Abstract Rational design of structures plays a key role in achieving high capacitive performances for electrode materials of supercapacitors. In this study, polydopamine based N-doped carbon spheres (NCSs)@Ni(OH)2 nanocomposites with integrated core-shell structure are developed, in which ultrathin nanosheets of α-Ni(OH)2 are vertically and tightly grafted on NCSs by a fast and scalable chemical bath deposition method. The conductive skeleton of NCSs not only facilitates fast electron transfer, but also enhances the structure stability of α-Ni(OH)2. The effects of synthetic conditions such as NCSs content, deposition time of Ni(OH)2 and oxidant amount on the morphology, structure and capacitive performance of NCSs@Ni(OH)2 nanocomposites are thoroughly investigated. The optimized nanocomposite exhibits excellent electrochemical performances with ultrahigh specific capacitance of 840 C g−1 at 2 A g−1 and 640 C g−1 even at ultrahigh current density of 20 A g−1. Based on NCSs@Ni(OH)2, the hybrid supercapacitor shows maximum energy density of 33.5 Wh kg−1 at the power density of 0.4 kW kg−1 and the energy density still remains 20.4 W h kg−1 when the power density increases to 4 kW kg−1.

中文翻译：

---

用于超级电容器应用的聚多巴胺基 N 掺杂碳球上超薄 α-Ni(OH)2 纳米片的可控和快速生长

摘要 结构的合理设计对于实现超级电容器电极材料的高电容性能起着关键作用。本研究开发了基于聚多巴胺的 N 掺杂碳球 (NCSs)@Ni(OH)2 纳米复合材料，其具有集成的核壳结构，其中 α-Ni(OH)2 的超薄纳米片通过以下方式垂直紧密地接枝在 NCSs 上一种快速且可扩展的化学浴沉积方法。NCSs 的导电骨架不仅有利于快速电子转移，而且增强了 α-Ni(OH)2 的结构稳定性。深入研究了NCSs含量、Ni(OH)2沉积时间和氧化剂用量等合成条件对NCSs@Ni(OH)2纳米复合材料的形貌、结构和电容性能的影响。优化后的纳米复合材料表现出优异的电化学性能，即使在 20 A g-1 的超高电流密度下，2 A g-1 和 640 C g-1 的超高比电容也达到 840 C g-1。基于 NCSs@Ni(OH)2，混合超级电容器在 0.4 kW kg-1 的功率密度下显示出 33.5 Wh kg-1 的最大能量密度，并且当功率密度增加时能量密度仍然保持在 20.4 W h kg-1到 4 kW kg−1。