School of Chemical Engineering , Yeungnam University , Gyeongsan , Gyeongbuk 38541 , Republic of Korea.
Egyptian Petroleum Research Institute , Nasr City, Cairo 11727 , Egypt.
ACS Appl Mater Interfaces. 2019 Feb 27;11(8):8040-8050. doi: 10.1021/acsami.8b21534. Epub 2019 Feb 14.
Recently, enhancement of the energy density of a supercapacitor is restricted by the inferior capacitance of negative electrodes, which impedes the commercial development of high-performance symmetric and asymmetric supercapacitors. This article introduces the in situ bulk-quantity synthesis of hydrophilic, porous, graphitic sulfur-doped carbon nano-onions (S-CNO) using a facile flame-pyrolysis technique and evaluated its potential applications as a high-performance supercapacitor electrode in a symmetric device configuration. The high-surface wettability in the as-prepared state enables the formation of highly suspended active conducting material S-CNO ink, which eliminates the routine use of binders for the electrode preparation. The as-prepared S-CNO displayed encouraging features for electrochemical energy storage applications with a high specific surface area (950 m g), ordered mesoporous structure (∼3.9 nm), high S-content (∼3.6 at. %), and substantial electronic conductivity, as indicated by the ∼80% sp graphitic carbon content. The in situ sulfur incorporation into the carbon framework of the CNO resulted in a high-polarized surface with well-distributed reversible pseudosites, increasing the electrode-electrolyte interaction and improving the overall conductivity. The S-CNOs showed a specific capacitance of 305 F g, an energy density of 10.6 W h kg, and a power density of 1004 W kg at an applied current density of 2 A g in a symmetrical two-electrode cell configuration, which is approximately three times higher than that of the pristine CNO-based device in a similar electrochemical testing environment. Even at 11 A g, the S-CNO||S-CNO device rendered an energy density (6.1 W h kg) at a deliverable power density of 5.5 kW kg, indicating a very good rate capability and power management during peak power delivery applications. Furthermore, it showed a high degree of electrochemical reversibility with excellent cycling stability, retaining ∼95% of its initial capacitance after more than 10 000 repetitive charge-discharge cycles at an applied current density of 5 A g.
最近，超级电容器的能量密度增强受到负极电容较差的限制，这阻碍了高性能对称和非对称超级电容器的商业发展。本文介绍了使用简便的火焰热解技术原位批量合成亲水性、多孔、石墨化硫掺杂碳纳米洋葱（S-CNO）的方法，并评估了其作为高性能超级电容器电极在对称器件结构中的潜在应用。在制备状态下具有高表面润湿性，可形成高度悬浮的活性导电材料 S-CNO 油墨，从而无需在电极制备中常规使用粘结剂。所制备的 S-CNO 表现出令人鼓舞的电化学储能应用特征，具有高比表面积（950 m g）、有序介孔结构（3.9nm）、高 S 含量（3.6 原子%）和高电子导电性，这表明80%的 sp 石墨化碳含量。S 原位掺入 CNO 的碳骨架中，导致表面高度极化，具有均匀分布的可逆赝位点，增加了电极-电解质的相互作用并提高了整体导电性。S-CNO 在对称两电极电池配置中，在 2 A g 的应用电流密度下，具有 305 F g 的比电容、10.6 W h kg 的能量密度和 1004 W kg 的功率密度，在类似的电化学测试环境下，比原始基于 CNO 的器件高出约三倍。即使在 11 A g 下，S-CNO||S-CNO 器件在可提供的功率密度为 5.5 kW kg 时仍能提供 6.1 W h kg 的能量密度，表明在峰值功率输送应用中具有非常好的倍率性能和功率管理能力。此外，它表现出高度的电化学可逆性和优异的循环稳定性，在 5 A g 的应用电流密度下经过 10000 多次重复充放电循环后，电容保持初始值的95%。
