Highly stable 2,3,5,6-tetrachloro-1,4-benzoquinone electrodes for supercapacitors

Carbon materials have enjoyed wide applications in supercapacitors because of their high surface area which guarantees a high power output through the formation of an electric double layer (EDL). However the energy stored by this EDL mechanism is often insufficient and as such there is the need to upgrade them for higher energy applications. Quinone materials are attracting interest because of their pseudocapacitance contributions which help to boost the energy density of supercapacitors. In this study, composite supercapacitor electrodes are prepared by mechanically mixing 2,3,5,6-tetrachloro-1,4-benzoquinone (TCBQ) and activated carbon. An investigation of 5% w/w and 10% w/w of this quinolic material as a pseudocapacitance material to activated carbon in 1 M HCl aqueous electrolyte delivers a specific capacitance of 236 F g−1 and 240 F g−1 comparable to 190 F g−1 of just activated carbon over a potential range of −0.3 V–0.9 V vs Ag+/Ag. Contrary to what is commonly observed, this material is highly insoluble in the electrolyte medium and remains stable with cycling, recovering 99.57% (for 10% w/w addition) and 99.13% (for 5% w/w addition) of its initial capacitance after cycling at 500 mV s−1 scan rate. The findings in this report potentially provides a cheaper yet efficient route to boost the energy density of activated carbon using TCBQ for high energy supercapacitor applications. © 2017 Elsevier B.V.1

Structural Effect of Conductive Carbons on the Adhesion and Electrochemical Behavior of LiNi0.4Mn0.4Co0.2 O(2 )Cathode for Lithium Ion Batteries

The adhesion strength as well as the electrochemical properties of LiNi0.4Mn0.4Co0.2O2 electrodes containing various conductive carbons (CC) such as fiber-like carbon, vapor-grown carbon fiber, carbon nanotubes, particle-like carbon, Super P, and Ketjen black is compared. The morphological properties is investigated using scanning electron microscope to reveal the interaction between the different CC and the active material. The surface and interfacial cutting analysis system is also used to measure the adhesion strength between the aluminum current collector and the composite film, and the adhesion strength between the active material and the CC of the electrodes. The results obtained from the measured adhesion strength points to the fact that the structure and the particle size of CC additives have tremendous influence on the binding property of the composite electrodes, and this in turn affects the electrochemical property of the configured electrodes. © 2018, Korean Electrochemical Society. All rights reserved.1

EMI-BF4 electrolyte and Al2O3/PVDF-HFP modified PE separator for high capacitance retention and cycle stability in supercapacitors

Polyolefin separators are inherently hydrophobic and thermally unstable, contributing to poor cycle performance and high thermal shrinkage, respectively, which can shorten cycle life. Herein, a high-performance supercapacitor based on a composite separator made from nano-Al2O3/PVDF-coated on polyethylene (PE) polyolefin substrate was prepared using a low-cost casting (stir-dip-coat-dry) technique and an electrolyte containing 1M EMI-BF4 salt in EC : EMC:DMC (1 : 1 : 2 vol%) is reported. The results show that integration of nano-Al2O3 in the PVDF matrix contributes to a large interactive surface area that attenuates interfacial energy at the separator-electrolyte boundary and improves porosity as well as the overall performance. The filler also enhances high mechanical anchoring onto the PE substrate, contributing to the overall physical and electrochemical properties of the separator. These modified PE separators with porous microstructure demonstrate superior electrolyte wettability (88%), stable electrochemical performance, and high cycle stability superior to analogous cells with commercial separators. The pair of coated modified separators with the 1M EMI-BF4 modified electrolyte registered a high ionic conductivity value of 2.23mS/cm. This facile technique is scalable for separator-electrolyte design and is attractive for low-cost supercapacitor manufacturing which is safe and fast charging.FALS