고체 전해질 슈퍼 커패시터를위한 양극 전극으로서의 NiCo2O4 산화물의 제조에 관한 연구

Abstract

The design and development of nanomaterial has become central to the advancement of pseudocapacitive performance. Many one-dimensional nanostructures, two-dimensional nanostructures, and three-dimensional hierarchical structures composed of these building blocks have been synthesized as supercapacitive materials by different methods. In this thesis, a facile two-step method is developed for large-scale growth of ultrathin mesoporous nickel cobaltite (NiCo2O4) nanosheet on conductive nickel (Ni) foam with robust adhesion as a high-performance electrode for electrochemical capacitors. The synthesis involves co-electrodeposition of a bimetallic nickel cobalt hydroxide precursor on a Ni foam support and a subsequent thermal transformation to spinel mesoporous NiCo2O4. The nickel-foam-supported ultrathin mesoporous NiCo2O4 nanosheets promise fast electron and ion transport, a large electroactive surface area, and excellent structural stability. As a result, the NiCo2O4 electrodeposited for one cycle exhibits a high specific capacitance of up to 1734.9 F g−1 at a current density of 2 A g−1, the sample retains approximately 87.3% of its maximum capacitance even after 3500 continuous charge–discharge cycles at a consistently high current density of 30 A g−1. Furthermore, a solid-state asymmetric supercapacitor (ASC) was assembled using carbon nanotubes as the negative electrode, NiCo2O4 nanosheet arrays as the positive electrode, and a polyvinyl alcohol–KOH gel as the solid-state electrolyte. The ASC shows superior electrochemical behavior and an energy density of 42.25 W h kg−1 at a power density of 298.79 W kg−1.