In Situ Construction of a Heterostructured Zn–Mo–Ni–O–S Hollow Microflower for High-Performance Hybrid Supercapacitors

The rational design of a multicomponent electrode material with hollow structures grown on the conductive substrate is an effective approach to boost the electrochemical performance of supercapacitors (SCs). However, there is still a challenge in the in situ construction of such unique structures on the conductive substrate. Herein, a heterostructured multicomponent electrode material, a Zn–Mo–Ni–O–S hollow microflower (Zn–Mo–Ni–O–S HMF) in situ grown on a Ni foam (NF), is fabricated by a simple top-down strategy. Based on the ion-exchange and Kirkendall effect, the microflowers are composed of numerous hollow nanosheets, which are covered by uniform ZnS nanoparticles with a robust adherence. Profiting from the structural merits and the synergistic effect of multiple components, the Zn–Mo–Ni–O–S HMF electrode exhibits a high areal capacitance of 4.39 C cm^–2 (6.27 F cm^–2) at 1 mA cm^–2, which is 3.6 times higher than the 0.86 C cm^–2 (1.72 F cm^–2) of the Zn–Mo–O precursor and 1.7 times higher than the 2.65 C cm^–2 (3.79 F cm^–2) of Ni₃S₂/NiMoO₄ (Mo–Ni–O–S). The Zn–Mo–Ni–O–S HMF displays an excellent cycling performance (maintaining 87.9% after 3000 cycles). The hybrid supercapacitor device is assembled by the Zn–Mo–Ni–O–S HMF as the positive electrode and active carbon (AC) as the negative electrode. The device delivers a high energy density of 60.8 Wh kg^–1 at a power density of 750.2 W kg^–1. The synthetic route provides a reference to the in situ construction of a heterostructured multicomponent electrode material for high-energy SCs.