ANALYSIS: E-MOBILITY


of structural components. Additionally, laser-based manufacturing processes also reduce costs, due to their high processing speed and wear- free operation. For the future, four major


Figure 4: (top) scanning electron microscopy image of a laser-structured graphite anode and (bottom) laser-cut edge of a ceramic solid electrolyte processed with a picosecond pulsed laser system


LIBs and the transfer to an industrial production facility are also necessary to increase the overall TRLs. Furthermore, laser materials


processing can be used to improve the electrochemical properties of LIBs. Increasing the proportionate share of active materials to passive materials, such as the casing, enhances the energy density of a LIB. Therefore, thick- and highly-compressed electrode coatings in the battery can be used. However, a decreased fast charging ability caused by diffusion limitations in the electrodes is a major drawback. Introducing microscopic holes in the electrode coatings, as presented in figure 4a, can address this disadvantage. It was shown that short-pulsed laser beams are a suitable tool for the creation of such structures with micrometre precision26


.


Besides the enhancements of the charging and discharging performance of batteries with structured electrodes27


, an


increase in their lifetime also could be shown in empirical studies28


. Furthermore, with


laser structured electrodes a facilitated wetting with electrolyte was achieved29, 30


.


The TRL evaluation showed that the impact of electrode


structuring on varying substrate materials and the thermophysical ablation phenomena are not fully understood. Additionally, for enabling industrial production, a strong increase in the process speed of laser structuring is required and industrial quality standards have to be met. Moreover, laser materials


processing advances new battery types such as the ASSBs. ASSBs with favourable performance characteristics, for example the high energy density, are considered to be a promising battery technology31


Market availability of ASSBs is expected in the next few years32


. However, no production


routines have been established so far. The electrodes and the


“Four major trends can be identified: new applications, sustainable production, cheaper beam sources and digitisation”


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solid electrolyte layers must be cut to shape, as shown exemplarily in figure 4b, to assemble an ASSB. The solid electrolytes can be polymeric, ceramic or glass-ceramic materials33


and the highly


reactive lithium metal is used as an anode material34


, which


requires the integration of the production equipment into an inert gas atmosphere. The evaluation of the TRL


.


showed that parameter studies must be performed and quality measures have to be quantified. With production demonstrators, in-depth investigations under near series production conditions can be conducted. After that, the integration into pilot and industrial-scale equipment considering the periphery and quality monitoring systems should be initiated.


Outlook Laser materials processing in the field of e-mobility can contribute to a significant improvement in many applications. As shown in this article, this includes the enabling of fast charging through the cell-internal contacting of current collector foils, the introduction of microscopic structures and the additive manufacturing


trends can be identified: new fields of application, sustainable production, cheaper beam sources and digitisation. As it was presented, laser materials processing is indispensable for e-mobility and it can be assumed that in the long term it will become an essential part of the production of hydrogen fuel cells since processes for cutting, surface modification and joining are also needed in this field – even more so for new materials.


In addition to stable and


reliable manufacturing techniques to avoid scrap, other processes, such as rework or disassembly, will also be required for a sustainable production. Laser processes allow for rework due to their high flexibility. With the high precision of the laser beam, components can be disassembled without harming the surroundings, and therefore it can enable a process for products that cannot be disassembled otherwise. As a result, laser- based applications promote the circular economy. For safety-critical products, such as battery storages or hydrogen fuel cells, a 100 per cent quality assurance is essential. To be economically competitive, this can only be done by inline process monitoring and suitable evaluation algorithms. Digitisation can also extend the availability of laser sources through predictive maintenance and increasing throughput via data-based optimisation. l


Christian Geiger and Tony Weiss are research associates at the Department of Laser Technologies at the Institute for Machine Tools and Industrial Management, part of Technical University of Munich’s Department of Mechanical Engineering


References


A list of references is available in the online version of the article at www.lasersystemseurope.com


AUTUMN 2021 LASER SYSTEMS EUROPE 27


Geiger et al.


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