纳米纤维素复合气凝胶超级电容器的制备与性能

Preparation and Properties of NFC Composite Aerogel Supercapacitors

以纳米纤维素(NFC)、还原氧化石墨烯(RGO)及聚苯胺(PANI)为原料,利用冷冻干燥技术制备出多孔性纳米纤维素NFC复合气凝胶电极材料。通过调控NFC的羧基含量及冷冻温度,可对复合气凝胶的孔径分布及比表面积进行优化从而提高其导电性能,最后以聚乙烯醇/硫酸(PVA/H2SO4)为电解质,制备了NFC复合气凝胶超级电容器。结果表明:随着羧基含量的增加,NFC纤维间的氢键作用逐步增强使得形成交联网络更为紧密,制备的复合气凝胶孔隙尺寸变小且比表面积增大,其导电性能和电化学性能得到进一步的提升;冷冻温度直接影响形成的冰晶的尺寸大小和数量,低温冷冻制备的气凝胶孔隙数量较多且比表面积较大,形成的三维导电网络更为完整,具有良好的导电性能和电化学性能。当NFC的羧基含量为1.69 mmol/g及冷冻温度为-40℃时,复合气凝胶的比表面积为155.8 m2/g,组装的超级电容器在电流密度为0.5 A/g下其比电容为402 F/g。

Porous NFC/RGO/PANI composite aerogel electrodes have been prepared via freeze- drying process. By regulating the carboxyl content of NFC and the freezing temperature,the pore distribution and the specific surface area of composite aerogel can be optimized to obtain good structure stability and conductivity. The results showed that with the increase of the carboxyl content of NFC,the hydrogen bonding between the fibers increased steadily and the crosslinked network became tighter,resulting in smaller pore size and higher specific surface area. Furthermore,freezing temperature directly affected the size and number of the ice crystals. The pore size of composite aerogel became smaller and the specific surface area became larger with the decrease of the freezing temperature.When the carboxyl content of NFC was 1. 69 mmol/g and freezing temperature achieved- 40 ℃,the composite aerogel can obtain the specific surface area of 155. 8 m^2/ g and the assembled supercapacitor exhibited the specific capacitance of 402 F/g at a current density of 0. 5 A/g.