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A green and scalable route to yield porous carbon sheets from biomass for supercapacitors with high capacity†
Journal of Materials Chemistry A ( IF 11.9 ) Pub Date : 2017-12-13 00:00:00 , DOI: 10.1039/c7ta07579k
Cunjing Wang 1, 2, 3, 4, 5 , Dapeng Wu 1, 2, 3, 4, 5 , Hongju Wang 1, 2, 3, 4, 5 , Zhiyong Gao 1, 2, 3, 4, 5 , Fang Xu 1, 2, 3, 4, 5 , Kai Jiang 1, 2, 3, 4, 5
Affiliation  

A green and scalable route is developed to prepare hierarchical porous carbon sheets (HPCS) from biomass (cornstalk) directly under an air atmosphere instead of inert gas protection. In addition, the method adopts non-toxic NaCl and KCl mixed salt as reaction media to regulate the activation process, which avoids the corrosive and poisonous KOH and ZnCl2 reagents. Meanwhile, the porous structures of HPCS can be well-manipulated by the salt templates and the etching effects of the oxygen atom as well as the high energy molten salt media. The as-obtained HPCS consist of an ultra-thin sheet structure (∼4.6 nm in thickness) and abundant hierarchical pores, which facilitates electrolyte diffusion and ion transfer. In addition, the high specific surface area of 1588 m2 g−1 provides sufficient active sites and the rich O doping introduces pseudocapacitance. Therefore, the as-prepared HPCS exhibit a high specific capacitance of 407 F g−1 at 1 A g−1 in a three-electrode system. Moreover, the assembled symmetric supercapacitor in a two-electrode system also exhibits an outstanding specific capacitance of 413 F g−1 at 0.5 A g−1, an excellent rate capacity and a long-term cycling stability with 92.6% of initial capacitance retention after 20 000 cycles at 5 A g−1, which are comparable to those of the porous carbons activated with traditional methods. It is expected that this green and facile technique could serve as an effective and scalable method to prepare optimized HPCS with tunable porous structures from biomass for electrochemical energy storage applications.

中文翻译:

一种绿色且可扩展的途径,可以从生物质中生产出具有高容量超级电容器的多孔碳板

开发了一条绿色且可扩展的路线,以直接在空气气氛下而不是惰性气体保护下,从生物质(玉米秸秆)制备分级多孔碳板(HPCS)。另外,该方法采用无毒的NaCl和KCl混合盐作为反应介质来调节活化过程,避免了腐蚀性和有毒的KOH和ZnCl 2试剂。同时,通过盐模板和氧原子的蚀刻作用以及高能熔融盐介质,可以很好地控制HPCS的多孔结构。如此获得的HPCS由超薄的片状结构(厚度约4.6 nm)和丰富的分层孔组成,有利于电解质的扩散和离子转移。另外,高比表面积为1588 m 2 g -1提供足够的活性位,富氧掺杂会引入伪电容。因此,在三电极系统中,如此制备的HPCS在1 A g -1处显示出407 F g -1的高比电容。此外,在两电极系统中组装的对称超级电容器在0.5 A g -1时还表现出出色的413 F g -1的比电容,出色的倍率容量和长期循环稳定性,其初始电容保持率为92.6%。 5 A g -1时2万次循环与传统方法活化的多孔碳具有可比性。期望这种绿色且简便的技术可以作为一种有效且可扩展的方法,用于从生物质中制备具有可调多孔结构的优化HPCS,以用于电化学储能。
更新日期:2017-12-13
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