活性炭的微结构与超级电容器性能的构效关系

以生物质柞木为原料，采用不同活化法制备具有不同结构特征的柞木基活性炭，利用N₂吸附、FT-IR、XPS、XRD、Raman光谱等表征手段对活性炭的微结构特性进行解析，探究活化方式对活性炭微结构性能的影响；微结构与超级电容器性能的构效关系。研究表明： KOH和H₃PO₄-KOH法制备的活性炭微孔发达，炭结构表面缺陷位与杂原子丰富，在低电流密度下表现出更高的比电容；H₃PO₄-KOH法制备的活性炭具备更宽的微介孔分布与孔道连通性，使其具有更好的电容保持率；CO₂、H₃PO₄和H₃PO₄-CO₂法制备的活性炭介孔发达，微孔体积小，孔道连通性差，炭结构相对完整，裸露于炭结构表面的缺陷与杂原子相对较少，尽管电容保持率较高，但比电容较低。因此，高性能的超级电容器活性炭电极应具有发达的微孔结构、较宽的微介孔分布、通畅的微介孔连通结构，同时含有更多的裸露于炭结构表面的结构缺陷与杂原子基团，从而提高超级电容器的能量密度。

Structure-property relationship between microstructure of activated carbon and supercapacitor performance

Zuomu-based activated carbon was prepared by different activation methods. The structure of activated carbon was investigated by N₂ adsorption, FT-IR, XPS, XRD, and Raman spectra. And the structure-property relationship of activated carbon was discussed. The results show that activated carbons prepared by different activation methods have different microstructure and electrochemical performance. Activated carbons prepared by KOH and H₃PO₄-KOH have well-developed micropores, abundant content of defective sites and heteroatoms on the surface of carbon matrix, which provide more energy storage space and active sites to increase the specific capacitance at low current density. The activated carbon prepared by H₃PO₄-KOH has better capacitance retention due to its wider micro mesopore distribution and pore connectivity. Activated carbons prepared by CO₂, H₃PO₄ and H₃PO₄-CO₂ activation possess well-developed mesopores, small micropore volume, poor connectivity, relatively complete carbon matrix, and fewer defects and heteroatoms exposed on the surface of the carbon matrix, resulting in the higher capacitance retention rate and lower specific capacitance. The microstructure of activated carbon has a great influence on the performance of supercapacitors. The developed microporous will provide abundant energy storage sites. The good connectivity will provide channels for fast ion transport to improve the capacitance retention. More exposed defects and heteroatomic groups on the surface or edges of the carbon matrix will be beneficial to improve the pseudo capacitance. These enable the supercapacitor to exhibit high specific capacitance and good cycling stability. Therefore, high-performance activated carbon electrodes for supercapacitors should have a well-developed microporous structure, a wide distribution of micro-mesopores, a smooth micro-mesoporous connected structure. At the same time, it contains more structural defects and heteroatom groups exposed on the surface of the carbon structure, thereby improving the energy density of the supercapacitor.