As we mentioned in a previous post, at CIC energiGUNE, we are experts in aging and post-mortem analysis of different electrochemical energy storage systems; that´s why we like to call ourselves the CSI of batteries.

Why CSI (Crime Science Investigation)?

Because we are in charge of finding the failure mechanisms and elucidating the causes that have resulted in the malfunction and/or premature death of the battery.

Sometimes these failures are followed by unwanted side effects that compromise the user’s and his environment’s safety, such as harmful gas leaks or spontaneous ignition. This is why it is so important to relate the degradation processes to the current state of health of the batteries, in order to carry out preventive maintenance that alerts us in advance of possible failures and their consequences.

The state of health of a battery (SoH)

The state of health of a battery (SoH) at a given time is measured as the discharge capacity (Ah) at that time with regard to the initial discharge capacity; and is indicated by the corresponding percentage.

In this sense, the SoH depends significantly on the conditions of use of the battery during its lifespan, mainly temperature, depth of discharge and discharge flow.

Variations in these three parameters cause chemical reactions and/or mechanical degradation processes at cell level in materials and electrodes, which manifest themselves as a reduction in the discharge capacity and an increase in electrical resistance. These degradation mechanisms lead to battery failure, resulting from gradual and relatively long evolutionary processes, instantaneous catastrophic events, or a combination of both.

Detailed knowledge of the possible failure types allows the early design of the battery management strategy to extend its life and optimize its operation. At CIC energiGUNE, we achieve this important milestone by relating battery cycling conditions (usage) to post-mortem analysis.

To this end, electrochemical tests and characterizations are performed, which are integrated into advanced multimodal models based on the system’s physical electrochemistry. Thus, it is possible, for example, to estimate the SoH of batteries from the in-operating data of the battery impedance measurement.

Post-mortem analysis

In order to validate and optimize these models, post-mortem analyses are performed, starting with the disassembly and visual inspection of the battery and its components under standardized safety and material treatment procedures.

Then, physical-chemical and morphological studies are carried out to characterize in detail the composition and structure of electrodes and electrolytes, as well as the contact surfaces between them. In this way, impurities, intrinsic and extrinsic deterioration of materials, products and waste compounds that have originated through undesired reactions and/or degradation processes are detected.

Finally, in collaboration with our spin-off company BCARE, these failure modes identified through post-mortem analysis are implemented as feedback into predictive diagnostic models that will predict service life, avoid premature failure, reduce maintenance costs and extend system uptime in general.

Ante-mortem analysis

Complementing the above, ante-mortem analysis allows us to provide a complete evaluation of commercial cells using a combination of conventional analytical tools and other advanced non-destructive tools.

In this sense, we support, as neutral third-party experts, integrators, users and industrial partners to optimize their decision process based on comprehensive analysis of the quality of components and assembly of different types of batteries and supercapacitors.

Through these analyses, we can identify, for example, failures or errors in the manufacturing processes such as the existence of protective layers or adhesives that have not been removed before continuing with the assembly process, defective welding between cells, or current collectors that are not in contact with the electrodes.

The combination of the results extracted together from the ante-mortem and post-mortem analysis allows us to propose solutions to meet the technical and market requirements, helping to increase the cyclability, durability and safety of the cells.

During our trajectory, we have carried out ante- and post-mortem tests for several companies working in different industrialization sectors at both stationary and mobility applications. From Basque companies like IBERDROLA, CAF, BCARE, ZIGOR, or CEGASA, to large multinationals like AEG, SKELETON or VOLVO.

In all cases, we have provided value in their technological decision processes and operational integration of different storage systems in target applications by identifying critical processes and components that should be optimized before their commercial implementation.

As significant examples, lead-acid batteries´ most common failure patterns correspond to electrolyte stratification, positive collector corrosion, water loss, and component assembly errors.

Regarding lithium-ion batteries with iron phosphate cathode (LiFePO4), failures have been identified corresponding to the deposit of lithium on the electrodes, decomposition of salts of the electrolyte on the anode and structural changes in the active materials.

Solutions for the energy storage market

Overall, CIC energiGUNE offers customized solutions aimed at manufacturers, integrators and users of energy storage systems who want or need to analyze the failure mechanisms of a given battery, require advice on choosing the most appropriate components for their application depending on the technology, the chemistry and suppliers, or need to improve or optimize the manufacturing process of cells and batteries.

A unique and essential tool to continue moving forward with a firm step towards the much-desired energy transition that pivots on the electrochemical storage systems in general and on the batteries in particular, as a critical lever towards the decarbonization of transport and sustainable generation based on renewable energies.

All of this must culminate in a more ecological society, with productive processes free of contaminating emissions, and where the care of the environment is a key factor that does not limit the country´s growth model.

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