Construction of FeOOH@NiFe-LDHs heterojunction built-in more charge carriers for high energy density flexible electrode

Abstract

The same element heterojunction structure can effectively improve the energy density of the electrodes with its unique structural properties, but the specific mechanism of heterojunction action is not clear. Based on this, in this paper, the same element heterojunction electrode constructed with FeOOH on NiFe-LDHs can reach a specific capacitance of 4.34 F cm-2 at 2 mA cm-2. After 6000 cycles, its capacity is still maintained to 95.67% (30 mA cm-2). The FeOOH@NiFe-LDHs//AC flexible supercapacitor device was prepared to achieve a specific capacitance of 1.06 F cm-2 at 2 mA cm-2. More notably, an impressive energy density of 0.47 mWh cm-2 at 1.78 mW cm-2 was achieved, which is higher than previous reported. In addition, the capacitance remains 96.3% after 3000 cycles at 50 mA cm-2, and the electrode exhibited flexibility and outstanding bending stability. The high energy density of the electrodes in this study is attributed to the resulting Fermi energy level differences, which provide more carriers and increase the conductivity of the electrode material. This suggests that the heterojunction has obvious advantages for increasing the energy density of both flexible and non-flexible electrodes, and also provides new ideas for the application of supercapacitors in wearable electronic devices.