Non‐Flammable Sodium Asymmetric Imide Salt‐Based Deep Eutectic Solvent for Supercapacitor Applications

Abstract

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 nonflammable and stable liquid. The eutectic diagrams of the electrolytes directed to an optimal composition (w salt = 0.25), hinging to that of conventional carbonate-based electrolytes, i. e., 1 mol L À 1 . 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 À 1 at a normalized current density of 0.5 A g À 1 (and 120 F g À 1 at 2 A g À 1 ). 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.

Comparative Internal Pressure Evolution at Interfaces of Activated Carbon for Supercapacitors Containing Electrolytes Based on Linear and Cyclic Ammonium Tetrafluoroborate Salts in Acetonitrile

“…The specific capacitance stemmed from the cyclic voltammetry plots is given by the following equation [ 37,38 ] : $$\[ \begin{array}{*{20}{c}}{C\left( {F{g^{ - 1}}} \right) = \frac{{1000}}{{m \times v \times \left( {\Delta V} \right)}}\mathop \smallint \limits_{{V_ - }}^{{V_ + }} I\left( V \right)dV}\end{array} \]$$where m is the active mass on one electrode, v is the scan rate, V + denotes the cathodic potential, V − the anodic potential, and I represents the current response. The results are presented in Figure 2.…”

“…1.0 mol L −1 SPBF 4 60.0 78.2 7.56 0.72 0.54 6.90 * 6.40 [36] 0.55 0.82 −1.08 The specific capacitance stemmed from the cyclic voltammetry plots is given by the following equation [37,38] :…”

Lithium‐Ion Batteries Containing Surfactants for the Protection of Graphite Anode against the Passivation Layer Byproducts

“…Galvanostatic charge‐discharge, CV and potentiostatic impedance spectroscopy (PEIS) measurements were performed in Teflon Swagelok system [43] with controlled pressure of 0.19 N mm −2 using a Multichannel Potentiostat VMP‐3 (Biologic, France) piloted by an EC Lab V10.34 interface. The cyclic voltammetry tests were conducted by using a three‐electrode configuration comprised Graphite disk (96.25 % loading, $${\emptyset =10\hskip0.17em\hskip0.17em}$$ mm, from SAFT) as working electrode, platinum (purity>99.95 %$${,\ \emptyset =10\hskip0.17em\hskip0.17em}$$ mm, Goodfellow) or Li foil (25×100 mm, thickness: 0.6 mm, Sigma Aldrich) as a counter electrode and a Li ribbon (Sigma Aldrich) as a reference electrode was used, inserted between two polypropylene separators (thickness: 25 μm, pore diameter: 0.2–0.5 μm, Celgard).…”

Characterization of Manganese Acetate Hydrate Solutions and Their Potential Use for Energy Storage Applications

“…From Figure 5c, the electrolytes demonstrate a non-Arrhenius behaviour, i. e., the relationship is non-linear over the studied temperature range. [53] Thus, the Vogel-Fulcher-Tammann (VTF) model is applied (Equation 11) [54] adjusting temperature variations through the use of a corrective term T 0 , the ideal glass temperature. [55] The pseudo-activation energies B s a for ionic mobility extracted from the VTF model fitting, increase with higher salt concentration, yet are 15 times lower than the values obtained from alkaline salts in water (i. e., 10-15 kJ mol À 1 ).…”