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The development of next-generation lithium-ion batteries with volumetric energy densities > 750 Wh/L and gravimetric energy densities > 400 Wh/kg is a key objective of the European Union’s Strategic Energy Technology Plan to be achieved by 2030. Both new materials and production strategies play an important role in the development of those batteries. Thick-film electrodes are advantageous to increase the volumetric and gravimetric energy densities alike since the amount of inactive material can be reduced. To facilitate higher C-rates during (dis-)charging in thick-film electrodes, laser generated structured are introduced, thus creating new lithium-ion diffusion pathways leading to a reduced cell polarization. Additionally, electrode wetting with liquid electrolyte is significantly improved, reducing the risk of dry spots in the electrode stack. Industry interest in implementing laser patterning of electrodes into existing or planned manufacturing lines has increased significantly in recent times. The strip speeds of electrode production are decisive for the required speeds to be realized in laser structuring. Various technical approaches can be applied to upscale the laser patterning process such as multibeam processing which can be realized by splitting a laser beam into several beamlets with a DOE. In this work, a large field scanner and a related optical lens system are combined with an ultrashort pulsed, high repetition rate, high power laser source. The ablation behavior of commercial graphite composite electrode material was investigated for upscaling using different laser patterning scenarios.

Structuring of electrodes for lithium-ion batteries by using ultrashort pulsed laser ablation is a quite promising approach to significantly increase the electrochemical performance of lithium-ion batteries. The main impact of such 3D electrodes is due to shortening of lithium-ion diffusion pathways and improving the electrolyte wetting of composite electrodes The latter is reducing the electrolyte filling process time and saving the need for warm aging in the manufacturing process. The 3D electrode concept, in combination with an increase in electrode layer thickness, facilitates an increase in energy and power density of batteries at the same time. To implement the laser structuring process in industrial cell manufacturing, an adaptation of the ultrafast laser technology to the coating speed has to be established. In the presented study, the use of an ultrashort pulsed laser system of high power up to 300 W and high repetition rate in the MHz regime was evaluated regarding processing speed for patterning of graphite and silicon/graphite anodes. For composite graphite anodes (film thickness > 76 µm) with an areal capacity of about 2.5 – 4.0 mAh/cm2 and a thick-film silicon/graphite anode with 5 wt.% silicon content (film thickness 80 µm, areal capacity 4.3 mAh/cm2) the laser and process parameters and processing speed were evaluated and optimized. Furthermore, different structure patterns including hole, grid and line pattern, were studied regarding upscaling in roll-to-roll processing. The different types of patterns were evaluated with respect to accessible electrochemical properties. Prior to cell assembly and during post-mortem studies, the quality of structured electrodes was examined by profilometry and scanning electron microscopy. Debris formation and a thermal impact to active material and current collector could be avoided. To evaluate the electrochemical properties such as high rate capability, cell impedance, and cell lifetime, coin cells and pouch cells were manufactured. For this purpose, NMC 622 cathodes were prepared as the respective counter-electrodes and a cell balancing in the range of 1.1-1.2 was ensured.

