Eco-friendly and low-cost methods for the scalable production of high-quality graphene are highly recommended for its use in electric or electronic applications, as the commonly employed graphene oxide (GO) route is associated with drastic oxidizing conditions and toxic reducing agents, where the resultant reduced graphene oxide (rGO) fails to display the electrical properties of pristine graphene. Herein, we present a new green and facile in-situ approach for the high-yielding synthesis of a carbon sphere/graphene nanocomposite through graphite exfoliation via a simple sucrose-mediated mechanical peel-off via ball-milling followed by hydrothermal treatment. The anchoring of carbon spheres on the graphene sheets and oxygen-containing functional groups on the carbon atoms have been revealed using FESEM imaging and XPS analysis respectively. The electrical double layer capacitance together with the pseudocapacitance make the carbon sphere/graphene electrodes promising for energy storage applications, with a high specific capacitance (511 F/g @2 A/g current density) and long-term stability (86.2% capacitance retention @10000 cycles). The high performance of the carbon sphere/graphene nanocomposite is achieved through improved hybridization of the two materials and the consequent synergistic effect as an outcome of the unique in-situ fabrication approach; in addition, insertion of the carbon spheres prevents the restacking of the graphene layers. A symmetric coin cell supercapacitor was constructed from the carbon sphere/graphene nanocomposite and the device displayed a high specific capacitance of 1344 mF/g at 8 mA/g and a good energy density of 186 mWh/kg at a high specific power of 4000 mW/kg. The practical applicability of the fabricated supercapacitor as an energy storage device has also been investigated.

中文翻译：

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用于高性能超级电容器的碳球/石墨烯的原位绿克级合成

强烈建议在电气或电子应用中使用环保且低成本的大规模生产高质量石墨烯的方法，因为常用的氧化石墨烯（GO）路线与剧烈的氧化条件和有毒还原剂有关，其中所得的还原氧化石墨烯（rGO）无法显示原始石墨烯的电性能。在此，我们提出了一种新的绿色且简便的原位方法，通过球磨和水热处理的简单蔗糖介导的机械剥离，通过石墨剥离来高产合成碳球/石墨烯纳米复合材料。分别使用 FESEM 成像和 XPS 分析揭示了石墨烯片上碳球的锚定和碳原子上含氧官能团的锚定。双层电容与赝电容使碳球/石墨烯电极在储能应用中具有广阔的前景，具有高比电容（511 F/g@2 A/g电流密度）和长期稳定性（86.2%电容保持率） @10000 次循环）。碳球/石墨烯纳米复合材料的高性能是通过改进两种材料的杂化以及独特的原位制造方法所产生的协同效应来实现的；此外，碳球的插入可以防止石墨烯层的重新堆叠。由碳球/石墨烯纳米复合材料构建了对称纽扣电池超级电容器，该器件在 8 mA/g 电流下表现出 1344 mF/g 的高比电容，在 4000 mW 高比功率下表现出 186 mWh/kg 的良好能量密度/公斤。还研究了所制造的超级电容器作为储能装置的实际适用性。