FeMn-LDH/Ni(OH)2 with unique flower-like heterostructure as electrode material for supercapacitor
摘要
The heterostructure of electrode materials can improve conductivity and ion transport efficiency, thereby enhanced capacitance performance. In this study, we prepared FeMn-LDH by a hydrothermal method and then obtained FeMn-LDH/Ni(OH)2 with a flower-like heterostructure by electrodeposition. This unique heterostructure greatly improves the electrochemical properties of the electrode material, which exhibits a specific capacitance of 2380.5 F g−1 at a current density of 1 A g−1, much higher than that of FeMn-LDH (1109.5 F g−1). Even at a current density of 20 A g−1, the specific capacitance of FeMn-LDH/Ni(OH)2 can still reach 1660 F g−1 with a capacitance retention of 69.9%, which is better than that of FeMn-LDH (46.2%). We then assembled FeMn-LDH/Ni(OH)2 with activated carbon (AC) to form a capacitor. The excellent energy density (49.7 Wh kg−1) and power density (750 W kg−1) proves the potential application of FeMn-LDH/Ni(OH)2. The cycling stability of capacitors is remarkably good, after 10000 cycles, its capacitance still remains 79%. Furthermore, we conducted energy band and density of states (DOS) calculations for FeMn-LDH and FeMn-LDH/Ni(OH)2. The results indicated that the inclusion of Ni(OH)2 enhanced the conductivity of the FeMn-LDH/Ni(OH)2 materials by boosting the transmission of electrons near the Fermi energy level.