During the next decades, combustion driven cars will be completely replaced by electrical vehicles (EVs) and it seems quite obvious that liquid electrolyte lithium-ion batteries (LIBs) will be the dominating energy storage system for the next at least 5 to 10 years. As a consequence, in Europe numerous Gigafactories have recently been planned with this state of technology. However, the current lithium-ion battery technology suffers so far from some restrictions like the inability to combine high power and high energy operations at the same time. This limitation is mainly attributed to the cathode architecture and respective mass loading. In addition, the further demand for a significantly enhanced fast charging mainly requires an optimization of the anode design flanked by a high areal capacity. Advanced 3D electrode architectures based on a thick film electrode concept seem to be the most promising approach to overcome the current limitations in battery performances. However, respective technology innovations need to provide a high compatibility grade to existing manufacturing routes in order to enable the required integration in existing and planned factories. For so-called “generation 3” materials, i.e., nickel-rich lithium nickel manganese cobalt oxide (NMC) cathode and silicon-based anode materials, structuring technologies using cutting edge ultrafast high power lasers, are being developed in order to manufacture 3D electrode architectures with high areal capacity. Multibeam laser processing using diffractive optical elements and dual scanner approaches were established in order to enable high processing speeds in roll-to-roll electrode handling systems. The technology readiness level (TRL 6) is demonstrated for pouch cells geometries. For water-based NMC 622 and silicon-graphite composites the laser structuring process was developed. Different structures including hole, grid, and line patterns, were studied regarding their impact on electrochemical performances such as high-rate capability and cell lifetime. Lithium concentration profiles of unstructured and structured electrodes were studied post mortem using laser-induced breakdown spectroscopy (LIBS) in order to evaluate lithium intercalation/deintercalation efficiencies and detect possible cell degradation processes. In comparison to unstructured electrodes, 3D electrodes could hereby always be identified as superior: unstructured thick film electrodes show a significant drop in capacity retention for high power operation and tend to form hot spots acting as starting point for cell failure. The upscaling process is flanked by a further improvement of electrode design. For this purpose very recently laser induced forward transfer (LIFT) is applied as printing technology to draw new concepts for sophisticated model electrode architectures with advanced electrochemical performances. Finally, the micro-/nano-scaled texturing of current collectors and separator material is discussed as further possible approaches for boosting the electrochemical performances of LIB pouch cells.

In additive manufacturing processes, components are built up in layers from liquids, powders, wires or foils using chemical or physical processes. Direct energy deposition (DED) or powder bed fusion (PBF) can be used as additive manufacturing processes in which metal powder or wires are used to print dense metal layers on substrates or on freeform surfaces of existing components [1]. Metal powder (pure elements, element mixtures, master alloys) or metal wires are melted at high speed and instantaneously deposited in layers on respective metallic substrates. In case of the so-called laser cladding [2], this technology is generally used for applying coatings or for tool repairs. Compared to subtractive processes, additive processes save time and resources, as the material is only added where it is needed. Established steels, nickel-based alloys or titanium alloys are typically used. However, it is also possible to obtain completely new materials by in-situ alloying of powder mixtures or to create material gradients by changing the powder mixture composition during the build-up [3]. High entropy alloys (HEAs) represent a new research field for future applications. These are formed from a large number of elements, all of which are present in similarly strong concentrations e.g., alloys consisting of zirconium, niobium, hafnium, tantalum or tungsten [4]. The alloys formed can generally be single-phase as well as multi-phase mixed crystals. HEAs can often combine high strength and very good ductility. In-situ alloying offers the unique possibility of fast material screening for the future production of new metallic components with outstanding mechanical properties at high temperatures. For a long time, the manufacture of refractory alloys was limited to vacuum arc remelting because of their high melting points. With laser-based methods, these metals are locally melted by the focused laser beam and deposited additively. In addition to material development, additive manufacturing offers great design freedom in component design, which can be used, for example, for the development of load-optimized designs based on the bionic principle [5]. To add up to the versatility of additive manufacturing, laser post-processes can be used to modify the resulting surfaces of parts produced with such technology [6-9]. The different types of laser sources commercially available assure their suitability in a wide range of applications, with continuous wave (cw) lasers being often used for reduction of surface roughness, while pulsed lasers being applied in the modification of surface functionalities and to enhance the geometry accuracy. Even with the prospect of being able to replace certain steps of the additive manufacturing process chain, adopting laser post-processes as an additional step can also be proved beneficial when specific characteristics are required in localized areas of the final built components.

Rapid manufacturing of functionalized polymers enable a cost-efficient method for many applications in the biological, and medical sector. Laser structuring techniques differ for fast fabrication processes of thermoplastics. Here we report on direct UV laser ablation of polystyrene and polydimethylsiloxane to control wettability and bio-compatibility. For this purpose contact angle measurements and L929 cell growth experiments were performed as function of laser and process parameters. This work also describes the potential of laser-assisted hot embossing which has been introduced to replicate pre-fabricated micro- and nano-sized structures onto polymers proving it to be a cost-efficient and flexible method for surface functionalization. Therefore, pre-fabricated laser-induced periodic surface structures have been manufactured as mould inserts using ultrafast laser radiation near the ablation threshold. These mould inserts can also be made of nickel, silicon or glass proving laser-assisted hot embossing to be a versatile tool for the functionalization of thermoplastics and meet the requirements for modern manufacturing with regard to quality and production flexibility.

