Although bimetallic nickel-cobalt sulfides (Ni/Co-S) have shown promising candidates as pseudocapacitive materials with excellent electrochemical performance, achieving high energy density, high power density, and good cyclability of Ni/Co-S electrode remains a challenge. In this study, the graphene foam (GF) with a three-dimensional (3D) skeleton was successfully prepared using a chemical vapor deposition (CVD) method. Subsequently, Ni/Co-S was in situ grown on the GF through a two-step hydrothermal method. A series of Ni/Co-S@GF-x (x=1, 2, 3) electrodes were prepared and optimized for electrochemical performance by regulating the molar ratio of Ni/Co salt precursors (3:1, 4:1, 5:1). The abundant pore structure of Ni/Co-S@GF not only facilitates ion migration, but also provides numerous electrochemical redox active sites for reactions. When utilized as electrodes in supercapacitors, the Ni/Co-S@GF-2 with a Ni/Co salt’s molar ratio of 4:1 displays a specific capacity of 4.68 C cm−2 at 1 mA cm−2. Furthermore, an asymmetric supercapacitor (ASC) was assembled using the optimal Ni/Co-S@GF-2 as cathode and Walnut shell-derived porous carbon as anode to evaluate the actual energy storage characteristics of the device. The ASC delivers a high power density of 822.86 mW cm−2 at an energy density of 32.0 mWh cm−2. This work presents a promising approach for designing and preparing nickel-cobalt sulfides for application in flexible energy storage devices.

中文翻译：

---

在石墨烯泡沫上生长的双金属镍钴硫化物用于高性能不对称超级电容器


尽管双金属镍钴硫化物（Ni/Co-S）已成为具有优异电化学性能的赝电容材料，但实现 Ni/Co-S 电极的高能量密度、高功率密度和良好的循环性能仍然是一个挑战。在这项研究中，采用化学气相沉积（CVD）方法成功制备了具有三维（3D）骨架的石墨烯泡沫（GF）。随后，通过两步水热法在GF上原位生长Ni/Co-S。通过调节 Ni/Co 盐前驱体的摩尔比（3:1、4:1、5）制备了一系列 Ni/Co-S@GF-x (x=1, 2, 3) 电极并优化了电化学性能。 ：1）。 Ni/Co-S@GF丰富的孔隙结构不仅有利于离子迁移，而且为反应提供了大量的电化学氧化还原活性位点。当用作超级电容器的电极时，Ni/Co盐摩尔比为4:1的Ni/Co-S@GF-2在1 mA cm−2下表现出4.68 C cm−2的比容量。此外，使用最佳的Ni/Co-S@GF-2作为阴极和核桃壳衍生的多孔碳作为阳极组装了不对称超级电容器（ASC），以评估该装置的实际储能特性。 ASC 在 32.0 mWh cm−2 的能量密度下提供 822.86 mW cm−2 的高功率密度。这项工作为设计和制备用于柔性储能装置的镍钴硫化物提供了一种有前途的方法。