硝酸改性石墨毡制作超级电容器的复合电极

Composite Electrodes for Supercapacitors Fabricated with Graphite Felt Modified by Nitric Acid

为了改善石墨毡(GF)表面的疏水性以及解决生长的活性物质易脱落的问题,研究了使用浓硝酸简单的一步法活化石墨毡并且引入含氧官能团。通过实验确定了合适的浓硝酸反应条件。经浓硝酸改性后的石墨毡的比电容可以达到272.6 mF·cm^(-2),而且,发现改性后的石墨毡(MGF)更有利于活性物质生长。与MGF结合后,用于超级电容器电极的常用材料(如MnO_(2))和较不常用材料(如SnO_(2))在离子扩散速度、循环稳定性和比电容方面都有很大的改善。MnO_(2)/MGF的比电容可以达到929 mF·cm^(-2),并且在循环10 000次后还有88%的比电容保持率;对于SnO_(2)/MGF,比电容为640 mF·cm^(-2),5 000次循环后比电容保持率为93%。

To improve the hydrophobicity of the graphite felt(GF)surface and solve the problem that the grown active material on it easily falls off,a simple one-step method with concentrated HNO3 to activate graphite felt and introduce oxygen-containing functional groups were studied.The suitable reaction conditions of concentrated HNO3 were determined by experiments.The specific capacitance of the graphite felt modified by concentrated HNO3 can reach 272.6 mF·cm^(-2).Moreover,it is found that the modified graphite felt(MGF)is more conducive to the growth of the active substance.After combination with the MGF,common materials(such as MnO_(2))and less common materials(such as SnO_(2))used for supercapacitors have great improvements in ion diffusion speed,cycling stability and specific capacitance.The specific capacitance of the MnO_(2)/MGF can reach929 mF·cm^(-2),and the specific capacitance retention rate is 88%after 10 000 cycles.For SnO_(2)/MGF,the specific capacitance is 640 mF·cm^(-2) and the specific capacitance retention rate is 93%after 5 000 cycles.