Graphite composite electrodes mixed with silicon are proposed as next generation anode material for high energy and high power applications. In order to overcome drawbacks caused by volume changes of silicon particles during electrochemical cycling and to maintain high specific capacities at enhanced C-rates, free-standing structures are generated on silicon/graphite electrodes by applying ultrafast laser ablation. Electrochemical properties are systematically investigated by means of galvanostatic measurements, cyclic voltammetry, and electrochemical impedance spectroscopy. Cells with structured electrodes exhibit improved battery performances and lithium-ion transport kinetics in comparison to cells with unstructured electrodes. Furthermore, the cells with structured electrodes exhibit a lower impedance at fully lithiated state. After cycling, post-mortem analysis is performed revealing that the mechanical stress within the electrodes and current collector can be significantly reduced due to laser generated free-standing structures.

In this study, the effect of laser induced periodic patterning of α-β titanium alloy (Ti-6Al-4V) developed by excimer laser (ArF, with a laser fluence of 2.4 J/cm2, a laser pulse repetition rate of 200 Hz and 50 laser pulses) and Fiber laser (using a power of 5 W, frequency of 80 kHz, scan speed of 800 mm/s and 2 times scanning) on its microstructure and corrosion behaviour have been investigated. The microstructure of the patterned surface shows a significant refinement of grains with the presence of α and β. A very low mass fraction of TiO2 was noticed when patterning was performed using ArF laser. A significant improvement in total surface energy (from 37 mN/m for Ti-6Al-4V to 41 mN/m for ArF laser patterned surface and 40 mN/m for Fiber laser patterned surface) and polar energy (from 11 mN/m for Ti-6Al-4V to 26 mN/m for ArF laser patterned surface and 24 mN/m for Fiber laser patterned surface) have been observed. Corrosion rate was reduced due to laser patterning (from 6.12 mm/year for as-received Ti-6Al-4V to 2.17 × 10−2 mm/year for ArF laser patterned and 1.68 × 10−2 mm/year for Fiber laser patterned Ti-6Al-4V surfaces). Laser surface patterning improved apatite deposition from 15% area coverage for Ti-6Al-4V to 34% and 33% area coverage for ArF and Fiber laser patterned surfaces, respectively.

Quantitative chemical mapping of battery electrodes is a rather new post-mortem analytics method for identifying and describing chemical degradation processes in lithium-based battery systems. In consideration of future applications, the development of lithium-ion batteries is quite essential in order to meet requirements such as improved cell lifetime (>5000 cycles), high energy density at the cell level (>250 W h kg), reduced charging times (2500 W kg), and reduced manufacturing costs (

Tuning of electrochemical properties of lithium-ion batteries by using ultrafast laser structuring of electrodes is a rather new technical approach. At Karlsruhe Institute of Technology (KIT) this technology was developed and established for the first time. However, quite recently, other research groups and institutions worldwide also recognized the high potential of this technology for lithium-ion battery production. Lately, a roll-to-roll laser processing infrastructure for structuring large footprint electrode materials for high capacity pouch cells and cylindrical cells was installed at KIT in order to push this technology to demonstrator level, namely technology readiness level 6. The high rate capability of the produced high energy battery cells were significantly improved and twice lifetime of cells could be achieved in comparison to cells with unstructured electrodes. In frame of research, cooperative, and industrial projects the impact of laser structuring for small and large footprint electrodes was studied with regard to lithium distribution caused electrochemical cycling. Hereby, different types of LiNixMnyCo1-x-yO2 (NMC) as a cathode material and graphite as well as silicon-graphite as an anode material with areal capacities up to 4 mAh/cm2 were investigated. Quantitative lithium distribution along entire electrodes were measured by laser-induced breakdown spectroscopy (LIBS). From the 3D elemental mapping starting points for electrochemical degradation could be identified. In cathode materials the local increase of lithium indicated the formation of electrical short cuts which were most related to electrode material inhomogeneity, e.g., by a macroscopic change in porosity or macroscopic film defects. The compressive stress applied to electrodes and separator during cycling has also a significant influence on lithium distribution and subsequent cell degradation. The appropriate type of laser generated patterns such as holes, lines or grids strongly depends on the application scenario as well as type of materials. For silicon-graphite anodes the huge volume expansion during lithium silicide needs to be considered and more rectangular and broader structure features become relevant. Laser structuring of electrodes showed in all cases, for small and large footprint cathodes and anodes, a rather homogenized lithium distribution along the surface and electrode thickness. For full cells elemental mapping of electrodes facing each other was performed indicating the mutual influence on lithium distribution. It can be concluded that the laser-based 3D electrode concept is beneficial regarding a reduced cell degradation. In addition, it could be proven by LIBS that for the 3D battery concept new lithium diffusion pathways were generated which becomes activated at elevated C-rates. Those new lithium diffusion pathways counteract the increase of diffusion overpotential leading to a higher capacities also for high power operation.

