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Lithium-Air-Accumulator

Development of a chemical-physical model of a lithium-air-accumulator using tomographic in-operando chracterisation methods and impedance spectroscopy

  • Joint project
  • Partner: Helmholtz Center Berlin for Materials and Energy
  • Sponsored by DFG
  • Project duration: 2017 - 2019

The three-dimensional structural and morphological processes taking place in a lithium-air battery have so far been insufficiently studied and understood. This represents a major obstacle in the development of innovative electrode structures. The aim of the proposed project is to provide a detailed picture of the inside of a Lithium-Air-Accumulator through a combination of innovative experimental in-operando methods (three-dimensional X-ray phase-contrast tomography and impedance-based analysis methods) during cycling to undergo structural and morphological processes and based on a chemical-physical 3D structure model of the electrodes to create, which is correlated with the real microstructural properties. With (synchrotron) X-ray tomography, the three-dimensional distribution of the different reaction products and deposits during loading and unloading is quantitatively recorded and described, depending on the structure of the electrodes, and combined with the impedance data. Thus, a better understanding of the basic processes of cycling is to be achieved. Simulation models based on the developed model then serve to develop and predict battery behavior under different operating parameters, and will ultimately be used to optimize electrode structures. In summary, the following priorities arise:

  • Assembly of lithium-air coin cells from self-synthesized materials
  • Tomography experiments to elucidate the reaction processes/ageing
  • Cell Characterisation by Impedance Spectroscopy
  • Creation of a simulation model

 

 

Fabrication of suitable electrode materials

The main focus of this topic is the synthesis of several high porous carbon materials with an active surface area of more than 100 m²/g for optimal adsorption of oxygen which is required for the battery reaction.

Furthermore the impact of several transition metal compounds (e.g. metal oxides, metal cluster, etc.), acting as catalysts for the cell chemistry (ORR/OER), is part of the investigation. This can lead to a better understanding of the cell processes and also help increasing the power density.

By using the scanning electron microscopy (SEM) the size of the synthesized graphite structures and the distribution of the catalytical centers can be detected and characterized. 

Manufacturing of battery electrodes

The main focus is directed at the fabrication of gas diffusion electrodes. Finding a well-suited binder composition and improving the reproducibility during the fabrication process of the electrodes are equally important for the cell assembly.

Manufacturing Lithium-Air-Accumulator cells

CR2032 button cells are assembled under protective gas atmosphere. Many factors during the manufacturing process have a direct influence on the cell performance (for example adjusting the correct crimping pressure for the battery materials, stamping size of the separator foil, etc.). Parallel to mechanical impacts on the battery performance the influence of different battery electrolytes is investigated.

Cell characterisation

The manufactured Lithium-Air-cells are cycled under different gas atmospheres. Varying analytical methods are used to characterize the influence of the battery modifications (for example different electrolyte compositions, electrode thickness, etc.) on capacity and power density.

Zusatzinformationen / Extras

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Contact

M.Sc. Dennis Meiling
030 314 73613
Room EMH 131

Address

Technische Universität Berlin
Electrical Energy Storage Technology
Institute of Energy and Automation Technology
Faculty IV
sec. EMH 2
Einsteinufer 11
D-10587 Berlin