Glucose Induces Ni and S Atoms to Generate α-NiS and Their α-NiS for High-Performance Asymmetric Supercapacitors

Ni and S atoms in the same reaction system are prone to form a mixture composed of various nickel sulfide phases, and the one-step synthesis of α-NiS remains challenging. Herein, glucose was added to the precursor solution for the synthesis of nickel sulfide. With the increase of glucose, Ni and S atoms gradually transformed into α-NiS. Meanwhile, glucose gradually increases the specific surface area of the product, providing more active sites for electrochemical energy storage. The induced phase transition effect provided by glucose is only effective for α-NiS and requires a fixed concentration of reactants, which provides clear guidance for the synthesis of α-NiS. NixSy-0.5 synthesized with 0.5 g glucose has a large surface area and the highest electrochemical properties. Furthermore, the NixSy-0.5//activated carbon (AC)–asymmetric supercapacitor (ASC) has an energy density of 47.9 Wh kg–1. This work has established a crystal phase structure regulation strategy for nickel sulfide, which is conducive to the synthesis of transition metal sulfides with high electrochemical performance.