The development of high areal energy density electrodes with layered metal oxide cathode materials is currently worldwide a main topic in research and industry. Water-based binders were applied in the presented work for the manufacturing of NMC 622 (Li(Ni0.6Mn0.2Co0.2)O2) cathodes in order to achieve environmental friendly and cost-reduced production, replacing the conventional organic PVDF binder and the toxic and volatile NMP solvent. However, the pH value of aqueous processed cathode slurries increases to over 12 due to the reaction between NMC 622 particles and water, which decreases the specific discharge capacity of the cells and on the other side results in the chemical corrosion of the current collector during casting. In order to avoid the damage of the current collector and protect the cathode material, different acids could be applied during mixing process to adjust the slurry pH value. In addition, the energy density at battery level can be increased with increasing electrode film thickness which corresponds to an enhanced areal capacity. However, capacity fading of thick-film electrodes at C-rates above C/2 is mainly due to a limited lithium-ion diffusion kinetics and crack formation in cathode particles. 3D electrode architectures produced by ultrafast laser ablation are proven to improve the capacity retention at high discharge rates and the electrolyte wettability of electrodes as reported in our previous works. In this work, NMC 622 electrodes with a film thickness of 150 µm (5.8 mAh/cm2) were manufactured with aqueous binders TRD 202A and CMC, and were subsequently laser structured. With increasing film thickness from 70 µm to 150 µm, the mass loading of cathodes increased from 17 mg/cm2 to 36 mg/cm2. The slurry pH values were adjusted between 9 - 10 with citric acid (CA), phosphoric acid (PA), and acetic acid (AC). The dried electrodes were characterized using XPS and SEM. The unstructured and structured electrodes with different thicknesses were afterwards assembled versus lithium in coin cells. Rate capability test and cyclic voltammetry (CV) were performed in order to investigate the electrochemical performance of the electrodes. Cells containing 70 µm cathodes with PA and CA+PA showed about 10 mAh/g higher capacity at C/20 to C/5 compared to cells with PA, while at 1C to 3C cells with CA showed the lowest capacities With increasing electrode film thickness, cells with PA and PA+CA retained 5-10 mAh/g more capacity than cells with CA at C/20 to C/5. The cells with PA maintained about 120 mAh/g discharge capacity at C/2, while cells with PA+CA and CA showed about 80 mAh/g and 45 mAh/g, respectively. In comparison to cells with unstructured electrodes, laser structuring increased the discharge capacity of cells with 70 µm electrodes from 1C to 3C, regardless of the type of added acid. As for cells with thick-film electrodes, the discharge capacity of cells containing structured electrodes with CA+PA increased to 120 mAh/g, which is about 40 mAh/g higher compared to cells with unstructured electrodes. Finally, CV proved that the addition of acids had no effect on the redox reaction of NMC 622.

