Chidiac Joseph, Nikiforidis Georgios, Timperman Laure, Anouti Mérièm
Laboratoire PCM2E, Université de Tours, Parc de Grandmont, 37200, Tours, France.
Institute for Materials Discovery, University College London, Roberts Building, Malet Place, London, WC1E 7JE, UK.
Chemphyschem. 2022 Oct 6;23(19):e202200224. doi: 10.1002/cphc.202200224. Epub 2022 Jul 20.
This study reports two deep eutectic solvents (DESs) based on alkaline imide salts with asymmetric anions as functional electrolytes for supercapacitor (SC) application. The eutectic mixture of sodium (fluorosulfonyl) (trifluoromethanesulfonyl) imide (NaFTFSI) or sodium cyano-trifluoromethanesulfonyl imide (NaTFSICN) with ethylene carbonate (EC) delivers a non-flammable and stable liquid. The eutectic diagrams of the electrolytes directed to an optimal composition (w =0.25), hinging to that of conventional carbonate-based electrolytes, i. e., 1 mol L . The volumetric properties of the DESs revealed a "stacking" effect, reflecting a strong coordination bond between the imide and EC anions without solvating the Na cations. The DES transport properties (i. e., viscosity, conductivity, and ionicity) and temperature variations designate a high organization, similar to ionic liquids. The DESs, when coupled with activated carbon electrodes in a two-electrode symmetric configuration, yield specific capacities of 150 F g at a normalized current density of 0.5 A g (and 120 F g at 2 A g ). The SC maintained 80 % of its initial capacity beyond 100 h of floating at an operating voltage of 2.4 V and showed a 150 mV per hour potential loss under self-discharge. The devised eutectic mixtures offer a promising new pathway for simple, safe, and effective electrolytes for SC applications.
本研究报道了两种基于具有不对称阴离子的碱性酰亚胺盐的深共熔溶剂（DESs），作为用于超级电容器（SC）的功能性电解质。（氟磺酰基）（三氟甲磺酰基）亚胺钠（NaFTFSI）或氰基 - 三氟甲磺酰基亚胺钠（NaTFSICN）与碳酸亚乙酯（EC）的共熔混合物形成了一种不可燃且稳定的液体。电解质的共熔相图指向最佳组成（w = 0.25），这与传统的碳酸酯基电解质的组成相关，即1 mol·L 。DESs的体积性质显示出“堆积”效应，反映了酰亚胺和EC阴离子之间有强配位键，而Na阳离子未被溶剂化。DESs的传输性质（即粘度、电导率和离子性）以及温度变化表明其具有高度的有序性，类似于离子液体。当DESs与活性炭电极以两电极对称配置耦合时，在归一化电流密度为0.5 A·g 时比电容为150 F·g （在2 A·g 时为120 F·g ）。该超级电容器在2.4 V工作电压下漂浮超过100 h后仍保持其初始容量的80％，并且在自放电情况下每小时电位损失150 mV。所设计的共熔混合物为超级电容器应用提供了一种用于简单、安全且有效的电解质的有前景的新途径。
