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Über dieses Buch

This book contains a novel combination of experimental and model-based investigations, elucidating the complex processes inside zinc air batteries. The work presented helps to answer which battery composition and which air-composition should be adjusted to maintain stable and efficient charge/discharge cycling. In detail, electrochemical investigations and X-ray transmission tomography are applied on button cell zinc air batteries and in-house set-ups. Moreover, model-based investigations of the battery anode and the impact of relative humidity, active operation, carbon dioxide and oxygen on zinc air battery operation are presented. The techniques used in this work complement each other well and yield an unprecedented understanding of zinc air batteries. The methods applied are adaptable and can potentially be applied to gain further understanding of other metal air batteries.

Inhaltsverzeichnis

Frontmatter

1. Introduction

Abstract
The limited amount of available conventional energy resources and the increasing energy demand in the 21st century require sustainable and efficient energy conversion. As a consequence thereof, further well-engineered energy storage devices for mobile and portable consumer electronics, automotive applications, and large scale energy storage are needed in the nearby future. This holds especially if energy is utilized from intermittent sources, such as wind power or solar power. Within this scope, battery technology is one promising field of energy storage.
Daniel Schröder

2. Motivation and Scope of this Thesis

Abstract
The previous chapter has indicated that the electrically rechargeable zinc air battery has an enormous potential to be widely used for future energy storage. However, only limited charge and discharge cycle numbers can currently be achieved due to the unresolved issues mentioned. Almost all aforementioned issues of zinc air batteries that are addressed in research, are related to the materials applied or to the design chosen. Thus, they might be resolved with the help of material sciences and system design approaches.
Daniel Schröder

Characterizing Reaction and Transport Processes

Frontmatter

3. Basics of the Experimental Methods Applied

Abstract
As mentioned in subchapter 1.2, a systematic investigation of the reaction and transport processes can help to gain a better understanding of ZABs, aiming to improve them further. In the first part of this thesis, experimental methods are chosen as tool to qualitatively assess the impact of various battery and operation parameters on the processes inside ZABs.
Daniel Schröder

4. Experimental Set-Ups and Measurement Details

Abstract
In the previous chapter, the basics about the experimental methods applied in this thesis were given. In the following, the actual realization of these techniques for this thesis, with all parameters and experimental set-ups used, is introduced. The experimental analysis in this thesis is conducted to reveal detailed information e.g. on the cell potential and the solid and liquid species volumes in ZABs. However, not every experimental set-up is suitable for every measurement technique introduced.
Daniel Schröder

5. Experimental Results and Discussion

Abstract
In the following chapter the electrochemical measurement and X-ray analysis results are presented. These experimental results will reveal detailed information about the operation of ZABs, which will then be correlated to the electrochemical and chemical reactions, and the transport of reactants and electrolyte inside the battery.
Daniel Schröder

6. Detailed One-Dimensional Air Electrode Model

Abstract
As observed in the previous chapter, the volume expansion of the zinc electrode during ZAB discharge can flood the pores of the GDL with liquid electrolyte. A model-based analysis is applied in this chapter of the thesis to assess the implications of flooding on the air electrode overpotential, and the oxygen distribution within the air electrode. This chapter is based on the publications [72], [73], and [74].
Daniel Schröder

Identifying Factors for Long-Term Stable Operation

Frontmatter

7. Theoretical Considerations on Air-Composition Impact

Abstract
As mentioned in subchapter 1.1, the main advantage of ZABs, the superior theoretical energy density, originates from the fact that O2 is not stored within the cell but is taken from the surrounding air. This requires on the one hand an open air electrode concept for ZABs, but makes on the other hand the entire system susceptible to the surrounding air [1]. Passaniti et al. present a comprehensive overview, and state experimental results on the impact of the surrounding air on ZAB button cells [29]. However, the overview is not given for the operation of electrically rechargeable ZABs.
Daniel Schröder

8. Model Approach to Reveal Air-Composition Impact

Abstract
In this chapter, first a brief overview on existing model approaches to describe ZABs and further electrochemical systems is given. Subsequently, the set of equations for the versatile and expandable basic model for electrically rechargeable ZABs is introduced. The basic model is then modified to account for certain scenarios of air-composition and operation strategies: (a) reference scenario, (b) relative humidity scenario, (c) active operation scenario, (d) carbon dioxide scenario, and (e) oxygen scenario. All presented equations and the main thoughts on the model approach, as well as the underlying assumptions are based on the publication [85].
Daniel Schröder

9. Simulation Results and Discussions for Air-Composition Impact

Abstract
In the following chapter, the simulation results for the reference scenario and the scenarios for the air-composition impacts are presented. The respective subchapters aim to assess the challenges that arise from the fact that ZABs are half-open to the surrounding air. The model approach and the simulations conducted in this chapter are based on a previously published journal article [85], and are extended by several simulations.
Daniel Schröder

Backmatter

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