Research On The Fabrication Of Silicon And Carbon Micro/Nanostructures For Microsupercapacitor Electrodes

Microsupercapacitor is a new type of energy storage device with power density and energy density between capacitors and batteries.It is widely concerned due to its excellent cycling performance and high power.This paper introduces a variety of micro/nanostructures for microsupercapacitor and studies the electrochemical performances of the micro/nanostructures as microsupercapacitor electrodes.The main content and innovation point of this paper are summarized as below.（1）A novel facile and low-cost fabrication method based on nanopitting and wet chemical etching for preparing uniform silicon micro/nanostructures is proposed.Silicon micro-pyramid structures were formed on the surface of single crystal silicon by KOH anisotropic etching,and silicon nanowires with uniform distribution were processed on the surface of the silicon micro-pyramid structures by the combination of nanopitting and metal-assisted chemical etching.Together with wet chemical etching,uniformly distributed silicon micro/nanostructures were obtained.The silicon micro/nanostructures with different morphology were obtained by controlling the thickness of silver nanofilm,pitting time and metal-assisted chemical etching time.Finally,MnO₂ active materials were deposited on the surface of silicon microstructures and silicon micro/nanostructures to obtain microsupercapacitor electrodes,respectively.And the silicon micro/nanostructures were proved to have better electrochemical performance by comparison.（2）A new fabrication method based on oxygen plasma etching and C-MEMS for preparing carbon micro/nanostructures on the stainless steel substrate is proposed.The SU-8 photoresist microstructures with high aspect ratio were fabricated by photolithography on 310S stainless steel substrate.The photoresist micro/nanostructures were obtained by the oxygen plasma etching method,and the fabrication of carbon micro/nanostructures were further realized by the pyrolysis process.The carbon micro/nanostructures with different morphologies were obtained by controlling the thickness of photoresist and etching time,and the influences of photoresist thickness and etching time on the morphology of carbon micro/nanostructure were explored.Finally,the electrochemical performance of the carbon microstructure and the carbon micro/nanostructures were tested.And the carbon micro/nanostructures which have higher surface area show larger electrochemical performance than that of carbon microstructures.（3）The C/MnO₂ composite microsupercapacitor electrodes were obtained by depositing MnO₂ active material on the surface of the carbon micro/nanostructures.The influence of the different deposition time of MnO₂ active materials on the carbon micro/nanostructures was explored.The C/MnO₂ composite microsupercapacitor electrodes shows excellent capacitance performance,due to the decoration of MnO₂ active materials increasing the electrochemical active sites for the redox reaction.The C/MnO₂ composite microsupercapacitor electrodes with5 min MnO₂ deposition shows the specific gravimetric capacitance of 453.47 F g^-1 at the current density of 0.05 mA cm^-2.And the capacitance of the microsupercapacitor electrodes still remains94.01%of its initial value after 6000 cycles at the current density of 1 mA cm^-2,performing excellent long-term cycling stability.