Wu Mao-Sung, Fu Yan-Hao
Department of Chemical and Materials Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 807, Taiwan.
Nanoscale. 2014 Apr 21;6(8):4195-203. doi: 10.1039/c3nr05836k. Epub 2014 Mar 7.
Expanded mesocarbon microbeads (EMCMBs) with graphene oxide (GO) sheets were prepared by expanding graphitized mesocarbon microbeads (MCMBs) using a simple solution-based oxidative process. EMCMB-supported nickel nanoparticles with an average size of 4.6 nm were fabricated by an electrophoretic deposition (EPD) method in the presence of nickel nitrate additive. Nickel ions were self-assembled on the fluffy GO sheets resulting in a more positively charged EMCMB particle for facilitating EPD and dispersion. After heat treatment at 300 °C, GO could be converted to graphene which could provide a conductive network for facilitating the transport of electrons. Well-dispersed nickel nanoparticles on graphene sheets could act as a redox center to allow storage of extra charge and a nanospacer to prevent the graphene sheets from restacking. The specific capacitance of EMCMB-supported nickel electrode could reach 491 F g(-1), which is much higher than that of EMCMB electrode (43 F g(-1)) and bare nickel electrode (146 F g(-1)) at a discharge current of 5 A g(-1). More importantly, the EMCMB-supported nickel electrode is capable of delivering a high specific capacitance of 440 F g(-1) at a discharge current of 50 A g(-1), and could pave the way towards high-rate supercapacitors.
通过简单的基于溶液的氧化过程对石墨化中间相炭微球（MCMB）进行膨胀，制备了带有氧化石墨烯（GO）片层的膨胀中间相炭微球（EMCMB）。在硝酸镍添加剂存在的情况下，采用电泳沉积（EPD）方法制备了平均尺寸为4.6 nm的EMCMB负载镍纳米颗粒。镍离子在蓬松的GO片层上自组装，形成带更多正电荷的EMCMB颗粒，便于进行电泳沉积和分散。在300℃热处理后，GO可转化为石墨烯，其能提供导电网络以促进电子传输。石墨烯片层上分散良好的镍纳米颗粒可作为氧化还原中心，用于存储额外电荷，还可作为纳米间隔物防止石墨烯片层重新堆叠。在5 A g(-1)的放电电流下，EMCMB负载镍电极的比电容可达491 F g(-1)，远高于EMCMB电极（43 F g(-1)）和裸镍电极（146 F g(-1)）。更重要的是，EMCMB负载镍电极在50 A g(-1)的放电电流下能够提供440 F g(-1)的高比电容，可为高倍率超级电容器的发展铺平道路。
