An evaluation of the capacitive behavior of supercapacitors as a function of the radius of cations using simulations with a constant potential method.

We report on the molecular dynamics atomistic applying the constant potential method to determine the structural and electrostatic interactions at the electrode-electrolyte interface of electrochemical supercapacitors as a function of...

Improved Capacitive Behavior of Birnessite Type Mn Oxide Coated on Activated Carbon Fibers

Birnessite type Mn oxide (potassium birnessite hydrate) powder (as-δ-MnO2) with a layered microstructure was prepared via a hydrothermal process. To improve its capacitive performance, the microstructure was thermally modified (annealed) at 400 oC (400-δ-MnO2) in a N2 reducing environment. By removing the hydrated cations (K+) layers inserted between the main layers of birnessite, damaging the microstructure, intercalation/deintercalation of the electrolyte species (Li+1) became more effective. Characterization of as-δ-MnO2 and 400-δ-MnO2 revealed that no phase transformation occurred during the annealing process. The microstructure became less crystalline and the total pore volume increased from 0.20 cm3 g-1 to 0.43 cm3 g-1, while the oxidation state of Mn remained 4+ after annealing the as-δ-MnO2 at 400 oC. The 400-δ-MnO2 sample was then coated on asphaltene derived activated carbon fibers (ACF-400-δ-MnO2) to improve the performance by making use of the high electrical conductivity and capacitive behavior of ACF. Coating the 400-δ-MnO2 sample led to a significant increase in the capacitance (328 F g-1 and 195 F g-1 for ACF-400-δ-MnO2 and 400-δ-MnO2 at 0.4 A g-1, respectively), improved energy and power values (~7 kW kg-1 at ~4.2 Wh kg-1 for ACF-400-δ-MnO2 and 240 W kg-1 at 2.4 Wh kg-1 for 400-δ-MnO2) and improved cycling behavior.

Nano and Battery Anode: A Review

Improving the anode properties, including increasing its capacity, is one of the basic necessities to improve battery performance. In this paper, high-capacity anodes with alloy performance are introduced, then the problem of fragmentation of these anodes and its effect during the cyclic life is stated. Then, the effect of reducing the size to the nanoscale in solving the problem of fragmentation and improving the properties is discussed, and finally the various forms of nanomaterials are examined. In this paper, electrode reduction in the anode, which is a nanoscale phenomenon, is described. The negative effects of this phenomenon on alloy anodes are expressed and how to eliminate these negative effects by preparing suitable nanostructures will be discussed. Also, the anodes of the titanium oxide family are introduced and the effects of Nano on the performance improvement of these anodes are expressed, and finally, the quasi-capacitive behavior, which is specific to Nano, will be introduced. Finally, the third type of anodes, exchange anodes, is introduced and their function is expressed. The effect of Nano on the reversibility of these anodes is mentioned. The advantages of nanotechnology for these electrodes are described. In this paper, it is found that nanotechnology, in addition to the common effects such as reducing the penetration distance and modulating the stress, also creates other interesting effects in this type of anode, such as capacitive quasi-capacitance, changing storage mechanism and lower volume change.

Capacitive behavior of functionalized activated carbon-based all-solid-state supercapacitor

In this report, we incorporate activated carbon (AC) onto aluminum substrate via doctor blade method to produce an all-solid-state supercapacitor. The electrochemical properties of the all-solid-state supercapacitor were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Galvanostatic charge/discharge tests also were carried out to exhibit stability of the AC-based supercapacitor. The impedance and charge/discharge curves of the all-solid-state supercapacitor showed good capacitive behavior after functionalized AC. The highest specific capacitance obtained for the AC-based supercapacitor was 106 F g−1. About 160% of specific capacitance increased after functionalization of the AC, which indicated that modification of the AC by nitric acid was able to introduce functional groups on the AC and improve its electrochemical performances.

Enhanced electrochemical performances of activated carbon (AC)-nickel-metal organic framework (SIFSIX-3-Ni) composite and ion-gel electrolyte based supercapacitor

In this study, we investigated that the activated carbon (AC)-based supercapacitor and introduced SIFSIX-3-Ni as a porous conducting additive to increase its electrochemical performances of AC/SIFSIX-3-Ni composite-based supercapacitor. The AC/SIFSIX-3-Ni composites are coated onto the aluminum substrate using the doctor blade method and conducted an ion-gel electrolyte to produce a symmetrical supercapacitor. The electrochemical properties of the AC/SIFSIX-3-Ni composite-based supercapacitor are evaluated through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge/discharge tests (GCD). The AC/SIFSIX-3-Ni composite-based supercapacitor showed reasonable capacitive behavior in various electrochemical measurements, including CV, EIS, and GCD. The highest specific capacitance of the AC/SIFSIX-3-Ni composite-based supercapacitor was 129 F g−1 at 20 mV s−1.

Why conductivity is not always king – physical properties governing the capacitance of 2-D Metal-Organic Framework - based EDLC supercapacitor electrodes: Ni3(HITP)2 as a case study

We report a systematic study on the variation of physical properties of Ni3(HITP)2 (HITP = 2,3,6,7,10,11-hexeaiminotriphenylene) in the context of their influence on the capacitive behavior of this material in...

In situ hydrothermal synthesis of nickel cobalt sulfide nanoparticles embedded on nitrogen and sulfur dual doped graphene for a high performance supercapacitor electrode

Newly developed in situ hydrothermal synthesis governs morphology of Ni–Co–S embedded on N–S doped graphene thus providing exceptional capacitive behavior.