The Synthesis and Characterization of Bioactive Carbon Material Supercapacitor Loaded with Nickel Hydroxide
Supercapacitor is an environmentally friendly energy storage device, which fills the gap between traditional capacitors and batteries, and its energy density and power density are higher than the battery [1]. Moreover, the supercapacitor has the characteristics of high charging and discharging efficiency and long cycle life. This makes it used in the electric vehicles, high powered weapons, standby power in electronic equipment, flash of industrial equipment and ignition device [2]. So it has great significance for the basic research, the development of electronic industry and the electric vehicle to carry out the supercapacitor electrode materials [3]. Here, we firstly prepared the activated carbon materials by carbonizing, activating the biological material, then prepared the nickel hydroxide/activated carbon composites by direct precipitation method, and studied the electrochemical properties of composite materials with different nickel hydroxide (Ni(OH)2) contents (the mass fraction). The results of cyclic voltammetry and constant current charge-discharge are that a small amount of Ni(OH)2 are mixed in the carbon surface and pores, the composite material has a good specific capacitance, stability, charging and discharging performance compared with the activated carbon. When the mass fraction of Ni(OH)2 is 12%, the supercapacitor exhibits the excellent electrochemical properties, its capacitance is up to 400.78F/g which improved 75.21% compared with the activated carbon’s capacitance (228.74F/g). 6mol/L potassium hydroxide (KOH) is used as an electrolyte, the capacitance is only reduced to 94.42% after conducting 1000 times cycle life tests. This means that the supercapacitor shows a good stability.
A comparative study of activated carbon-based symmetric supercapacitors in Li2SO4 and KOH aqueous electrolytes
In this work, we have prepared activated carbon (AC)-based symmetric supercapacitor (SC) using Li2SO4 aqueous electrolyte instead of H2SO4 and KOH and obtained a device with an improved cell voltage window (CVW) of 0 − 1.6 V from 0 to 1.0 V. The SC using KOH electrolyte is also fabricated for comparison. The electrochemical characteristics of SCs such as cyclic voltammetry (CV), galvanostatic charge–discharge, electrochemical impedance spectroscopy (EIS) and cycle stability are investigated systematically. The possible redox reactions of electrodes that occurred in Li2SO4 and KOH electrolytes that restrict the CVWs are discussed. The results indicate that in the case of Li2SO4, the AC electrode can deliver a specific capacitance of 210 F g−1 at a current density of 0.1 A g−1, and the energy density of capacitor can be as high as 16.9 Wh kg−1 at 200 W kg−1 (based on the total mass of active electrode materials), 80% higher than that in the case of KOH.
Aristocratic Century: The sinews of power: political
In his excellent book on the Secretaries of State, Mark Thomson offered ‘the paradox of continuing domination of the aristocracy and the simultaneous insignificance of the House of Lords, per se ’. It is true that, by the beginning of the eighteenth century, the supremacy of the House of Commons in financial matters was a wellestablished convention. The claims of the Commons to an undisputed control over money matters, which had been urged before the Civil War, were resumed immediately after the Restoration and a protracted dispute with the House of Lords began. In 1661 the Lords resolved that there were no precedents in history for this new claim by the House of Commons. In 1671, the Commons retorted that taxation ought not to be questioned by the Lords and in 1678 they reiterated that supply was ‘the undoubted and sole right of the Commons’ and ‘ought not to be changed or altered by the House of Lords’. The Lords' attempt in 1692 to assess their own taxes was also abandoned, though they retired under cover of a rather insubstantial smoke-screen that they maintained their power of amendment to be a ‘fundamental, inherent and undoubted right from which their lordships can never depart’. That established, they departed. Geoffrey Holmes quotes a nice example from 1702 when the bishop of Carlisle found himself the only peer answering to a money bill, ‘no other lord in the House regarded what was doing, this being only (pro forma) to preserve a seeming right to dissent from, or amend, any part of a money bill’.