An aqueous electrolyte of the widest potential window and its superior capability for capacitors

Abstract

A saturated aqueous solution of sodium perchlorate (SSPAS) was found to be electrochemically superior, because the potential window is remarkably wide to be approximately 3.2 V in terms of a cyclic voltammetry. Such a wide potential window has never been reported in any aqueous solutions, and this finding would be of historical significance for aqueous electrolyte to overcome its weak point that the potential window is narrow. In proof of this fact, the capability of SSPAS was examined for the electrolyte of capacitors. Galvanostatic charge-discharge measurements showed that a graphite-based capacitor containing SSPAS as an electrolyte was stable within 5% deviation for the 10,000 times repetition at the operating voltage of 3.2 V without generating any gas. The SSPAS worked also as a functional electrolyte in the presence of an activated carbon and metal oxides in order to increase an energy density. Indeed, in an asymmetric capacitor containing MnO2 and Fe3O4 mixtures in the positive and negative electrodes, respectively, the energy density enlarged to be 36.3 Whkg−1, which belongs to the largest value in capacitors. Similar electrochemical behaviour was also confirmed in saturated aqueous solutions of other alkali and alkaline earth metal perchlorate salts.

Synthesis and electrolytic cation-dependent cyclic voltammetric study of SILAR deposited PPy-Cr2O3 in equimolar aqueous solutions of H2SO4, Na2SO4, and K2SO4

“…This is higher than the potential window show by pristine PPy [23,24]. Acidified water splits at − 1.23, but when it comes to aqueous solutions of salts, the potential window expands towards extremities as high as 3.2 V. The potential windows as high as 3.2 V Scheme 1 Film formation mechanism for the device have been reported for sodium perchlorate by Hiroshi Tomiyasu et al [31,32]. Hence, in the present case we got the potential window of 3 V.…”

“…Hence K + ions have higher mobility than Na + cations. The Gibbs free energy of solvation depends on the ionic radius [29][30][31]. The ionization energy of Na 2 SO 4 is 490 kJMol −1 and that of K 2 SO 4 is 418 kJMol −1 , which indicates that the ionization of K 2 SO 4 requires less energy.…”

“…PPy suffers from poor elasticity of shape, poor cycling stability, and limited potential window. To overcome these limitations, co-polymerization [31], hybridization or composite formation is going on [13][14][15][16][17][18][19][20]. Chromium has multiple oxidation states.…”

Towards High‐Performance Aqueous Sodium‐Ion Batteries: Stabilizing the Solid/Liquid Interface for NASICON‐Type Na2VTi(PO4)3 using Concentrated Electrolytes

“…[14,32,33] As ar esult, furthers tudies have been aimed at investigatingt he effect of Na-salt concentration in aqueouse lectrolytes. [35][36][37] Herein, aN ASICON-typeN a 2 VTi(PO 4 ) 3 /C (NVTP/C) composite is synthesized by as imple sol-gelm ethod and is investigated in as ymmetric aqueous Na-ion cell. In this regard, NaClO 4 is a promising candidate because it is relativelyi nexpensive, which is the reason why it is widely studied in non-aqueousN a-ion batteries.…”

“…In this regard, NaClO 4 is a promising candidate because it is relativelyi nexpensive, which is the reason why it is widely studied in non-aqueousN a-ion batteries. [35][36][37] Herein, aN ASICON-typeN a 2 VTi(PO 4 ) 3 /C (NVTP/C) composite is synthesized by as imple sol-gelm ethod and is investigated in as ymmetric aqueous Na-ion cell. The effect of the NaClO 4 concentration on the performance of NVTP/C is unraveled.I n addition, the superiore lectrochemical performance offered using 9.2 m( mol salt in kg solvent) NaCF 3 SO 3 (NaOTF) in water ("water-in-salt") as electrolyte is demonstrated.…”