Development of hierarchically structured nanosheet arrays of CuMnO₂-Mn_xO_y@graphene foam as a nanohybrid electrode material for high-performance asymmetric supercapacitor

Transition-metal-based nanomaterials are preferred for electrochemcial supercapacitor applications owing to their low purchasing cost, facile synthesis process and high theoretical electrochemcial performance. However, these materials can not translate their excellent theoretical performance into commendable experimental values. In these circumstances, supercapacitors based on new class of highly conductive and electroactive hybrid nanomaterial are recommended. Herein, for the first time, 2D CuMnO₂-Mn_xO_y@graphene foam (GF) hybrid nanomaterial is constructed as a novel electrode material for asymmetric supercapacitor application. The CuMnO₂-Mn_xO_y@GF hybrid nanomaterial displays an excellent areal capacitance of 7.82 F cm⁻² at a current density value of 3 mA cm⁻²_, while it also maintains maximum areal capacitance of 67.51% at 60 mA cm⁻². The CuMnO₂-Mn_xO_y@GF hybrid nanomaterial retains a high capacitance of 92.15% after maximum 10,000 cycles. A high-performance asymmetric supercapacitor device is assembled based on CuMnO₂-Mn_xO_y @GF and sulfur-nitrogen-codoped graphene nanosheets (SN-GNs) as positive and negative electrode materials, respectively. The CuMnO₂-Mn_xO_y @GF//SN-GNs ASC device shows an ultra-high energy density value of 81.4 W h kg⁻¹ at a minimum power density of 809.5 W kg⁻¹. The CuMnO₂-Mn_xO_y @GF//SN-GNs ASC device retains a specific capacitance of 88.88% after 10,000 cycles. The CuMnO₂-Mn_xO_y@GF hybrid nanomaterial is beneficial to promote asymmetric supercapacitor device with an excellent electrochemcial performance.