Rani Janardhanan R, Thangavel Ranjith, Oh Se-I, Lee Yun Sung, Jang Jae-Hyung
School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, Gwangju 61005, Korea.
Faculty of Applied Chemical Engineering, Chonnam National University, Gwangju 61186, Korea.
Nanomaterials (Basel). 2019 Jan 24;9(2):148. doi: 10.3390/nano9020148.
Present state-of-the-art graphene-based electrodes for supercapacitors remain far from commercial requirements in terms of high energy density. The realization of high energy supercapacitor electrodes remains challenging, because graphene-based electrode materials are synthesized by the chemical modification of graphene. The modified graphene electrodes have lower electrical conductivity than ideal graphene, and limited electrochemically active surface areas due to restacking, which hinders the access of electrolyte ions, resulting in a low energy density. In order to solve the issue of restacking and low electrical conductivity, we introduce thiol-functionalized, nitrogen-doped, reduced graphene oxide scrolls as the electrode materials for an electric double-layer supercapacitor. The fabricated supercapacitor exhibits a very high energy/power density of 206 Wh/kg (59.74 Wh/L)/496 W/kg at a current density of 0.25 A/g, and a high power/energy density of 32 kW/kg (9.8 kW/L)/9.58 Wh/kg at a current density of 50 A/g; it also operates in a voltage range of 0~4 V with excellent cyclic stability of more than 20,000 cycles. By suitably combining the scroll-based electrode and electrolyte material, this study presents a strategy for electrode design for next-generation energy storage devices with high energy density without compromising the power density.
就高能量密度而言，目前用于超级电容器的最先进的基于石墨烯的电极仍远未达到商业要求。实现高能量超级电容器电极仍然具有挑战性，因为基于石墨烯的电极材料是通过石墨烯的化学改性合成的。改性石墨烯电极的电导率低于理想石墨烯，并且由于重新堆叠导致电化学活性表面积有限，这阻碍了电解质离子的进入，从而导致能量密度较低。为了解决重新堆叠和低电导率的问题，我们引入了硫醇功能化、氮掺杂的还原氧化石墨烯卷作为双电层超级电容器的电极材料。所制备的超级电容器在电流密度为0.25 A/g时表现出206 Wh/kg（59.74 Wh/L）/496 W/kg的非常高的能量/功率密度，在电流密度为50 A/g时表现出32 kW/kg（9.8 kW/L）/9.58 Wh/kg的高功率/能量密度；它还在0~4 V的电压范围内运行，具有超过20,000次循环的优异循环稳定性。通过适当地组合基于卷的电极和电解质材料，本研究提出了一种用于下一代高能量密度储能装置的电极设计策略，而不牺牲功率密度。
