A Chronocoulometric Method to Measure the Corrosion Rate on Zinc Metal Electrodes

Abstract

Research studies on zinc metal-based batteries have attracted considerable attention as a candidate for post-lithium-ion batteries. Zinc is one of the few metal anodes that is compatible with aqueous and non-aqueous electrolytes, providing a large theoretical capacity of 820 mAh g −1 . However, in aqueous electrolytes, the zinc metal anode suffers from hydrogen evolution reaction (HER), by which zinc is irreversibly consumed or corroded continually. Exact estimation of the corrosion rate has been a challenge in the development of Zn-based batteries. Measurement of the corrosion rate by conventional Tafel analysis meets serious problems because the cathodic current reflects deposition of Zn metal as well as HER, inhibiting exact measurement of the corrosion rate. Herein, we developed a chronocoulometric "deposition-rest-dissolution" method to quantify the corrosion rate without such interference from the deposition of Zn. The method was successfully applied to the quantification of the rate of chemical corrosion of Zn in aqueous electrolytes with various pH and concentration values. The "deposition-rest-dissolution" method and electrochemical impedance spectroscopy confirmed that saturated ZnSO 4 (ca. 3.2 M) + 0.075 M Li 2 SO 4 delivers the lowest corrosion rate compared to the other electrolytes, probably because the activity of water in such a concentrated electrolyte is low enough to suppress the kinetics of HER. Moreover, this method can be generally applied to determine the rate of chemical corrosion on various metal electrodes.

Simultaneously Regulating Uniform Zn2+ Flux and Electron Conduction by MOF/rGO Interlayers for High-Performance Zn Anodes

“…As depicted in Fig. 5 e, the anode exhibits both increased corrosion potential (from 0.016 to 0.032 V) and decreased corrosion current (from 2.63 to 0.71 mA cm −2 ) under the protection of MOF/rGO interlayers, elucidating a higher electrochemical stability against corrosion in electrolyte [ 50 ]. Finally, the stability of the MOF layer on Janus separator after battery cycling was validated by the strong characteristic XRD peaks of MOF (Fig.…”

High-surface-area titanium nitride nanosheets as zinc anode coating for dendrite-free rechargeable aqueous batteries

“…S10b shows the exchange current density (j) and the corrosion potential (E) (j Zn = 4.074 mA, j h-TiNs@Zn = 3.236 mA, E Zn = −0.984 V, E h-TiNs@Zn = −0.980 V). The corrosion potential of the electrode shifted toward positive potential and the current density decreased after spraying h-TiNs [39]. It was generally accepted that a more positive corrosion potential and a low corrosion current density indicated less tendency to corrode [11].…”

Potential-Dependent Passivation of Zinc Metal in a Sulfate-Based Aqueous Electrolyte

“…Since the pioneering work of Galvani and Volta revealed its electrochemical activity, zinc has been recognized as a scientifically and practically important electrode. It has been successfully used as a metallic anode for primary batteries owing to its large theoretical capacity (820 mAh g –1 ), high recyclability, low toxicity, low price, and low redox potential. − Furthermore, rechargeable zinc–air batteries (RZABs) are among the next-generation batteries because of their theoretical energy density of 1086 Wh kg –1 or 6136 Wh L –1 ; these values are approximately four times larger than those of lithium-ion batteries. , For the practical deployment of zinc metal in secondary batteries, it is necessary to overcome the following challenges: (1) dendrite formation; (2) structural deformation; (3) precipitation of unwanted salts (such as ZnO), which leads to higher internal resistance; and (4) hydrogen evolution reaction (HER), which lowers the coulombic efficiency. ,, …”