Atomic surface regulated nanoarchitectured MnCo2S4@ALD-CoOx positrode with rich redox active sites for high-performance supercapacitors

Multi-metal sulfide nanoarchitecture materials can enhance the performance of supercapacitors by increasing the redox active sites and surface reaction kinetics via the facilitation of more ions/electron pathways. The surface morphologies and developing technology of nanoarchitecture materials significantly affect the electrochemical performance of electrode materials. Therefore, this study deposits an atomic layer of CoOx on MnCo2S4 nano-needles to develop a potential positrode that can deliver outstanding electrochemical behavior and cycle per-formance characteristics. The MnCo2S4 nanoneedles are fabricated using a two-step hydrothermal-sulfidation method. Results reveal that the atomic layering of 10-nm CoOx on the surface of MnCo2S4 nanoneedles enhances the specific capacity (to 628C/g (1396F/g)) at a current density of 3 A/g compared to those of pristine MnCo2S4 and other atomic layer-deposited materials owing to the low charge transfer resistance and high surface active sites of the optimized material. Furthermore, an asymmetric supercapacitor device is fabricated using the 10-nm CoOx atomic-layered MnCo2S4 as the positrode, and activated carbon as the negatrode. The fabricated device delivers a maximum energy density of 78.67 Wh/kg at a power density of 847 W/kg and stable 8000 char-ge-discharge cycles at a current density of 5 A/g. The improvement in the electrochemical performance can be attributed to the combined contribution of both components (i.e., atomically-layered CoOx and unique core-shell nanoarchitecture).