糠醛渣多孔炭的制备及其在超级电容器中的应用

随着经济的发展和社会的进步,人们对具有长的循环寿命、高的功率密度和绿色廉价的能源设备的需求逐渐增加,基于生物质活性炭的超级电容器近年来备受关注。然而,生物质基活性炭的电化学性能仍然缺少竞争力,此外,对其微观结构的控制也是较大难题。笔者以糠醛渣为原料,KOH为活化剂,在氩气氛围下通过两步炭化的方法制备三维多孔炭材料,并将制备的多孔炭用做超级电容的电极材料。通过SEM、TEM、Raman、XPS、XRD等手段系统分析表征了所获多孔炭材料的形貌、结构、组成,并探讨活化剂的比例对糠醛渣多孔炭结构性能的影响。研究结果表明:当KOH和糠醛渣的质量比为3:1时,所制备的多孔炭材料比表面积为2 164.3 m2/g,具有良好的电容性能(当电流密度1 A/g时,比电容为235.6 F/g)、倍率性能和循环稳定性(当循环充放电10 000 次后,比电容仍能保留96%以上)。本研究从生物精炼废弃物中制备了性能优异的超级电容器用活性炭,为降低高性能超级电容器成本,实现生物质的高值化应用提供新思路。
With increasing demand of green and inexpensive power source with long cycle life and high power density, supercapacitors based on biomass-based active carbons have attracted wide attention in recent years. However, the electrochemical performances of the biomass-based active carbons are still not competitive and the control of their microstructure still remains a challenge. Therefore, waste biomass furfural residue is employed as raw material to prepare porous carbon for supercapacitors. The waste biomass-based porous carbon with obviously improved electrochemical performance was prepared by two-step carbonization process under the protection of argon by using KOH as activated agent. The morphology, structure and composition of final porous carbon materials were characterized by SEM, TEM, Raman, XPS, XRD, etc. The effect of different KOH/precursor weight ratio on the textural properties and surface chemistry of KOH-activated carbons was examined. The results showed that the natural hierarchical structure of furfural residue can be preserved and the furfural residue based porous carbon materials(FRC)have 3D interconnected porous structure, and the sample synthesized at 3:1 ratio of KOH and furfural residue, under 750 ℃ has the highest BET surface area of 2 164.3 m2/g. When applied as the electrode material of supercapacitor device, the FRC exhibits outstanding capacitive performance with specific capacitance of 298 F/g at 0.5 A/g, good rate capacitive behavior, and excellent cycling stability(97% of capacitance retention after 10 000 cycles)in 6 mol/L KOH electrolyte. The specific energy density of the device is about 8.18 W/(h？kg)at a current density of 0.5 A/g. And the specific energy density is still 4.58 W/(h？kg)with a high power density of 3 750 W/kg, which is superior to that of the commercial devices based on two symmetric activated carbon electrodes. These porous carbons derived from low-cost waste biomass are expected to be ideal electrode material for supercapacitors. The present approach represents a sustainable platform towards the rational design of carbon materials and the efficient utilization