Recently, Wu Zhongshuai, doctoral supervisor of the University of Chinese Academy of Sciences and researcher team of two-dimensional materials chemistry and energy application research group (508 groups) of State Key Laboratory of catalysis, Dalian Institute of Chemical Physics, developed a high voltage potassium ion micro supercapacitor based on MXene derived potassium titanate anode material and built an integrated microsystem of micro supercapacitor pressure sensor Unification.
In order to adapt to the rapid development of flexible, wearable, and implantable microelectronics, it is necessary to develop micro-energy storage devices with high performance, mechanical stability, and high compatibility. The micro supercapacitor has great potential in the field of microelectronics due to its high power density, fast charge-discharge rate, and long life. However, there are still some problems such as low energy density and narrow potential window. Hybrid metal ion micro supercapacitor combines the advantages of battery type negative electrode and supercapacitor type positive electrode, which can achieve high energy density and high power density at the same time. Among many metal ions, potassium is abundant and its reduction potential is low (- 2.93 V) vs.SHE ）。 In addition, the weak solvation effect and small Stokes radius of potassium ions in non-aqueous electrolytes contribute to the improvement of potassium ion transfer number and ionic conductivity. However, there are still challenges in the design of key materials and devices for K + micro-supercapacitors.
In this work, the team developed a strategy of simultaneous oxidation and alkalization of MXene (Ti3C2) to prepare novel potassium titanate nanorods with large aspect ratio and ion diffusion coefficient, as well as high potassium storage capacity (145mah / g). With potassium titanate as the negative electrode and living graphene as the cathode, the new type of potassium ion micro supercapacitor is constructed with high voltage ionic liquid gel electrolyte. It has a high voltage window of 3.8V, which is superior to the previously reported micro supercapacitor. Due to the main contribution of pseudocapacitance and the small change of electrode volume during charging and discharging, the potassium ion micro supercapacitor has excellent rate performance and cycling performance, and the bulk energy density reaches 34.1mwh/cm3. In addition, the potassium ion micro supercapacitor is compatible with the pressure sensor on the same flexible substrate, which can sensitively monitor body movement. This work not only provides a new idea for the design of high-performance micro supercapacitor but also provides an example for the flexible electronic devices powered by the micro supercapacitor.
The related research results were published in advanced energy materials entitled "high voltage potassium ion micro-supercapacitors with external volumetric energy density for wearable pressure sensor system". The first author of this work is Zheng shuanghao, associate researcher of group 508 of Dalian Institute of Chemical Physics, and Ma Jiaxin, a doctoral candidate. The above work is supported by the National Natural Science Foundation of China, the national key R & D program, the cooperation fund of Clean Energy Innovation Research Institute of Chinese Academy of Sciences, and the central and local special projects of Liaoning Province.