学组成,及将其制备为超级电容器电极材料的电化学性能。
3.1 LS的引入为苯胺的聚合提供了活性位点,LS/PANI电极材料形貌上呈现为纳米球结构,明显不同于PANI电极材料的纤维条状结构。
3.2 循环伏安、恒流充放电和电化学阻抗曲线的结果均表明,LS/PANI电极材料具有较好的倍率性能和导电性能。电化学循环稳定性测试结果表明,LS/PANI电极材料表现出最佳的电化学性能和良好的循环稳定性,在充放电0.5 A/g的电流密度下,比电容可达509.3 F/g,在充放电电流密度为10 A/g时,循环5 000次后仍能保留63.23%的电容。
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