Dual-ion pre-inserted Mo glycerate template for constructing NiMo-OS core–shell structure with boosting performance in zinc ions hybrid supercapacitors

Zinc ion hybrid supercapacitors (ZHS) have received much attention due to the enhanced potential window range and high specific capacity. However, the appropriate positive materials with high electrochemical performance are still a challenge. Herein, NH₄⁺ and glycerate anions pre-inserted Mo glycerate (N-MoG) spheres are synthesized and serve as the template to form NH₄⁺ intercalated Ni₃S₂/Ni₃O₂(OH)₄@MoS₂ core–shell nanoflower (N-NiMo-OS) in-situ grown on nickel foam (NF) (N-NiMo-OS/NF) by sulfurization treatment. Compared with the product using traditional MoG as a template, N-NiMo-OS/NF inheriting a larger core structure from N-MoG delivers enhanced space for ions transport and volume expansion during the energy storage process, together with the synergistic effects of multi-components and the heterostructure, the as-prepared N-NiMo-OS/NF nanoflower exhibits excellent performance for the battery-type hybrid supercapacitors (BHS) and ZHS devices. Notably, the ZHS device delivers superior electrochemical performance to the BHS device, such as a higher specific capacity of 327.5 mAh·g⁻¹ at 1 A·g⁻¹, a preeminent energy density of 610.6 Wh·kg⁻¹ at 1710 W·kg⁻¹, and long cycle life. The in-situ Raman, ex-situ X-ray photoelectron spectroscopy (XPS), and theoretical calculation demonstrate the extra Zn²⁺ insertion/extraction storage mechanism provides enhanced electrochemical performance for ZHS device. Therefore, the dual-ion pre-inserted strategy can be extended for other advanced electrode materials in energy storage fields.