Implications of Testing a Zinc-Oxygen Battery with Zinc Foil Anode Revealed by Operando Gas Analysis

Recent development and applications of differential electrochemical mass spectrometry in emerging energy conversion and storage solutions

Electrochemical energy conversion and storage are playing an increasingly important role in shaping the sustainable future. Differential electrochemical mass spectrometry (DEMS) offers an operando and cost-effective tool to monitor the evolution of gaseous/volatile intermediates and products during these processes. It can deliver potential-, time-, mass- and space-resolved signals which facilitate the understanding of reaction kinetics. In this review, we show the latest developments and applications of DEMS in various energy-related electrochemical reactions from three distinct perspectives. (I) What is DEMS addresses the working principles and key components of DEMS, highlighting the new and distinct instrumental configurations for different applications. (II) How to use DEMS tackles practical matters including the electrochemical test protocols, quantification of both potential and mass signals, and error analysis. (III) Where to apply DEMS is the focus of this review, dealing with concrete examples and unique values of DEMS studies in both energy conversion applications (CO2 reduction, water electrolysis, carbon corrosion, N-related catalysis, electrosynthesis, fuel cells, photo-electrocatalysis and beyond) and energy storage applications (Li-ion batteries and beyond, metal-air batteries, supercapacitors and flow batteries). The recent development of DEMS-hyphenated techniques and the outlook of the DEMS technique are discussed at the end. As DEMS celebrates its 40th anniversary in 2024, we hope this review can offer electrochemistry researchers a comprehensive understanding of the latest developments of DEMS and will inspire them to tackle emerging scientific questions using DEMS.

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

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 CO₃ ^2- 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.

Electrochemical Lithiation/Delithiation of ZnO in 3D-Structured Electrodes: Elucidating the Mechanism and the Solid Electrolyte Interphase Formation

Conversion/alloy active materials, such as ZnO, are one of the most promising candidates to replace graphite anodes in lithium-ion batteries. Besides a high specific capacity (q_ZnO = 987 mAh g^-1), ZnO offers a high lithium-ion diffusion and fast reaction kinetics, leading to a high-rate capability, which is required for the intended fast charging of battery electric vehicles. However, lithium-ion storage in ZnO is accompanied by the formation of lithium-rich solid electrolyte interphase (SEI) layers, immense volume expansion, and a large voltage hysteresis. Nonetheless, ZnO is appealing as an anode material for lithium-ion batteries and is investigated intensively. Surprisingly, the conclusions reported on the reaction mechanism are contradictory and the formation and composition of the SEI are addressed in only a few works. In this work, we investigate lithiation, delithiation, and SEI formation with ZnO in ether-based electrolytes for the first time reported in the literature. The combination of operando and ex situ experiments (cyclic voltammetry, X-ray photoelectron spectroscopy, X-ray diffraction, coupled gas chromatography and mass spectrometry, differential electrochemical mass spectrometry, and scanning electron microscopy) clarifies the misunderstanding of the reaction mechanism. We evidence that the conversion and alloy reaction take place simultaneously inside the bulk of the electrode. Furthermore, we show that a two-layered SEI is formed on the surface. The SEI is decomposed reversibly upon cycling. In the end, we address the issue of the volume expansion and associated capacity fading by incorporating ZnO into a mesoporous carbon network. This approach reduces the capacity fading and yields cells with a specific capacity of above 500 mAh g^-1 after 150 cycles.

Influencing Factors of Performance Degradation of Zinc–Air Batteries Exposed to Air

Zinc–air batteries feature high energy density, but they usually suffer from their short storage life after they start working, restricting their commercial applications. In the past, scholars did not reach an agreement on the influencing factors of the performance degradation of zinc–air batteries when exposed to air. Here, a series of comparative experiments were conducted to confirm the changes of the battery during storage after being exposed to air. The morphology and composition of the components of the battery were characterized by scanning electron microscopy (SEM) and X-ray diffraction analyses. SEM images revealed that with the increase of storage days, the corrosion of the zinc anode gradually deepens, but the surface morphology of the air cathode does not change much. The electrolyte of the batteries stored for different periods was examined through inductively coupled plasma spectroscopy and titration. After 20 days of storage, the concentration of CO32− reached 2.694 mol L−1, which indicates that more than 80% of the OH− in the electrolyte was consumed. The results show that after being exposed to air, the carbonation of the electrolyte is the main cause of the battery capacity decay.

Reproducible and stable cycling performance data on secondary zinc oxygen batteries

Electrically rechargeable zinc oxygen batteries are promising energy storage devices. They appeal due to the abundance of zinc metal and their high energy density. Research on zinc oxygen batteries is currently focusing on the development of electrode materials. Since the progress is rapid and no state-of-the-art is agreed upon yet, it is difficult to benchmark their performance. This circumstance also complicates the use of the generated electrochemical data for model-based research – simulating the processes in the battery requires reliable performance data and material properties from experimental investigations. Herein we describe reproducible data on the cycling performance and durability of zinc oxygen batteries. We utilize anodes and gas diffusion electrodes (with the bifunctional catalysts Sr₂CoO₃Cl, Ru-Sn oxide, and Fe_0.1Ni_0.9Co₂O₄ with activated carbon) with low degradation during cycling, and present voltage data of current-dependent discharge and charge. All in all, we stimulate to reuse the data for parameter fitting in model-based work, and also to evaluate novel battery materials by preventing or minimizing side reactions with the testing protocol and setup utilized.

Measurement(s)	battery cycling performance • Voltage • Electrical Current • cycling stability
Technology Type(s)	galvanostat • electrochemical analysis

Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.13066070