Due to the advancing electrification in mobility, the production capacity of cells with high power and energy density needs to be increased, while a reduction in production costs is to be aspired. For the gravimetric energy density, 350 to 400 Wh/kg are defined as a goal from the European Union for the so-called cell generation 3b, which is to be achieved by approximately 2025. For this type of next generation lithium-ion batteries volumetric energy densities of about 750 Wh/L are targeted. For this purpose, novel anode materials with increased specific capacities have to be applied. Silicon is a promising candidate for this application, since it has a theoretical specific capacity of 3579 mAh/g at room temperature, which is one order of magnitude higher compared to the state-of-the-art graphite anode material (372 mAh/g). While silicon is lithiated, a volume change of about 280 % can be observed, which reduces the mechanical integrity of the electrodes and leads to a strong decrease in capacity and therefore a short cell lifetime. To overcome this issue, several approaches are pursued, whereof the most promising candidate to fulfil the requirements of scalability for industrial applications is the utilization of silicon nanoparticles. The establishment of a water-based slurry preparation process for silicon/graphite composite anodes with a fine dispersion of the silicon nanoparticles is crucial. Several manufacturing routes are investigated with special focus on the scalability, processability, spatial distribution of the binder, silicon and graphite active material as well as on the performance during galvanostatic cycling. Fur this purpose, different binder configurations are applied, where the amount as well as the degree of polymerization and substitution of sodium carboxymethylcellulose (Na-CMC) and the content of styrene butadiene rubber (SBR) are of interest. Additionally, the destruction of the silicon nanoparticle agglomerates, which can only be achieved with high intensity impact realized by a ball mill, is separated from the whole mixing process. Therefore, the destruction of the graphite active material by the ball milling process is reduced. A dry mixing process of the graphite and the conductive carbon black is investigated as well. The implementation of additional porosity with a laser patterning process was also proven to be effective to increase the cell lifetime of silicon/graphite composite electrodes. Therefore, an ultra-short pulsed laser source is applied to generate line patterns in the composite material. This significantly improves the wetting of the electrode with liquid electrolyte, but also reduces the mechanical stress inside the electrode due to the increased artificial porosity available for volume expansion which finally leads to an immense impact on cell lifetime.

In order to meet the target for the next generation lithium-ion batteries, electrochemical performance such as energy and power density must be increased significantly at the same time. Optimized electrode architectures including 3D battery concepts and advanced materials are in development to achieve this goal. The use of silicon-graphite composite electrodes instead of graphite anodes is currently investigated. This is due to the fact that silicon can provide almost one order of magnitude higher specific energy density (3579 mAh/g) in comparison to natural graphite (330 - 372 mAh/g). However, during lithiation, i.e., lithium silicide formation, a volume expansion of about 300 % can take place, while during lithium intercalation in graphite about 10 % volume expansion can be observed. A huge volume expansion leads to a tremendous mechanical degradation of the anode resulting in a drop in capacity, and a limited battery lifetime. In the presented study, laser induced forward transfer (LIFT) is applied as printing technology to develop sophisticated graphite and graphite-silicon electrode architectures with advanced electrochemical performances. LIFT was performed using a pulsed nanosecond UV laser with a repetition rate of up to 30 kHz and a maximal power of 10 W. To enable an accurate printing process during LIFT, the properties and compositions of the active material inks as well as the laser and process parameters have to be optimized. The printing process in combination with laser structuring provides a high flexibility regarding the final electrode design. In the presented study, the formation of multi-layer electrodes with spatial variation in electrode composition is achieved. As active materials silicon nanoparticles (SNPs) and various types of graphite, i.e., natural graphite, mesocarbon microbeads (MCMB), and artificial flake-like graphite with an average particle diameter of 1 µm up to 15 µm are utilized. The geometry and thickness of each printed layer is adapted with regard to an optimized electrochemical performance and cell lifetime. A single layer thickness of 5 µm up to 20 µm was achieved, while areal capacities of multi-layer anodes reaches values of 2 to 4 mAh/cm². In addition to the applied active materials and architecture concepts, different solvent and binder systems are investigated with regard to process scalability and an improved environmental compatibility. The printed electrodes are electrochemically characterized by rate capability measurements at C-rates of up to 5C. A correlation between capacity retention and electrode architecture is achieved. The results are discussed in terms of upscaling and impact on the next generation anode material.

