One-Step Hydrothermal Synthesis of Glucose-Induced Low Crystallinity NiCo-Based Layered Double Hydroxides for High-Performance Asymmetric Supercapacitors.

Abstract

In order to improve the electrochemical performance of NiCo-based layered double hydroxide (NiCoLDH), the synthesis of low-crystallinity NiCoLDH was induced by the adsorption of glucose and NiCoLDH. The results showed that glucose could not only effectively regulate the pore structure and morphology of NiCoLDH, but also had a regular effect on crystallinity. Pure phase NiCoLDH had higher crystallinity. When the mass of glucose is 0.05 g, the prepared NiCoLDH-0.05 is a short-range ordered structure embedded in the amorphous matrix. The crystallinity of the product decreases further with the further increase of glucose mass. Since the ordered structures have higher electrical conductivity, and amorphous structures have more defects and active sites, the structure of NiCoLDH-0.05 is conducive to achieving the best electrochemical performance. Electrochemical test results show that NiCoLDH-0.05 has a high specific capacitance, about 12 times that of the pure phase NiCoLDH, the mass of glucose is higher than or below 0.05 g, the specific capacitance will be further reduced. NiCoLDH-0.05 and activated carbon assembled into an asymmetric supercapacitor have a power density of 400 W kg^-1 at an energy density of 32.7 Wh kg^-1. This study provides a new idea for obtaining excellent electrochemical properties by adjusting LDH crystallinity.