Three-dimensional Supercapacitors Based On Macroporous Electrically Conductive Network (MECN)

In recent years, with the great progress has been made in MEMS technology, and compared with the normal three-dimensional materials, the MEMS-based three-dimensional structure of the silicon material with high compatibility, unique chemical and physical properties increasingly become the research hotspot of scholars from various countries. Because of the excellent properties of the multifaceted silicon microchannel plate, making it an ideal substrate material for new micro energy devices and electrochemical sensors. In this paper, the silicon micro-channel plate (Si-MCP) prepared by the electrochemical etching as the substrate material, a series of innovative research work has been carried out as the novel three-dimensional supercapacitors:Firstly, the ordered macroporous channel arrays-the silicon micro-channel plate (Si-MCPs) which has a large specific surface area and aspect ratio was fabricated by the 4 inches silicon process line based on MEMS technology. After the process of chemical deposition a nickel layer on surface and porous of Si-MCP, the nickel covered three-dimensional structure of macroporous electrically conductive network (MECN) was created which provides the basic framework for various supercapacitors. The thin film of Co(OH)2 nanoflacke was fabricated on the surface and porous of MECN by the electrodeposition method. The manufactured Co(OH)2/MECN samples have a different nanostructures with the change of electrodeposition solution and the best sample has a large surface capacitance of 6.9F cm-2 with a good cycling ability. The deposition time of Co(OH)2 on the MECN has a great influence on the performance of the electrode and using a suitable deposition time of 6 min, the electrode has a good electrochemical characteristics; packaged the Co(OH)z/MECN electrode with deposition time of 6 min as a cathode electrode andthe graphite mixture materials as the negative electrode together as the asymmetric supercapacitor into a standard CR2025 battery shell with the quasi-solid KOH electrolyte. Secondly, preparation and study the CO3O4 nanostructures faraday supercapacitor electrode material that fabricate by the high temperaturethermal annealing Co(OH)2/MECN in a vacuum environment at 300℃ for 2h. The annealed samples were characterized by SEM, XPS, XRD and electrochemical tested including different scanning speeds of cyclic voltammetry, charge-discharge with different current density,2000 cycles large current charge-discharge, impedance spectroscopy tests before and after the 2000 cycles test.The active materials were fabricate on the surface of MECN by electrodeposition Ni(OH)2-Co(OH)2 in the mixed electrolyte contain both Ni2+ and Co2+ to improve the capacitance of the device. After a series of experiments to the verification the electrochemical characterize of our samples, the results show that the Ni(OH)2-Co(OH)2 with a ratio of 10:1 has a better capacity and stability.Excessive Ni(OH)2 would reduce cycle performance of the device, while too much Co(OH)2 reduced the specific capacity the device significantly.Finally, the preparation and study the novel CoMoO4 nanostructures faraday supercapacitor electrode material based on MECN was also introduced in this paper which has a highly ordered structure, strong electrochemical activity. The specific capacitance (area capacitance) reach to 667.11F g-1 (5.07F cm-2) at the current density of 2mA cm-2, the capacity retention of the sample after 5000 cycling can reach to 85.98% at a high charge-discharge current density. After package the CoMoO4/MECN electrode as the cathode electrode in a CR2025 battery shell, three of such supercapacitors in series can simultaneously lit two 5mm LED several minutes. The activate full supercapacitor has 71.82% capacity keeping after charge-discharge 5000 cycles under a large current density.In summary, the core of this paper is combined silicon microchannel plate based on MEMS technology and supercapacitor integrate through the technology of semiconductor materials, energy storage devices, nano-science that provide new ideas and research directions. As well as opening a new way of integrated circuit technology with the energy storage devices and provided a new approach of silicon micro-channel plate for practical application. This article will further promote mutual development among the MEMS technology, the semiconductor industry and new energy.