Highly conductive Mn₃O₄/MnS heterostructures building multi-shelled hollow microspheres for high-performance supercapacitors

Supercapacitors are promising energy storage devices with high power density and long cycle life, while the key challenge in the application is the fabrication of electrode materials with high surface area, good conductivity and high stability. Heterostructures consisting of binary chemical compositions could achieve superior electrochemical performances by creating abundant heterointerfaces with more reaction active sites, which could enhance the surface reaction kinetics and improve the conductivity. Meanwhile, hollow microspheres with complex internal architecture have been widely studied in advanced energy storage devices due to their high specific surface area, fast transportation of the electrolyte and prominent structural stability. Herein, we propose a feasible synthetic method of heterogeneous Mn₃O₄/MnS multi-shelled hollow microspheres. The highly conductive heterostructures as well as unique hollow multi-shelled architecture could synergistically contribute to the superior electrochemical performances. The Mn₃O₄/MnS electrode delivers a high specific capacitance of 744 F g⁻¹, excellent rate capability and cycling stability (97.7% retention after 10,000 cycles). Furthermore, an asymmetric supercapacitor with Mn₃O₄/MnS as the cathode and active carbon as the anode exhibits a high specific capacitance of 185.2 F g⁻¹ at 1 A g⁻¹, with high energy density (65.8 W h kg⁻¹) and power density (16000 W kg⁻¹). The superior electrochemical performances could be attributed to the heterostructures and the stable multi-shelled structure.