The introduction of laser-generated 3D capillary structures in electrodes of Li-ion cells enables a more homogenized electrolyte wetting, which helps avoiding warm aging and shortens cell storage time prior and after electrochemical formation. In this study, the roll-to-roll (R2R) laser patterning of graphite anode material with a high-power ultrafast laser source was investigated. The governing parameters of laser structuring and their impact on active mass loss, electrode architecture, and electrolyte wetting behavior were analyzed. The trade-off between the quality of the structures and the processing times for an optimized R2R-processing was assessed. The application of a diffractive beam-splitter was evaluated.

Some Coleoptera (popularly referred to as beetles) can fly at a low Reynolds number with their deployable hind wings, which directly enables a low body weight-a good bioinspiration strategy for miniaturization of micro-air vehicles (MAVs). The hind wing is a significant part of the body and has a folding/unfolding mechanism whose unique function benefits from different structures and materials. This review summarizes the actions, factors, and mechanisms of beetle flight and bioinspired MAVs with deployable wings. The elytron controlled by muscles is the protected part for the folded hind wing and influences flight performance. The resilin, the storage material for elasticity, is located in the folding parts. The hind wings' folding/unfolding mechanism and flight performance can be influenced by vein structures of hollow, solid and wrinkled veins, the hemolymph that flows in hollow veins and its hydraulic mechanism, and various mechanical properties of veins. The action of beetle flight includes flapping flight, hovering, gliding, and landing. The hind wing is passively deformed through force and hemolymph, and the attack angle of the hind wing and the nanomechanics of the veins, muscles and mass body determine the flight performance. Based these factors, bioinspired MAVs with a new deployable wing structure and new materials will be designed to be much more effective and miniaturized. The new fuels and energy supply are significant aspects of MAVs.

Spatial profiling of the reactant and product concentration including the gas phase temperature during the selective oxidation of propylene to acrolein along a catalyst bed allowed locating and distinguishing between specific processes occurring in each individual point of a chemical reactor. For this purpose, a lab-scale testing setup capable of resolving concentration and temperature gradients in a fixed-bed reactor was developed. The local gas phase composition and temperature were determined using a sampling capillary and mass spectrometry along a multicomponent Bi–Mo–Co–Fe oxide catalyst bed during selective oxidation of propylene to acrolein under high conversion conditions. In this way, the reaction progress in terms of conversion, selectivities and yields along the reactor was revealed. While ca. 66% of the integral propylene conversion occurred in the first third of the catalyst bed with high selectivity towards acrolein, the latter third of the bed was dominated by the formation of acrylic acid and CO$_{2}$ as further and total oxidation products, respectively. Acrylic acid, which originates from the sequential oxidation of propylene to acrolein, was the by-product with the highest yield and especially formed above 440 °C. CO and CO$_{2}$ were observed directly from propylene, along with consecutive pathways of propylene oxidation, which favor CO$_{2}$ formation. The numerous insights obtained by even a single profile highlight the strong capabilities of spatially resolved activity and temperature measurements for diagnostics of packed-bed reactors and identifying the reaction pathways occurring within.

