Nonaqueous potassium-ion hybrid capacitors (KIHCs) are faced with limited redox reaction kinetics of electrodes for accommodation of large-sized K+. Here, dipotassium terephthalate (K2TP) is applied as an organic negative electrode to provide comparable reaction kinetics with a non-faradaic activated carbon (AC) positive electrode to boost the electrochemical performance of KIHCs. It is revealed that the large exchange current density and fast two-dimensional (2D) diffusion pathways of K+ in K2TP determined by density functional theory (DFT) calculations ensure its fast redox reaction and transport kinetics. The as-constructed KIHC presents both high energy and power densities of 101 W h kg–1 and 2160 W kg–1 based on the mass of the two electrodes (41.5 W h kg–1 and 885.2 W kg–1 based on the mass of the two electrodes and electrolyte), respectively, and a superior capacity retention of 97.7% after 500 cycles. The excellent electrochemical performance is attributed to the fast kinetics, good structural flexibility, and small volume change (9.4%) of K2TP upon K+ insertion/extraction, and its good compatibility with the AC positive electrode in 1,2-dimethoxyethane (DME)-based electrolyte. This will promote application of organic materials in hybrid capacitors and the development of KIHCs.
展开▼
机译:非水钾离子混合电容器(KIHC)面临电极的氧化还原反应动力学的限制,无法容纳大尺寸的K + sup>。在此,将对苯二甲酸二钾(K2TP)用作有机负极,以提供与非法拉第活性炭(AC)正极相当的反应动力学,从而增强KIHC的电化学性能。结果表明,通过密度泛函理论(DFT)计算确定的K2TP中K + sup>的大交换电流密度和快速二维(2D)扩散路径确保了其快速的氧化还原反应和传输动力学。构造后的KIHC的高能量和功率密度基于两个电极的质量(41.5 W,分别为101 W h kg -1 sup>和2160 W kg -1 sup>)基于两个电极和电解质的质量分别为h kg –1 sup>和885.2 W kg –1 sup>,在500次循环后,其卓越的容量保持率为97.7%。优异的电化学性能归因于K + sup>插入/提取时K2TP的快速动力学,良好的结构柔韧性和小体积变化(9.4%),以及与1号AC正极的良好相容性,2-二甲氧基乙烷(DME)基电解质。这将促进有机材料在混合电容器中的应用以及KIHC的发展。
展开▼