Study Of The Supercapacitor Based On The Cobalt Oxide Nanocomposite Material

The energy crisis, environmental deterioration, as well as the practice production and living needs make us have an urgent demand for energy-storage-device. The supercapacitor as one of the newest energy storage devices has received much attention owing to its advantages such as high power density, long service life, large capacity, wide applicable temperature, simple circuit structure, environment friendliness and so on. However, the supercapacitor also suffers from low power density and high cost. Simultaneously, the rise of mobile and wearable devices ask a higher requirement for the miniaturization and flexibility of the supercapacitor. As a result, our interest in the research and improvement of the supercapacitor will be lingering.Considering the actual demand for social needs and shortcomings of the supercapacitor, the main goal of this paper is to improve the flexibility and high-performance of the supercapacitor. The specific contents are as follows:(1) Through the handle of the shell, A honeycomb-like 3-D Carbon skeleton with a certain flexibility was achieved. Experiments showed that it was very suitable for supercapacitor. Then, a layer of CoMo04 nanorod arrays was coupled on the surface of the carbon skeleton by hydrothermal method to form a composite material. The following electrochemical tests showed that the composite material had a high specific capacity(1500F/g at 1.5A/g), good cycle performance(80% capacitace retention after 3000 cycles at 20A/g). To further explore the potential for practical applications, two all-so lid-state symmetrical supercapacitors were assembled, the electrochemical test and the experiments of lighting LED lights inferred that this was a very promising electrode materials.(2) A simple vulcanization-oxidation method was found to construct the hierarchical Co3O4 nanowire @MnO2 nanosheet arrays, namely, the transition metal oxide was firstly vulcanized by the Na2S and then oxidized by the KMnO4 not the usually time-consuming glucose assistant method. The microstructure of the MnO2 nanosheet can be controlled by adjusting the vulcanization time. By comparison, the samples after 10 minutes’ Vulcanization had the best performance (about 420F/g at 10A/g), far better than the Co3O4 nanowire arrays (167F/gat 10A/g). The outcomes proved that the vulcanization-oxidation method was a very simple, flexible and effective method to construct hierarchical structures. Considering that many kinds of oxides can be vulcanized, It is also a very universal method.(3) A simple vulcanization-oxidation-precipitation method was found to construct the Co3O4 nanowire@Co3O4 nanosheet structure, namely, the Co3O4 nanowire was firstly vulcanized with Na2S and then APS solution with a certain pH was used to obtain the hierarchical structure, it is worth noting that no cobalt source was added in the reaction process, the Co3O4 nanosheets came from the consumption of Co3O4 nanowire. Electrochemical test showed that the specific capacitance of the hierarchical Co3O4 nanowire@Co3O4 nanosheet structure was 10 times larger than the Co3O4 nanowire, about 2900F/g at a current desity of 1.5A/g. This proved that the Co3O4 nanowire@Co3O4nanosheet,arrays obtained by the vulcanization-oxidation-precipitation method has great potential applications.