Synergistic effect of Co3O4@C@MnO2 nanowire heterostructures for high-performance asymmetry supercapacitor with long cycle life

Heterostructures show excellent performance in energy and environment fields due to the unique interface structure and synergistic effect of multi-components. Here, we introduce a stepwise method to prepare multi-element Co3O4@C@MnO2 heterostructures on nickel foam as binder-free supercapacitor electrode material, where crystalline Co3O4 acts as intimal “core” and wrinkled ultrathin MnO2 nanosheets as the outer “shell”. In three-electrode mode, Co3O4@C@MnO2 shows excellent electrochemical performance with a high cyclic specific capacitance of 1335.3 F g−1 at a current density of 20 A g−1. Furthermore, the asymmetry supercapacitor device assembled with Co3O4@C@MnO2 heterostructures and active carbon exhibits high specific capacity (126.6 F g−1 at a current density of 0.5 A g−1) and long life (about 61 F g−1 at a relatively high current of 20 A g−1 after 40,000 cycles). Compared with Co3O4@MnO2 or C@MnO2, the improved performance of Co3O4@C@MnO2 heterostructures is proposed to be attributed to the synergistic effect in multi-components. Remarkably, the introduction of C between Co3O4 and MnO2 could promote the electron transfer, reduce the impedance and thus improve the electrochemical performance of the heterostructures.