The Influence of Dimethyl Sulfoxide as Electrolyte Additive on Anodic Dissolution of Alkaline Zinc-Air Flow Battery

Abstract

The present work describes the effects of dimethyl sulfoxide (DMSO) in KOH aqueous electrolyte on the performance of a zinc-air flow battery. Aqueous electrolytes containing 7 M KOH and (0 to 20)% v/v DMSO were studied revealing a critical role of DMSO on the dissolution and deposition of zinc. The anodic zinc dissolution process was studied via cyclic voltammetry, Tafel polarization and electrochemical impedance spectroscopy (EIS). The presence of DMSO showed improved zinc dissolution performance with the highest peak of zinc dissolution being the electrolyte containing 5% v/v DMSO. Tafel analysis demonstrated a significant decrease in polarization resistance and an increase in corrosion rate due to the introduction of DMSO to the electrolyte. This suggests that DMSO has the ability to suspend zinc oxide in the electrolyte, thus preventing passivation of the zinc surface. EIS results revealed that by adding DMSO to the electrolyte, charge transfer resistance increased. This is attributed to the formation of passive layers having arisen from DMSO adsorption, the formation of zincate ions in the vicinity of the zinc surface, and the deposition of discharged products. A difference in Nyquist plots was observed for 20% v/v DMSO/KOH and 0% v/v DMSO/KOH electrolytes implying non-Debye relaxation behavior taking place due to the surface effects. The electrolytes were implemented in a zinc-air flow battery. Maximum power densities of 130 mW/cm2 (5% v/v DMSO) and 125 mW/cm2 (20% v/v DMSO) were obtained and were observed to be about 43% and 28% higher than that of the DMSO-free electrolyte. Results indicated that when 20% v/v DMSO was added to KOH solution, there was 67% zinc utilization efficiency (550 mAh/g) which provided 20% improvement in discharge capacity. Further, the battery with 20% v/v DMSO demonstrated excellent cyclability. Overall, DMSO shows great promise for enhancement of zinc dissolution/deposition in zinc-air batteries.

Three-Dimensional Fibrous Iron as Anode Current Collector for Rechargeable Zinc–Air Batteries

“…where α a and α c are the slopes of Tafel curves related to the anodic and cathodic branches of partial reactions, respectively. The corrosion rate (CR) generally corresponds to the corrosion current density along with the surface area of the working electrode (Zn) and alters due to porosity and accumulation of corrosion products [38]. CR can be determined by applying the parameters calculated, as in Equations (6) and (7), into the Faraday equation for linear polarization resistance, as shown accordingly in Equation (8):…”

“…Energies 2020, 13, x FOR PEER REVIEW 14 of 18 Typically, improving the solubility of ZnO in KOH can increase the average RTE and reduce the passivation of the Zn anode in an alkaline electrolyte [38]. As reported in a previous study, for a ZAB, RTE was enhanced through a newly designed catalytic dual-layer of a composite oxygen electrode, which could accelerate and catalyze the reaction of oxygen evolution at a lower potential range and achieved an RTE of 72.2% [43].…”

Enhanced Cycling Performance of Rechargeable Zinc–Air Flow Batteries Using Potassium Persulfate as Electrolyte Additive

“…the growth of dendrite during charging and the corrosion of the Zn anode due to the hydrogen evolution reaction (HER) [ 23 ]. In addition, one of the most challenging issues of using KOH in ZABs is the accumulation and precipitation of discharged products on the active Zn surface, leading to an undesirable passivation effect and the degradation of battery performance [ 16 ]. Therefore, the selection of a suitable electrolyte is crucial in improving cycling performance and battery efficiency.…”

Silver Decorated Reduced Graphene Oxide as Electrocatalyst for Zinc–Air Batteries

“…Zinc-air batteries (ZABs) have exhibited high potential for various energy applications because of their cost effectiveness and very high energy density (1.35 kWh/kg) [7][8][9][10]. Zinc (Zn) is an attractive electrode material because it is light-weight, non-toxic, inherently safe, inexpensive, and abundant [11,12].…”