增大分级结构碳纳米笼的离子传输微孔通道获得超高的能量密度和功率密度

Enlarging ion-transfer micropore channels of hierarchical carbon nanocages for ultrahigh energy and power densities

提升超级电容器能量密度而不牺牲其高功率密度是能源存储领域的不懈追求.离子液体电解液具有大的工作电压窗口,以其为电解液可提升超级电容器能量密度.但离子液体离子尺寸大、离子电导率低且粘度高,通常会导致超级电容器功率密度的减小.本文主要通过增大分级结构碳纳米笼(hCNC)电极材料的离子传输微孔通道,实现了在EMIMBF4离子液体电解液中超级电容器能量密度和功率密度的协同提升.通过Boudouard反应,在保持hCNC独特分级结构的前提下调节了贯穿碳纳米笼壁的微孔尺寸,同时,在优化的活化温度下hCNC的比表面积、孔体积和导电性均得以提升.这种独特的调节促进了大尺寸离子的传输,有效降低了等效串联电阻,从而显著提升了超级电容器的性能.优化的样品在功率密度为1.8 kW kg^(-1)时的能量密度高达153.8 W h kg^(-1),在超高功率密度480.1 kW kg^(-1)时能量密度仍能保持54.0 W h kg^(-1).本研究展示了一种通过精细调控材料微孔及相关性质开发先进电极材料的有效方法.

Increasing the energy density of supercapacitor without sacrificing its high power is an everlasting pursuit in energy storage.Using ionic liquid electrolyte with high operating voltage can increase the energy density but usually at the expense of power density due to the large ion size,low ionic conductivity and high viscosity.Herein we demonstrate a simultaneous increase of the energy and power densities with ionic liquid electrolyte(EMIMBF4)mainly by enlarging the ion-transfer micropore channels of the electrode material,i.e.,the unique hierarchical carbon nanocages(hCNC).Boudouard reaction is adopted to tune the micropore size while remaining the hierarchical framework of hCNC.Meanwhile,the specific surface area,pore volume and conductivity are also increased under optimal activation temperature.Such a unique modification boosts the large-sized ion transfer,leading to the obvious decrease of equivalent series resistance and the dramatic increase of supercapacitive performance thereof.The optimized product exhibits an energy density up to 153.8 W h kg^(-1) at the power density of 1.8 kW kg^(-1),and maintains 54.0 W h kg^(-1) even at an ultrahigh power density of 480.1 kW kg^(-1).This study demonstrates an effective way to explore advanced electrode materials by the fine regulation of micropores and related properties.