Constructing Hierarchical CoGa<sub>2</sub>O<sub>4</sub>–S@NiCo-LDH Core–Shell Heterostructures with Crystalline/Amorphous/Crystalline Heterointerfaces for Flexible Asymmetric Supercapacitors
Jiangpeng Li, Sha Li, Yueyue Huang, Zhuo Liu, Cheng Chen, Qian Ding, Haijiao Xie, Yongqian Xu, Shiguo Sun, Hongjuan Li
Abstract
The rational design and construction of composite electrodes are crucial for overcoming the issues of poor working stability and slow ionic electron mobility of a single component. Nevertheless, it is a big challenge to construct core–shell heterostructures with crystalline/amorphous/crystalline heterointerfaces in straightforward and efficient methods. Here, we have successfully converted a portion of crystalline CoGa 2 O 4 into the amorphous phase by employing a facile sulfidation process (denoted as CoGa 2 O 4 –S), followed by anchoring crystalline NiCo-layered double hydroxide (denoted as NiCo-LDH) nanoarrays onto hexagonal plates and nucleation points of CoGa 2 O 4 –S, synthesizing dual-type hexagonal and flower-like 3D CoGa 2 O 4 –S@NiCo-LDH core–shell heterostructures with crystalline/amorphous/crystalline heterointerfaces on carbon cloth. Furthermore, we further adjust the Ni/Co ratio in LDH, achieving precise and controllable core–shell heterostructures. Benefiting from the abundant crystalline/amorphous/crystalline heterointerfaces and synergistic effect among various components, the CoGa 2 O 4 –S@Ni 2 Co 1 -LDH electrode exhibits a specific capacity of 247.8 mAh·g –1 at 1 A·g –1 and good rate performance. A CoGa 2 O 4 –S@Ni 2 Co 1 -LDH//AC flexible asymmetric supercapacitor provides an energy density of 58.2 Wh·kg –1 at a power density of 850 W·kg –1 and exhibits an impressive capacitance retention of 105.7% after 10,000 cycles at 10 A·g –1 . Our research provides profound insights into the design of other similar core–shell heterostructures.