Zhu Xuebin, professor of Functional Materials Physics and Devices, Institute of Solid State Physics, Hefei Institute of Physical Science, Chinese Academy of Sciences, has recently made progress in the research of vanadium nitride (VN) supercapacitor materials. The researchers prepared porous VN films on silicon substrates by solution method, which showed excellent supercapacitor performance. Relevant research results show that Solution-processable hierarchical-porous vanadium nitride films on Silicon substrates for highly efficient Symmetric supercapacitors, published in The Journal of Power Sources.
VN is an excellent electrode material for supercapacitors with excellent conductivity, large voltage window and high theoretical specific capacitance. VN supercapacitor thin film electrode can be fabricated directly on silicon substrate to construct micro supercapacitor device unit, which is expected to be applied in chip electronic device and portable electronic device. At present, most VN thin film electrodes are prepared by physical method, which is not only difficult to effectively control the morphology of the film, but also limits the performance improvement of VN thin film.
In this study, the researchers successfully prepared large-size, multistage porous VN films on silicon substrates by chemical solution method, which can effectively improve ion and electron transport, thus improving the performance. The results show that the film can reach an area ratio capacitance of 60 mF cm-2 in 1M KOH electrode liquid. The symmetrical solid state supercapacitor based on the thin film has high energy density and power density, excellent cycle stability, and can effectively widen the voltage window through the device series, and then drive different color LED lamps.
This work provides a new idea for the realization of low-cost, high-performance electrode materials suitable for micro supercapacitors. The research work was supported by the National Key RESEARCH and development Program and the National Natural Science Foundation of China.
Figure 1. Sem results of (a) plane low magnification, (b) plane high magnification, and (c) cross section high magnification of porous VN films
Figure 2. Performance tests of symmetric solid state supercapacitors :(a) capacitance-voltage results at 100 mV s-1 sweep speed of series devices, (b) charge-discharge results at 1.0 mA cm-2 current density of series devices, (c-e) physical pictures of series devices driving different color LED lights
Source: Hefei Institutes of Physical Science, Chinese Academy of Sciences