Zhang Caiyun, Zhu Xiaohong, Wang Zhongxing, Sun Ping, Ren Yinjuan, Zhu Jiliang, Zhu Jianguo, Xiao Dingquan
Department of Materials Science, Sichuan University, Chengdu 610064, People's Republic of China.
Nanoscale Res Lett. 2014 Sep 13;9(1):490. doi: 10.1186/1556-276X-9-490. eCollection 2014.
Graphene has attracted much attention since it was firstly stripped from graphite by two physicists in 2004, and the supercapacitor based on graphene has obtained wide attention and much investment as well. For practical applications of graphene-based supercapacitors, however, there are still many challenges to solve, for instance, to simplify the technological process, to lower the fabrication cost, and to improve the electrochemical performance. In this work, graphene/MnO2 composites are prepared by a microwave sintering method, and we report here a relatively simple method for the supercapacitor packaging, i.e., dipping Ni-foam into a graphene/MnO2 composite solution directly for a period of time to coat the active material on a current collector. It is found that the microwave reaction time has a significant effect on the microstructure of graphene/MnO2 composites, and consequently, the electrochemical properties of the supercapacitors based on graphene/MnO2 composites are strongly microstructure dependent. An appropriately longer microwave reaction time, namely, 15 min, facilitates a very dense and homogeneous microstructure of the graphene/MnO2 composites, and thus, excellent electrochemical performance is achieved in the supercapacitor device, including a high specific capacitance of 296 F/g and a high capacitance retention of 93% after 3,000 times of charging/discharging cycles.
81.05.ue; 78.67.Sc; 88.80.fh.
自2004年两位物理学家首次从石墨中剥离出石墨烯以来，它就备受关注，基于石墨烯的超级电容器也获得了广泛关注和大量投资。然而，对于基于石墨烯的超级电容器的实际应用，仍有许多挑战需要解决，例如简化工艺流程、降低制造成本以及提高电化学性能。在这项工作中，通过微波烧结法制备了石墨烯/MnO₂复合材料，并且在此我们报道一种相对简单的超级电容器封装方法，即将泡沫镍直接浸入石墨烯/MnO₂复合溶液中一段时间，以便将活性材料涂覆在集流体上。发现微波反应时间对石墨烯/MnO₂复合材料的微观结构有显著影响，因此，基于石墨烯/MnO₂复合材料的超级电容器的电化学性能强烈依赖于微观结构。适当延长微波反应时间，即15分钟，有利于形成非常致密且均匀的石墨烯/MnO₂复合材料微观结构，从而在超级电容器器件中实现优异的电化学性能，包括296 F/g的高比电容以及在3000次充放电循环后93%的高电容保持率。
81.05.ue；78.67.Sc；88.80.fh。
