MnO/C/Sepiolite 3D-network aerogel as electrode material for supercapacitors

Abstract

With the gradual increase of people's demand for energy, the energy crisis is becoming increasingly severe. A new and efficient energy storage device must be urgently exploited to relieve the pressure brought by the energy crisis. In this paper, MnO/C/Sepiolite aerogel nanocomposites were prepared by supercritical technology and freeze-drying technology as electrode materials for supercapacitors. The morphology of MnO/C aerogel is granular nanospheres, and the particle size of the calcined MnO/C aerogel ranges from 80 nm to 100 nm. Sepiolite with the unique fibrous structure can provide a matrix for MnO/C aerogel to form a stable 3D-network aerogel, and then lead to more active sites to be exposed. As results, the specific capacity of MnO/C/Sepiolite aerogel can reach 103.9 mAh/g, while the specific capacity of MnO/C aerogel is only 55.7 mAh/g at the current density of 1 A/g. Furthermore, the specific capacitance of MnO/C/Sepiolite aerogel can reach 507.4 F/g at the scan rate of 5 mV/s, higher than that of MnO/C aerogel (365.8 F/g). After 1400 cycles of repetitive charge/discharge measurement at 20 A/g current density, it is find that the specific capacitance retention rate of MnO/C/Sepiolite aerogel (98.57% retention) is higher than that of MnO/C aerogel (95.71% retention). Therefore, the problems of particle agglomeration of MnO/C active substances and low degree of active site exposure were effectively improved by the introduction of sepiolite.