A simulation study performed in the scope of the project RealLi! is presented. One of the project’s main goals is to improve NMC811 and graphite electrode cycling capacities at high C-rates. The rapid charging and discharging capability of batteries is improved using laser ablation to introduce structures into the surface of the electrode composite layers. Due to improved transport kinetics, this not only improves the electrochemical properties in the high-current range, but also homogenizes and accelerates the electrolyte wetting during production as a side effect. This is particularly advantageous in thick-film electrodes for providing high energy densities. This study supports the laser structuring process of battery electrodes [1][2] via a virtual optimisation, based on electro-chemical battery models. The electrodes are structured by ultrafast laser ablation, with parallel channels being introduced along the electrode surface. This modification enables an easier electrolyte penetration, a reduced charge transfer resistance, and shortened lithium-ion transport pathways which finally leads to a reduced diffusion overpotential at high C-rates. The geometrical parameters of this process (pitch distance, width, and cross-sectional shape of laser-generated micro-channels) and their impact on cell performance are virtually optimised by simulations. The simulations are based on a homogenised multi-scale model, applied in 2D/3D macroscopic cuts, coupled with 1D microscopic particle cuts. The 2D/3D macroscopic electrolyte transport equations are common concentrated electrolyte equations. The microscopic particle transport equations are either a set of non-linear Fick’s Diffusion equations [3] that are used to describe spherical symmetric NMC811 materials or a set of Cahn-Hilliard equations [4] that consistently describe the phase separating nature of graphite anodes in cylindrically symmetric particles. The underlying numerical method is an implicit-multi-scale finite-element-method [3] that allows for a flexible implementation of such models. The first results of this ongoing project will be presented along with the overall structure of the method and its implementation. The results include geometrical as well as electro-chemical parameter variations and their respective sensitivity analysis. Furthermore, in the discussed electrode geometry the possible anisotropic structure of an electrode (due to particle shape and distribution) has a bigger impact than in unstructured electrodes. The improved transport pathways along the channels, therefore, imply the necessity of a more thorough homogenisation than it is usually done, for example in a Newman-Model approach. A long-term goal of this work is to enable a significant increase in areal energy density, i.e., the use of thicker electrode films and the use of advanced high energy materials in battery electrodes. [1]3D silicon/graphite composite electrodes for high-energy lithium-ion batteries, W. Pfleging et.al., Electrochimica Acta, Volume 317, 2019, Pages 502-508, J Power Sources 145 (5), 2345-2356 [2]Recent progress in laser texturing of battery materials: a review of tuning electrochemical performances, related material development, and prospects for large-scale manufacturing,W. Pfleging,International Journal of Extreme Manufacturing, Vol 3, 2020 [3]Derivation of a multi-scale battery model and its high-performance computing implementation, F. Pichler, Doctoral Thesis, Graz, 2018 [4]Phase Transformation Dynamics in Porous Battery Electrodes, R. Ferguson, M. Z. Bazant, Electrochimica Acta, Volume 146, Pages 89-97, 2014 Figure 1

Although there have been numerous attempts to define how different laser polishing parameters affect the generated surface roughness, there has been no detailed investigation of how their effects can be combined to optimize the process. This paper applies statistical analysis to model and predict the resulting surface roughness for laser post-processing of components made of Ti-6Al-4V and produced by laser powder bed fusion. This model is based on analysis of a wide ranging experimental programme investigating how the interaction of the governing parameters, i.e., laser power, number of repetitions, axial feed rate, scanning speed, and focal position, affected surface roughness. The experimental programme was the result of a robust Design of Experiments analysis and experimental analysis using ANOVA. It is expected that the outcomes will contribute towards the understanding of how the governing parameters influence the laser polishing process and final surface roughness, and would be a tool for optimizing their selection. The results of the ANOVA (analysis of variance) revealed that the most significant parameters are scanning speed followed by laser power and then axial feed rate. In addition, a clear tendency for the estimated Ra to decrease with the increase in laser power at lower values of axial feed rate and of scanning speed, and a focal position in the region of 2 mm. It is noted that the process parameters were varied over wide ranges, including extreme values, which made it difficult to accurately model the dependent variable over the full range of experimental trials.

This work investigated the effect of steel substrate topography and roughness on cathodic disbonding resistance and wet adhesion of the polyvinyl butyral/oxide/steel interface. Laser structuring was employed to pattern steel surfaces with controlled, periodic peaks of different peak-to-valley height, Rz, and geometry. Grinded smooth samples were used for reference. The in-situ scanning Kelvin probe technique was used to follow the cathodic disbonding in humid air and wet adhesion loss in inert atmosphere (3 ppm O2). Both cathodic disbonding and wet adhesion loss depended on the ability of the surface for mechanical adhesion, even when compensating for the increased effective contact area. X-ray photoelectron spectroscopy excluded the possibility for oxide chemistry effects on the delamination rate. Surfaces with features that enabled mechanical interlocking forces, had the best cathodic disbonding resistance and wet adhesion properties. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/).

