Core-shell Mn@Al-MOF: A multidimensional hierarchical advanced electrode material for high-performance supercapacitors

Multidimensional nanostructures of metal-organic frameworks (MOFs) are ideal electrode materials for supercapacitors (SCs) because of their ultrathin profiles, well-defined pores, and large surface areas. However, their self-stacking nature and weak electrical conductivity make their use challenging in various applications. In this study, hierarchical core–shell Mn@Al-MOF hybrid arrays were prepared by grafting ultrathin Al-MOF nanosheets onto rod-like Mn-MOF using a hydrothermal approach. The mesoporous Mn-MOF “core” not only provides a conductive framework for anchoring Al-MOF but also shortens ion diffusion pathways, and the Al-MOF “shell” exhibits a large active surface area. Leveraging these advantages and the synergistic effects between Al- and Mn-MOFs, the fabricated core–shell Mn@Al-MOF hybrid exhibits enhanced redox properties with a specific capacitance of 844 F/g at 1A/g. Results indicate that the MOF hybrid material primarily exhibits battery-like behavior, with diffusion contributions constituting 86 % at 1 mV/s. An innovative asymmetric hybrid design was developed by integrating the core–shell structure into a positive electrode material, achieving impressive energy density (27.26 Wh/kg) and power density (225 W/kg). In addition, this multidimensional hybrid array exhibits robust cycling stability over 10,000 charge–discharge cycles, retaining 81 % of its initial capacitance. These promising results highlight the potential of hierarchical Mn- and Al-based configurations as formidable candidates for advanced energy storage applications.