Department of Chemical and Biological Engineering, Drexel University , 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States.
ACS Appl Mater Interfaces. 2016 Aug 24;8(33):21261-9. doi: 10.1021/acsami.6b03463. Epub 2016 Aug 9.
Freestanding, binder-free supercapacitor electrodes based on high-purity polyaniline (PANI) nanofibers were fabricated via a single step electrospinning process. The successful electrospinning of nanofibers with an unprecedentedly high composition of PANI (93 wt %) was made possible due to blending ultrahigh molecular weight poly(ethylene oxide) (PEO) with PANI in solution to impart adequate chain entanglements, a critical requirement for electrospinning. To further enhance the conductivity and stability of the electrodes, a small concentration of carbon nanotubes (CNTs) was added to the PANI/PEO solution prior to electrospinning to generate PANI/CNT/PEO nanofibers (12 wt % CNTs). Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) porosimetry were conducted to characterize the external morphology of the nanofibers. The electrospun nanofibers were further probed by transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The electroactivity of the freestanding PANI and PANI/CNT nanofiber electrodes was examined using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. Competitive specific capacitances of 308 and 385 F g(-1) were achieved for PANI and PANI-CNT based electrodes, respectively, at a current density of 0.5 A g(-1). Moreover, specific capacitance retentions of 70 and 81.4% were observed for PANI and PANI-CNT based electrodes, respectively, after 1000 cycles. The promising electrochemical performance of the fabricated electrodes, we believe, stems from the porous 3-D electrode structure characteristic of the nonwoven interconnected nanostructures. The interconnected nanofiber network facilitates efficient electron conduction while the inter- and intrafiber porosity enable excellent electrolyte penetration within the polymer matrix, allowing fast ion transport to the active sites.
通过一步静电纺丝工艺制备了基于高纯度聚苯胺 (PANI) 纳米纤维的独立、无粘结剂超级电容器电极。由于在溶液中混入超高分子量聚环氧乙烷 (PEO) 以赋予足够的链缠结，从而实现了具有空前高 PANI 组成 (93wt%) 的纳米纤维的成功静电纺丝，这是静电纺丝的关键要求。为了进一步提高电极的导电性和稳定性，在静电纺丝前将少量的碳纳米管 (CNT) 添加到 PANI/PEO 溶液中，以生成 PANI/CNT/PEO 纳米纤维 (12wt%CNT)。通过扫描电子显微镜 (SEM) 和 Brunauer-Emmett-Teller (BET) 比表面积法对纳米纤维的外部形态进行了表征。通过透射电子显微镜 (TEM)、X 射线衍射 (XRD) 和傅里叶变换红外光谱 (FT-IR) 对电纺纳米纤维进行了进一步探测。使用循环伏安法、恒电流充放电和电化学阻抗谱研究了独立的 PANI 和 PANI/CNT 纳米纤维电极的电活性。在电流密度为 0.5A g-1 时，PANI 和基于 PANI-CNT 的电极分别实现了 308 和 385 F g-1 的竞争比电容。此外，在 1000 次循环后，PANI 和基于 PANI-CNT 的电极的比电容保持率分别为 70%和 81.4%。我们相信，所制备的电极具有有前途的电化学性能，这源于无纺非织造相互连接的纳米结构的多孔 3-D 电极结构特征。相互连接的纳米纤维网络促进了有效的电子传导，而纤维间和纤维内的孔隙使聚合物基体内部的电解质能够充分渗透，从而使离子能够快速传输到活性位点。
