Raspberry-like Ni/NiO/CoO/Mn₃O₄ hierarchical structures as novel electrode material for high-performance all-solid-state asymmetric supercapacitors

Hybrid transitional metals oxides have been attracted more and more attention in the field of supercapacitors. However, the design of structure and composition of materials is always a challenge due to tedious preparation process and difficult structure construction. Based on above issue, we construct novel raspberry-like Ni/NiO/CoO/Mn₃O₄ hierarchical structures (NNCMs) with excellent electrochemical performances by one-step hydrothermal process in this work. The introduction of metallic Ni and well-designed hierarchical structures can result in well improved conductivity for electrode material, sufficient channels and active sites for electrolyte ions to enter and contact with electrode material. The NNCMs-16 electrode exhibits a high specific capacitance of 1964 F g⁻¹ and superior cycling stability (95% of initial specific capacitance after 10000 cycles). The assembled NNCMs-16//AC device delivers outstanding energy densities of 70.4 Wh kg⁻¹ at power densities of 794.5 W kg⁻¹. Thus, the raspberry-like NNCMs-16 hierarchical structures can be regarded as promising materials for practical supercapacitors and this work also provides a valuable reference for the preparation and application of high performance electrode materials.