Bowl-shaped NiCo2O4 nanosheet clusters as electrode materials for high-performance asymmetric supercapacitors

Abstract

The development of transition metal oxidebased electrode materials with proper controlled structures is highly desirable for high-performance supercapacitors. However, it remains a major challenge. Here, we present the first synthesis of bowl-like NiCo 2 O 4 nanosheet clusters through a simple soft template guided hydrothermal strategy. The resulting bowl-like clusters consist of numerous NiCo 2 O 4 nanosheets with an average thickness of 19 nm and possess a mean diameter of 1 µm along with a specific surface area of 40 m 2 g −1. Remarkably, serving as an electrode material in a three-electrode system, the bowl-like NiCo 2 O 4 nanosheet clusters exhibit a high specific capacity of 1068 F g −1 at a current density of 1 A g −1 and excellent cycling stability with 90% capacitance retention after 5000 charge-discharge cycles. Meanwhile, an asymmetric supercapacitor (ASC) assembled with the NiCo 2 O 4 clusters and activated carbon (AC) as the two electrodes exhibits a high specific capacitance of 129 F g −1 at 1 A g −1 , along with a high energy density of 33 W h kg −1 at a power density of 0.66 kW kg −1. Such performance is superior to those of many commercial supercapacitors. This study opens a new avenue for the construction of ordered complex particles with controlled architectures for energy storage and conversion applications.

Hollow Concave Zinc‐Doped Co3O4 Nanosheets/Carbon Composites as Ultrahigh Capacity Anode Materials for Lithium‐Ion Batteries

“…Specific surface area and porosity are important factors for electrode materials in energy storage and conversion applications [1c,23] . The high porosity and large specific surface area can accelerate the diffusion of electrons and ions via facilitating the connection between electrode and electrolyte [24] . The porosity of HC Zn−Co NSs/C hybrids is calculated by nitrogen adsorption and desorption isotherms.…”

“…[1c,23] The high porosity and large specific surface area can accelerate the diffusion of electrons and ions via facilitating the connection between electrode and electrolyte. [24] The porosity of HC ZnÀ Co NSs/C hybrids is calculated by nitrogen adsorption and desorption isotherms. As shown in Figure 5B, adsorption and desorption curve can be assigned to type IV with hysteresis loop of type H3, demonstrating the existence of loosely packed lamellar particles and mesoporous pores.…”

Complex Hollow Bowl‐Like Nanostructures: Synthesis, Application, and Perspective

“…[ 72b ] Recently, Mai and coworkers further synthesized bowl‐like NiCo 2 O 4 nanosheets as supercapacitor electrode materials and optimized the electrochemical performance. [ 91 ] The bowl‐like NiCo 2 O 4 nanosheets cluster delivers remarkable rate performance and excellent cycling capability with 90% retention of capacitance over 5000 cycles benefiting from the combination of bowl‐like and cluster with the ultrathin nanosheets.…”

Review of NiS-Based Electrode Nanomaterials for Supercapacitors

“…With the development of nanotechnology, various kinds of electrode materials with different structures have been designed and studied [ 46 , 47 , 48 , 49 , 50 , 51 , 52 ]. The electrode materials of supercapacitors include sulfides [ 53 , 54 , 55 ], carbon materials [ 56 , 57 , 58 ], oxides [ 59 , 60 , 61 ], nitrogen materials [ 62 , 63 ], conductive polymers [ 64 ], etc. In recent years, transition metal oxides (TMOs) have become some of the most promising materials for pseudocapacitor electrodes due to their excellent chemical stability, impurity sensitivity, environmental compatibility, and resource advantages [ 65 ].…”