Aqueous/non-aqueous electrolyte tradeoffs in charge transfer and electrochromics of pseudocapacitive oxide films. Issue 48 (1st November 2022)

• Record Type: Journal Article
• Authors: Benhaddouch, Tinsley Elizabeth; Bhansali, Shekhar; Dong, Dongmei
• Is Part Of: RSC advances. Volume 12:Issue 48(2022)
• Page Start: 31264
• Page End: 31275
• Publication Date: 2022-11-01
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d2ra05851k
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Environmental sustainability, safety, cost, and performance are the driving metrics for modern technological developments. Abstract : Environmental sustainability, safety, cost, and performance are the driving metrics for modern technological developments. Progress in these realms has been made for electrochromic (EC) devices by optimizing anode/cathode electrode materials. Yet, by these standards, the role of the electrolyte has remained unexplored. This investigation on charge transfer mechanisms at the electrolyte/electrode interface facilitates a contrast of the aqueous and non-aqueous electrolytes studied. A classic EC, high-performing, non-aqueous, lithium chlorine oxide in propylene carbonate (PC-LiClO4 ) is examined against a non-flammable, low reactive, cost-effective, aqueous, potassium hydroxide (KOH) electrolyte; to strengthen the understanding of electrochromics the electrolytes are referenced against the anodic EC nickel oxide (NiO) thin films. The KOH presents as a diffusion dominant response, supported by the findings of the cyclic voltammetry and electrochemistry impedance data ( b = 0.56, 45°∠), respectively, compared to the more surface capacitive PC-LiClO4 ( b = 0.68, 60°∠). Interestingly, despite the KOH full redox potential window being half the PC-LiClO4, the KOH system's current density reached more than 3 times higher than PC-LiClO4 . Additionally, realizing the same current density (2 mA cm −2 ) in multi-step chronoamperometry, the required potential is ∼5 times lower for KOH than for PC-LiClO4 electrolyte, albeit the KOH has a longer response time. Inherent tradeoffs in the systems are considered for theoretical analysis of these phenomena, i.e., molar mass, ionization energy, viscosity, etc. The chemical nature of the electrolyte shows a profound effect on electrochemical kinetics at the NiO/electrolyte interface, pointing to the significance of all aspects in an electrochemical cell. The coupled effect of the electrolyte composition/electrode material pairing dictates the charge-storage mechanisms (and subsequently, EC properties). Furthermore, knowledge of contrasts in electrolyte type is of great interest to the scientific community for the modern metric-based optimizations of many other clean energy systems.