Electrochemical Double-Layer Capacitor Containing Mixtures of Ionic Liquid, Lithium Salt, and Organic Solvent as an Electrolyte

Abstract

A modified ionic liquid (IL)-based electrolyte, with conventional carbonates as the support solvent and lithium salt as the additive, was designed for a high-voltage electrochemical double-layer capacitor (EDLC). It is found that the employment of carbonate solvents enhances the ionic conductivity and decreases the viscosity of the electrolyte. At the same time, the addition of lithium salt plays a key role in the stabilization of the operating potential window and the modification of the passivation layer on the electrode. As a result, increased specific capacitance, improved cycle stability, and rate capability are demonstrated in the EDLC with an EMI-BF4/LiPF6/PC/DMC electrolyte at the upper voltage of 3 V, in contrast to that with pure IL and IL/carbonate mixture. This study primarily stresses the combination effect of Li salt and organic solvent in an IL electrolyte system for constructing advanced 3 V-class EDLC with excellent overall performance.

In situ-fabricated quasi-solid polymer electrolytes incorporating an ionic liquid for flexible supercapacitors

“…A slight oxidation peak appeared and the peak intensity gradually increased when the upper voltage was raised from 2.8 V to 3.1 V, implying the trace amount of Faraday reaction mainly originated from electrolyte degradation. 37,38 However, the CV curves all maintained nearly rectangular shapes, representing typical electric double-layer capacitance behaviors. According to the enclosed area under the CV curve being positively related to the specic capacitance according to eqn (7) in the ESI Notes, † P2A offered a higher specic capacitance than the other cases regardless of the voltage window, in accordance with the previous charge/ discharge test results.…”

Systematic Approach to Constructing Safe and High‐Performance Supercapacitors with Nonflammable Electrolytes

“…where I (in A) represents the discharge current, m elec (in g) is the total mass loading of AC electrodes, Δ V ( in V) is the voltage window excluding the IR drop during the discharge process, and Δ t (in s) is the discharge time [15] …”

“…where I (in A) represents the discharge current, m elec (in g) is the total mass loading of AC electrodes, ΔV ( in V) is the voltage window excluding the IR drop during the discharge process, and Δt (in s) is the discharge time. [15] The energy density E (in Wh kg À 1 ) and power density P (in W kg À 1 ) of supercapacitors were determined based on the results of the GCD measurement, using the Equations ( 2) and ( 3): [14] E ¼ 1 7:2 C DV 2…”

Tuning of Ionic Liquid–Solvent Electrolytes for High-Voltage Electrochemical Double Layer Capacitors: A Review

“…The protective impact of Li + ions helped in curbing the side reactions on the AC electrode. Li et al [101] used LiFP 6 as an additive to prepare the EMImBF 4 /LiPF 6 /PC/DMC electrolyte, which had a low viscosity of 2.89 mPa s, a high ionic conductivity of 20.72 mS cm −1 , and high electrochemical stability. The inhibiting effect brought by Li + effectively hindered the reduction of cations in IL.…”