High-performance fibrous architectures and controllable fabrication methods for active nanomaterials are fundamental in the development of fiber-based supercapacitors (FSCs). Herein, we rationally designed a triple gradient structured fibrous electrode based on three-dimensional (3D) architectural approach with NiS nanoflakes (NiS NFs) in situ growth on Ni-coated graphene fiber (NiS-NiGFs) for highly energy-dense asymmetric supercapacitors. Remarkably, the Ni-metal coating imparted the NiS-NiGFs exceptional electrical conductivity (619.8 S cm), mechanical strength (335.0 MPa), and flexibility without significantly compromising its density. Moreover, the unique 3D interconnected ultrathin NiS NFs significantly increase the contact area between the electrode and the electrolyte solution, providing abundant redox activity to facilitate ion transport and accumulation. Therefore, the fibrous electrode showcased a remarkable areal specific capacitance of 1387.6 mF cm at 3 mA cm in 3 M KOH electrolyte, while its asymmetric FSCs delivered an impressive areal energy density of 15.6 μW h cm at power density of 1.0 mW cm along with durable cycle life (86.7 % of the initial specific capacitance retention over 10,000 cycles). In summary, the featured work provides a facile but robust electrode design to realize highly energy-dense flexible energy storage devices for next-generation wearable industries.

中文翻译：

---

用于高性能不对称超级电容器的 3D 架构三梯度石墨烯基纤维电极

活性纳米材料的高性能纤维结构和可控制造方法是纤维超级电容器（FSC）开发的基础。在此，我们合理地设计了基于三维（3D）结构方法的三梯度结构纤维电极，其中NiS纳米片（NiS NF）在镀镍石墨烯纤维（NiS-NiGF）上原位生长，用于高能量密度不对称超级电容器。值得注意的是，镍金属涂层赋予 NiS-NiGF 优异的导电性（619.8 S cm）、机械强度（335.0 MPa）和柔韧性，而不会显着影响其密度。此外，独特的3D互连超薄NiS NF显着增加了电极和电解质溶液之间的接触面积，提供丰富的氧化还原活性以促进离子传输和积累。因此，纤维电极在 3 M KOH 电解质中在 3 mA cm 下表现出 1387.6 mF cm 的显着面积比电容，而其不对称 FSC 在 1.0 mW cm 的功率密度下提供了令人印象深刻的 15.6 μW h cm 的面积能量密度以及耐用性循环寿命（10,000 次循环后初始比电容保持率为 86.7%）。总之，该专题工作提供了一种简便而稳健的电极设计，可为下一代可穿戴行业实现高能量密度的柔性储能设备。