Sun Xianzhong

Effects of Separator on the Electrochemical Performance of Electrical Double-Layer Capacitor and Hybrid Battery-Supercapacitor

Separators are important components in electrochemical energy storage devices such as electrical double layer capacitors (EDLCs) and hybrid battery-supercapacitors. We prepared activated carbon-based EDLCs using an electrolyte of 1 mol ∙L1 tetraethyl ammonium tetrafluoroborate (Et4NBF4) in propylene carbonate (PC), and (LiNi0.5Co0.2Mn0.3O2+activated carbon)/graphite hybrid battery-supercapacitors using a 1 mol∙L-1 lithium hexafluorophate (LiPF6) Li-ion electrolyte. The physicochemical properties and effect of various separators on the electrochemical properties of the EDLC and hybrid battery-supercapacitor were studied. The four separators were nonwoven polypropylene (PP) mat, porous PP membrane, Al2O3-coated PP membrane, and cellulose paper. The surface morphology, differential scanning calorimetry, electrolyte uptake, and apparent contact angle were investigated. The electrochemical characterizations of coin cells indicated that the EDLC with cellulose separator had the highest specific capacitance and rate capability. Differences in the selfdischarge of the four cells were not obvious. The specific capacities of the hybrid battery-supercapacitors with PP membrane and nonwoven PP mat separators were approximately 20% higher than the others. The capacitor with the cellulose paper separator had the highest self-discharge rate.

Conducting polymer hydrogel materialsfor high-performance flexible solid-state supercapacitors

Different from solid electrodes, conducting polymer hydrogel electrodes swollen with water and ions, can reach contact with the electrolyte solution at the molecular level, which will result in more efficient electrochemical process of supercapacitors. Besides, the inherent soft nature of hydrogel material offers the electrode superior flexibility, which benefits to gain high flexibility for devices. Here, this perspective briefly introduces the current research progress in the field of conducting polymer hydrogel electrodes-based flexible solid-state supercapacitor and gives an outlook on the future trend of research.Different from solid electrodes, conducting polymer hydrogel electrodes swollen with water and ions, can reach contact with the electrolyte solution at the molecular level, which will result in more efficient electrochemical process of supercapacitors. Besides, the inherent soft nature of hydrogel material offers the electrode superior flexibility, which benefits to gain high flexibility for devices. Here, this perspective briefly introduces the current research progress in the field of conducting polymer hydrogel electrodes-based flexible solid-state supercapacitor and gives an outlook on the future trend of research.摘要不同于固体电极, 导电聚合物水凝胶电极因含有大量水和离子可以使得导电聚合物与电解质实现分子层次的直接接触, 这会使得电 化学反应过程更加高效. 此外, 水凝胶内在的柔软特性, 会赋予电极优越的柔性特点, 有利于制备高柔性电子器件. 本文简要介绍了基于导 电聚合物水凝胶电极材料的柔性固态超级电容器的最新研究进展, 并对未来研究方向做了展望.

Research of supercapacitors with high energy density

Compared with traditional batteries, supercapacitors exhibit the high power density, long cycle life and wide operating temperature window. However, the relatively low energy density of supercapacitor still remains a challenge. In this paper, the structure, classification and development of supercapacitors are introduced, with an emphasis on recent work in high performance supercarpacitors of our group. The strategy for enhancement of energy density is to increase the voltage window of symmetric carbon-based supercapacitors using neutral, organic, and ionic liquid electrolytes, and adopt asymmetric supercapacitors in which one electrode is pseudocapacitive while the other utilizes double layer capacitance. Briefing is also presented on our recent investigation into hybrid supercapacitor with electrode material of lithium-ion battery/activated carbon as positive electrode, and graphite as negative electrode. This paper is ended by a perspective of future development of supercapacitors.