With sea urchin sodium titanate as the negative pole and porous activated graphene as the positive pole, what kind of “spark” will be generated when they combine? According to the dalian Institute of Chemical Physics, Chinese Academy of Sciences, wu Zhongshuai’s team and Bao Xinhe’s team worked together to combine “sea urchins” with graphene to develop flexible sodium ion micro-supercapacitors with high energy density and high heat resistance.
Micro miniature sensors, micro robot, the power supply system is inseparable from the micro electrochemical energy storage devices, such as the device is mainly refers to the kind of electrode size in microns within the scope of the miniaturization of power supply, is considered to be flexible, miniaturization, intelligent integrated key power electronic products, mainly divided into micro battery and a super capacitor, as well as the trend in recent years hybrid miniature super capacitor.
It is reported that the micro cell has high energy density but low power density. Micro supercapacitors have high power density but low energy density. Hybrid micro supercapacitors combine the advantages of high energy density of micro batteries and high power density of micro supercapacitors, and become a new type of micro electrochemical energy storage devices, among which lithium ion micro supercapacitors are more representative.
Lithium ion micro supercapacitor has high energy density and power density, but its large-scale application is limited by the resource limitation of metal lithium and high development cost (the crustal abundance of lithium is 0.006%). On the contrary, the crust of sodium is rich in resources, accounting for 2.74%. Its development cost is relatively low, and its electrochemical performance is similar to that of lithium. Therefore, the development of sodium ion micro-supercapacitor has an important application prospect.
The research and development team of Dalian Chemical Research Institute of Chinese Academy of Sciences successfully constructed a flexible sodium ion micro supercapacitor by using sea urchin sodium titanate as the negative electrode of the battery type, porous activated graphene as the positive electrode of the capacitive type, and combined with the high-pressure ionic liquid gel electrolyte. By effectively coupling the battery-type negative electrode to the capacitive positive electrode, they enabled the sodium supercapacitor to operate stably at 3.5 volts, with a high energy density of 37.1 MWH/cM3, and an ultra-low self-discharge rate.
According to the researchers, the sodium ion micro supercapacitor has multi-directional fast ion diffusion channels, which greatly reduces the charge transfer resistance and significantly improves the power density. At the same time, due to the planar geometry of the device and the incombustibility of the ionic gel electrolyte, the device has good mechanical flexibility and high temperature stability of 80℃.
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