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Electrical Energy Storage TechnologyCell Assembly

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Cell Assembly

A continuous improvement of existing battery concepts (e.g. lithium-ion-batteries) and a development of novel technologies (e.g. lithium-air or zinc-air) involves the requirement of a testing setup in order to assess single battery components (e.g. electrodes, separators, electrolyte, etc.) or complete cells. Special testing and measuring cells, also called analytical cells, or coin cells are used to enable testing setups considering real operation conditions including different test scenarios (e.g. cyclisation, electrochemical impedance spectroscopy (EIS), cyclic voltammetry, etc.).

The assembly of coin and analytical cells has to be performed in a special atmosphere (e.g. glovebox) for protective reasons of single components against air, water and nitrogen. In addition, appropriate specialized tools (e.g. coin cell press) are needed. Subsequent cyclisation and analysis are performed using special hardware (e.g. Neware, Ivium, Zahner).

The obtained results enable predictions for scaling the components to larger battery formats and a better understanding of occurring electrochemical processes. Furthermore, different battery models can be parameterized (e.g. in COMSOL) optimizing the utilization of batteries and battery systems.

 

 

Coin Cells

Lupe

Coin cells are compact batteries that are often used where space is limited or power consumption is low. According to IEC 62281, coin cells are defined as "small round cells whose overall height is smaller than their diameter". Typical fields of application are car keys, wristwatches and calculators. Due to the simple structure, the small amount of material used and the possibility of manual production, coin cells allow a cost-effective investigation of innovative or optimized battery materials in the field of research and development. Designations for coin cells (for example CR2032) generally contain informations on the cell chemistry used (C: lithium manganese dioxide), the diameter (20: ⌀20mm) and the total height (32: 3.2mm). Coin cells of type 2032, which are the most common coin cell format for experimental investigations, are composed of electrodes, the electrolyte, a separator and a spring and at least one spacer. Depending on the materials used and the quality characteristics examined, the series order of the cell components may vary

Test Cells

Lupe

Test cells are available in both coin cell and pouch cell formats. One possibility to examine cell materials in the coin cell format is the ECC-Ref test cell from EL-CELL. In contrast to the coin cell, the housing is not pressed but screwed together. This allows multiple use. In addition, special spacers within the cell and a separator carrier, which forces an alignment of the electrodes ensure a higher reproducibility compared to coin cells. These separator carriers may also be provided with reference electrodes to enable three-electrode measurements. In Lithium-Ionen-Batteries lithium reference electrodes can be used to detect the potential drop to 0V vs. lithium to determine the critical point of metallic lithium deposition causing lithium plating. The three electrode measurements can also be used to perform separate EIS-measurements for anode and cathode.

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