Ideal asymmetric supercapacitors consisting of polyaniline nanofibers and graphene nanosheets with proper complementary potential windows

Microwave-assisted hydrothermal synthesis of crystalline WO3–WO3·0.5H2O mixtures for pseudocapacitors of the asymmetric type

“…0 V, for the proton intercalation/de-intercalation. Since RuO 2 ·xH 2 O nanocrystallites shows excellent capacitive performances between 0 and 1.0 V in aqueous acid media [9,10], an asymmetric EC consisting of the WO 3 -WO 3 ·0.5H 2 O anode and a RuO 2 ·xH 2 O cathode should show a working voltage of 1.6 V to enhance the energy density of this device (E = CV 2 /2 where E, C, and V indicate the energy, capacitance, and working voltage of ECs) [1,12]. Fig.…”

“…Transition metal oxides, such as crystalline hydrous ruthenium dioxide (denoted as RuO 2 ·xH 2 O) [9,10], are such a class of materials that have drawn extensive and intensive research attention in recent years. The third type is the so-called hybrid-type asymmetric ECs usually consisting of an EDLC electrode and a pseudocapacitive one [11,12], while asymmetric ECs with two pseudocapacitive electrodes have also been proposed [13][14][15].…”

Conducting polymer‐based flexible supercapacitor

“…In the past few years, it has been well demonstrated that the development of binary or ternary nanocomposites of these different capacitive materials become the novel approaches to control and optimize the structures and physical and mechanical properties of electrode materials, in order to achieve the enhanced performance for supercapacitors [76][77][78][79][80]. Various hybrid systems like MO x /CNTs [81][82][83][84][85][86][87], CPs/GO [80,[88][89][90][91][92], CPs/CNTs [93][94][95][96][97][98][99][100][101][102], and MO x /CPs [103][104][105][106] have been developed to improve the specific capacitance, stability, and energy density. However, the properties of composite electrodes depend not only upon the individual active components but also on the morphology and the interfacial characteristics.…”

Cathodic deposition of Ni(OH)2 and Co(OH)2 for asymmetric supercapacitors: Importance of the electrochemical reversibility of redox couples

“…Accordingly, the asymmetrical type consisting of two different electrode materials is designed to overcome the low cell voltage issue of symmetric ECs, especially in the aqueous system, to further promote their energy density [6,9]. Furthermore, ECs of the asymmetric type can be divided into two forms, i.e., the double-layer/redox (e.g., graphene/ polyaniline [10]) and redox/redox (e.g., RuO 2 /WO 3 [11]) types since the asymmetric design indicates that the electroactive materials in the positive electrode are different from that in the negative one. Unfortunately, significant decrease in the power density and/or cycle-life is commonly found for the asymmetric design [6,9] and how to circumvent a compromise among energy density, power density, and cycle life of asymmetric ECs is a new issue although the energy density of such next-generation ECs is expected to approach that of certain rechargeable batteries.…”