Sea urchin-shaped Fe2O3 coupled with 2D MXene nanosheets as negative electrode for high-performance asymmetric supercapacitors

Abstract Fe2O3 is one of promising negative materials for supercapacitors (SCs), because of its low cost and high theoretical value of specific capacitance. However, the inferior conductivity and insufficient ionic diffusion rate of Fe2O3 will seriously hinder the electrochemical performance of Fe2O3, resulting in limiting its practical application in SCs. Herein, a sea urchin-like 3D Fe2O3 was synthesized via hydrothermal methods. And then, the 2D Ti2C3Tx MXene nanosheets with high conductivity closely self-assemble on the surface of Fe2O3 to provide efficient pathways for the rapid electrons transport. In addition, the sea urchin-like structure of Fe2O3 can facilitate the rapid diffusion of the electrolyte to accelerate faradaic reaction. The optimized Fe2O3/MXene composite as electrode material exhibits a high specific capacitance of 486.3 F g−1 at current density of 1 A g−1, and excellent cycling stability with 95.7% capacity retention after 5000 charge/discharge cycles. Furthermore, an asymmetric supercapacitors (ASCs) device was assembled by using Fe2O3/MXene composite as anode and MnO2 as cathode, showing a high energy density of 32.2 Wh kg−1 at the power density of 900.6 W kg−1, and remarkable long-term durability (95.7 % capacitance retention after 5000 cycles). This work demonstrates an effective approach of integrating the sea urchin-like Fe2O3 with 2D MXene nanosheets to fabricate Fe2O3/MXene composite for high-performance SCs.