Facile and scalable fabrication of MnO2 nanocrystallines and enhanced electrochemical performance of MnO2/MoS2 inner heterojunction structure for supercapacitor application

In order to improve the production rate of MnO 2 as the excellent supercapacitor materials and enhance the performance of MnO 2 based pseudocapacitor , an innovative mechanical method of ultrasonic assisted shear exfoliation is developed to prepare MnO 2 nanocrystalline in large quantities, and then the MoS 2 composites are deposited by simple magnetron sputtering to form inner heterojunction structure to improve the overall supercapacitor performance. The electrochemical performances of the electrodes fabricated by commodity MnO 2 (c-MnO 2 ), sheared MnO 2 (s-MnO 2 ) and s-MnO 2 /MoS 2 are studied respectively. The results demonstrate that as-prepared s-MnO 2 presents better supercapacitor performance compared with c-MnO 2 due to the increase of specific surface area after the shearing process. In addition, the s-MnO 2 /MoS 2 inner heterostructure shows the best electrochemical reversibility , the highest rate capacity, the most excellent specific capacitance (~224 mF cm −2 ) and the highest conductivity among three working electrode materials because of its high specific surface area and good conductivity. The symmetrical all-solid-state supercapacitor based on s-MnO 2 /MoS 2 is fabricated, its specific capacitance can still maintain 90% after 3000 cycles of charging/discharging process, and this all-solid-state supercapacitor can power a group of 43 light-emitting diodes (LEDs). In addition, the packaged supercapacitor device can gain excellent capacitance performance during bending.