低温脱除超级电容器用多孔炭含氧官能团  

Removal the oxygen-containing groups of porous carbon under low-temperature for supercapacitors

作　　者：杨婷 尹立坤 韩宇 毕然 郑壮壮 张亚楠 陈明鸣[1] YANG Ting;YIN Likun;HAN Yu;BI Ran;ZHENG Zhuangzhuang;ZHANG Yanan;CHEN Mingming(School of Chemical Engineering and Technology,Tianjin University,Tianjin 300072,China;Comprehensive Energy Research Center,Institute of Science and Technology,China Three Gorges Corporation,Beijing 100038,China)

机构地区：[1]天津大学化工学院,天津300072 [2]中国长江三峡集团有限公司科学技术研究院综合能源技术研究中心,北京100038

出　　处：《化学工业与工程》2022年第5期66-77,共12页Chemical Industry and Engineering

基　　金：国家自然科学基金资助项目(22078228)。

摘　　要：提升双电层超级电容器(EDLCs)能量密度的关键在于提高多孔炭电极材料的耐电压特性。然而目前提高多孔炭耐电压特性的难点是既脱除多孔炭的含氧基团、又不破坏多孔炭的层次孔结构。对此,选择镍基催化剂、利用催化剂表面发生的氢溢流现象,实现低温条件下脱除多孔炭的含氧基团,得到低氧含量的多孔炭。与H气氛下的热还原脱氧过程相比,基于氢溢流现象的脱氧过程除了热解反应和加氢反应,还包括高活性氢原子参与的剧烈加氢反应。此外,考察了基于一级氢溢流和二级氢溢流现象的多孔炭脱氧过程的作用机制。由于镍纳米颗粒和多孔炭之间存在Ni—O—C键和Ni—C键,一级氢溢流抑制了多孔炭含氧基团的脱除。二级氢溢流避免了Ni—C键和Ni—O—C键的形成,解离的高活性氢原子可在厘米级别的长距离范围内扩散,能更有效脱除多孔炭表面的C—O、C=O等含氧基团。此外,二级氢溢流脱氧后得到的多孔炭(PC-Ni-655)的碳层结构的有序度提高且孔道结构没有被破坏。当PC-Ni-655应用于EDLCs时,在3.3 V的高电压窗口下表现出较小的自放电现象和良好的循环稳定性(在1 A·g^(-1)循环5 000圈后,容量保持率为87.9%)。The key to increasing the energy density of electric double-layer capacitors(EDLCs) is to widen the voltage window of EDLCs and improve the withstanding voltage characteristics of porous carbon electrode materials. However, the current difficulty in improving the withstanding voltage characteristics of porous carbon is to reduce the content of oxygen-containing functional groups without destroying the hierarchical pore structure. In this paper, by using a nickel-based catalyst, the hydrogen spillover phenomenon on the surface of the catalyst was applied to remove the oxygen-containing groups of the porous carbon under low temperature conditions, thereby obtaining a porous carbon with low oxygen content. Compared with thermal reduction(Hatmosphere), in addition to pyrolysis and hydrogenation reactions, the reduction process under hydrogen spillover also includes violent hydrogenation reactions involving highly active hydrogen atoms. Besides, the mechanisms of removing oxygen-containing groups under the primary hydrogen spillover and second hydrogen spillover are investigated and compared in detail. Under the primary hydrogen spillover, due to the strong chemical interaction(Ni—O—C bond and Ni—C bond) between the nickel nanoparticles and the porous carbon, the removal of oxygen-containing groups in the porous carbon is inhibited. However, under the second hydrogen spillover, the Ni—C bond and Ni—O—C bond are avoided, and the dissociated highly active hydrogen atoms diffuse for a long distance at the centimeter level, which can more effectively remove C—O and C=O groups. In addition, under the second hydrogen spillover, the crystallinity of carbon layer structure in obtained porous carbon PC-Ni-655 is improved and the pore structure is not destroyed. As a result, when PC-Ni-655 was applied as the electrode material of EDLCs, a small self-discharge phenomenon and long-term cycling stability(a capacity retention rate is 87.9% over 5 000 cycles at 1 A·g^(-1)) with a high operation voltage of 3.3 V were o

关 键 词：超级电容器 含氧官能团 氢溢流 多孔炭 耐电压特性 电化学性能 

分 类 号：TM53[电气工程—电器]