Study on failure mechanism on rechargeable alkaline zinc–Air battery during charge/discharge cycles at different depths of discharge

Abstract

Background: Zinc-air battery (ZAB) is a promising candidate for energy storage, but the short cycle life severely restricts the wider practical applications. Up to date, no consensus on the dominant factors affecting ZABs cycle life was reached to help understanding how to prolong the ZAB’s cycle life. Here, a series of replacement experiments based on the ZAB were conducted to confirm the pivotal factors that influence the cycle life at different depths of discharge (DOD).Method: The morphology and composition of the components of the battery were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and chemical titration analyses.Result: SEM images and XRD results revealed that the failure of the zinc anode gradually deepens with the increase of DOD, while the performance degradation of the tricobalt tetroxide/Carbon Black (Co3O4/CB) air cathode depends on the operating time. The concentration of CO32− depends on the charge/discharge cycle time. The replacement experiments results show that the dominant factors affecting the ZAB’s cycle life is the reduction of active sites on the surface of Co3O4/CB air cathode at a shallow DOD, while that is the carbonation of the electrolyte at a deep DOD. The reduction of active sites on the surface of Co3O4/CB air cathode is caused by the coverage of K2CO3 precipitated by carbonation of the electrolyte, suggesting that the carbonation of the alkaline electrolyte limits ZAB’s cycle life.Conclusion: Therefore, this work not only further discloses the failure mechanism of ZAB, but also provides some feasible guidance to design a ZAB with along cycle life.

Origin of the Oxygen Reduction Activity on Boron-Doped Fe–N–C Catalysts for Zinc–Air Battery Applications

“…The blue highlighted portions in Figure e indicate the places where the electrolyte and zinc foil were changed. The decrease in the efficiency of the ZAB is due to various reasons such as ZnO passivation by concentration polarization, aerial CO 2 reaction with KOH to form K 2 CO 3 , etc . The experiment for the benchmark catalyst Pt/C + Ir/C combination was performed, and galvanostatic charge–discharge efficiency was found to be lower than the Fe–N&B/C-800S + Ir/C catalysts, shown in Figure S18a,b.…”

“…The decrease in the efficiency of the ZAB is due to various reasons such as ZnO passivation by concentration polarization, aerial CO 2 reaction with KOH to form K 2 CO 3 , etc. 68 The experiment for the benchmark catalyst Pt/C + Ir/C combination was performed, and galvanostatic charge−discharge efficiency was found to be lower than the Fe−N&B/C-800S + Ir/C catalysts, shown in Figure S18a,b. The round trip efficiency was estimated as 90.2%, whereas the benchmark catalyst (Pt/C + Ir/C) shows only 72.6% (Figure S18c).…”

Improving Cycle Life of Zinc–Air Batteries with Calcium Ion Additive in Electrolyte or Separator

“…A typical ZAB mold was applied in this work with the distance between the air cathode and the Zn anode of 1 cm and the active area of the electrode of 4.5 cm 2 [ 38 , 39 , 40 , 41 , 42 , 43 ]. In addition, another set of electrolytic cells was installed to explore the effect of the separator on the cycle life of ZABs, as shown in Figure 2 , which consisted of an electrolytic cell and a separator fixing plate ( Figure 2 a).…”

Recent progress of in-situ/operando characterization approaches of zinc-air batteries

“…Bifunctional means that the catalysts can catalyze both the oxygen reduction reaction (ORR) during discharge and the oxygen evolution reaction (OER) during charging. The excellent catalysts need to have high catalytic activity, be stable to the electrolyte at charge and discharge voltages, and have high selectivity without catalyzing the formation of by-products [6] .…”

“…However, in order to commercialize rechargeable ZABs, there are still some problems that need to be solved, such as short cycle life and high overpotential. The former is caused by variations in the charging and discharging process of the electrode, and the latter arises from the slow cathodic reaction kinetics [6] . These issues can be addressed by studying the battery behavior to achieve insights into the reaction mechanism [7,8] .…”