铜改性生物质基分级多孔炭及其电容性能

Cu-modified biomass-derived activated carbons for high performance supercapacitors

多孔炭由于其较长的循环寿命和前驱体种类繁多而被广泛应用于超级电容器中,但其电容量较低,导致能量密度较低。本文通过简单、高效的炭化和活化方法合成了铜修饰的生物质衍生的分级多孔炭(Cu-AC-x),混合价态(CuO、Cu_(2)O、Cu^(0))的铜纳米颗粒均匀分散在其表面。作为超级电容器电极材料,由于分级孔结构提供的快速电子/离子转移途径,以及Cu混合价态之间的加速氧化还原反应,Cu-AC-x纳米复合材料表现出良好的电化学性能。在三电极体系中,CuAC-2在0.5 A g^(-1)下表现出360 F g^(-1)的高比电容,是AC(163 F g^(-1))的1.21倍。此外,当将其组装对称电容器时,该器件在0.5 A g^(-1)下的比电容为143.44 F g^(-1),经6000次循环后的循环稳定性为81.8%。

Porous carbons are widely used in supercapacitors,owing to their long cycle life and natural abundance.However,most of these electrode materials give a low capacitance,which leads to low energy density.Cu-doped biomass-derived activated carbons(Cu-ACs)were synthesized using a simple,low-cost carbonization and KOH activation method.The copper nanoparticles had mixed valence states(CuO,Cu_(2)O,Cu^(0))and were uniformly dispersed on the surface of the AC.Due to the fast electron/ion transfer paths provided by the pore structure,and an accelerated redox reaction between the three Cu species,the Cu-ACs achieved an excellent capacitive performance.In a three-electrode system,the Cu-AC sample prepared by KOH activation with a KOH/(Cu+char)mass ratio of 2 had a high specific capacitance of 360 F g^(-1) at 0.5 A g^(-1),1.21 times that of AC(163 F g^(-1)).When it was fabricated into a symmetric capacitor,the device had a good electrochemical performance with a specific capacitance of 143.44 F g^(-1) at 0.5 A g^(-1)and a good cyclic stability with an 81.8%capacitance retention after 6000 cycles.