scholarly journals SYNTHESIS AND CHARACTERIZATION OF CHITOSAN/SODIUM ALGINATE BLEND MEMBRANE FOR APPLICATION IN AN ELECTROCHEMICAL CAPACITOR

2020 ◽  
Vol XXV ◽  
pp. 174-191
Author(s):  
Krzysztof Nowacki ◽  
Maciej Galiński ◽  
Izabela Stępniak
Keyword(s):  
Solid Electrolyte ◽  
Sodium Alginate ◽  
Polyelectrolyte Complex ◽  
Electrochemical Impedance ◽  
Electrochemical Capacitor ◽  
Double Layer Capacitor ◽  
Formation Method ◽  
Electrochemical Double Layer ◽  
Stepwise Formation

In this work, we report a stepwise formation method of a chitosan/sodium alginate polyelectrolyte complex (CS/SA PEC) membrane. The proposed method aiming at the utilization of the ultrasonic treatment of chitosan and sodium alginate solution allowed us to obtain a highly homogeneous hybrid membrane for electrochemical usage. The CS/SA PEC membrane saturated in a 2 M Li2SO4 aqueous solution was used in electrochemical double layer capacitor (EDLC) cell to study its applicability as quasi-solid electrolyte. Electrochemical characteristic of EDLC cells was determined by electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge/discharge methods. The results show that the EDLC cell with CS/SA PEC quasi-solid electrolyte exhibit a comparable specific capacitance (102 F g-1 for 0–0.8 V) to CS reference (100 F g-1 for 0–0.8 V) and commercial separator (99 F g-1 for 0–0.8 V) cells. Thus, the CS/SA PEC membrane can be considered as an alternative modification for chitosanbased materials of electrochemical purpose.

Highly Concentrated Aqueous Electrolyte With a Large Stable Potential Window for Electrochemical Double-Layer Capacitors

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Guoqing Zhang ◽  
Yongqing Zhao ◽  
Binbin Jin ◽  
Peng Zhang ◽  
Shuying Kong
Keyword(s):  
Aqueous Electrolyte ◽  
Electrochemical Impedance ◽  
Discharge Rate ◽  
Saturated Calomel Electrode ◽  
Electrochemical Capacitor ◽  
Superior Performance ◽  
Operating Voltage ◽  
Galvanostatic Discharge ◽  
Electrochemical Double Layer Capacitors ◽  
Electrochemical Double Layer

Abstract An active carbon (AC)/AC electrochemical capacitor, taking advantage of a high-concentrated lithium trifluoromethane sulfonate (LiTFS) or lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) aqueous electrolyte, was demonstrated with an extended operating voltage of 2.5 V, which is the largest value till now for aqueous carbon-based capacitors. The AC electrode is entirely capacitive in these two electrolytes and the stable potential window of the single AC electrode can reach −1.2 to 1.2 V versus the saturated calomel electrode (SCE). The performance of the AC-based capacitor is evaluated in two- and three-electrode cells using a combination of electrochemical impedance (EIS), cyclic voltammetry (CV), galvanostatic discharge-charge, and self-discharge (SD, i.e., leakage current) measurements. At 0.5-mA cm−2 charge-discharge rate, the AC/AC capacitor presents 5.5 wh kg−1 and 4.5 wh kg−1 energy density for 20 m LiTFS and LiTFSI electrolyte, respectively. The results suggest that a thorough utilization of such lithium salt aqueous electrolytes with widening electrochemical stable potential window will no doubt lead to further development of electrochemical capacitors toward superior performance.

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