Due to the increasingly severe soil compaction and plough pan thickening prevalent in agricultural practice, an increase in operating energy consumption and a decrease in crop growth has been observed. This paper aims to solve the problem of heavy tillage resistance by using riblet structures extracted from shark scales in the design a biomimetic shark-inspired (BioS) subsoiler. To produce better quality work, the design parameters of the BioS subsoiler, including the ratio of the riblet height to the riblet spacing h/s, the riblet height h, and the internal friction angle α, were considered, and a mechanical analysis of the relationship between the BioS subsoiler and the soil was performed to evaluate tillage resistance, total energy consumption and soil disturbance. The minimum tillage resistance and energy consumption of the shank and tine were achieved with an h of 5 mm and h/s of 0.57 obtained from the simulation results. Then, the parametrically optimized BioS subsoilers were fabricated and used to perform field experiments at different tillage speeds. The effects of subsoiling with BioS subsoilers and with an ordinary subsoiler (O–S) on the soil moisture, root morphology and crop yield were also discussed. The results showed that the BioS subsoiler would be helpful to increase the root absorption capacity of water and nutrients, which promote crop growth and increase the crop yield.

Laser polishing of metals consists of irradiating the part’s surface with a laser beam, thus generating a molten layer that is redistributed and resolidified to create a surface with reduced roughness. However, the process is also characterized by an instantaneously formation of heat-affected zones with consequent microstructural changes that influences the mechanical properties. In order to understand the microstructural evolution during laser polishing of Ti-6Al-4V laser-based powder bed fusion samples, a thermal model is applied in the current study to predict the dimensions of the melted zones and the heat-affected areas. Furthermore, the results obtained through the simulations are discussed and compared to the experimental data, thereby establishing the validity of the process models. Finally, the experimental studies also include the evaluation of the material hardness and residual stresses after laser polishing.

Laser processing technologies for micro-/nanostructuring of electrode materials have a great potential in improving the electrochemical performance and operational lifetime of lithium-ion cells. Different types of laser structuring were used on different surfaces such as metallic current collectors and thin or thick film electrodes. For thin metallic current collector foils, at anode and cathode sides, the self-organized structuring by laser-induced periodical surface structures and laser interference methods were successfully applied for improving electrode film adhesion and cell impedance. For thin and thick film electrode layers direct laser ablation with structure sizes down to the micrometer range and high aspect ratios were found most powerful in order to create three-dimensional (3D) cell architectures with benefits regarding cell performance and a homogenous wetting of composite electrodes with liquid electrolyte. A huge impact of laser formed 3D batteries regarding capacity retention and cell lifetime at high charging and discharging rates was detected. The impact on diffusion kinetics of laser structured 3D electrodes was studied using classical methods such galvanostatic intermittent titration technique and cyclic voltammetry. A further improvement of 3D battery performance due to an operation in high potential regime and for advanced high energy silicon anode material was achieved by joining of laser structuring and thin-film passivation either of active particles before laser patterning or by passivating of complete 3D electrodes after laser processing. Finally, laser-induced breakdown spectroscopy will be presented as a powerful tool for elemental mapping of entire 2D and 3D electrodes. The impact of 3D architectures on lithium distribution and chemical degradation processes in 2D batteries was investigated and analyzed.

Laser processes for cutting, annealing, structuring, and printing of battery materials have a great potential in order to minimize the fabrication costs and to increase the electrochemical performance and operational lifetime of lithium-ion cells. Hereby, a broad range of applications can be covered such as micro-batteries, mobile applications, electric vehicles, and stand-alone electric energy storage devices. Cost-efficient nanosecond (ns)-laser cutting of electrodes was one of the first laser technologies which were successfully transferred to industrial high-energy battery production. A defined thermal impact can be useful in electrode manufacturing which was demonstrated by laser annealing of thin-film electrodes for adjusting of battery active crystalline phases or by laser-based drying of composite thick-film electrodes for high-energy batteries. Ultrafast or ns-laser direct structuring or printing of electrode materials is a rather new technical approach in order to realize three-dimensional (3D) electrode architectures. Three-dimensional electrode configurations lead to a better electrochemical performance in comparison to conventional 2D one, due to an increased active surface area, reduced mechanical tensions during electrochemical cycling, and an overall reduced cell impedance. Furthermore, it was shown that for thick-film composite electrodes an increase of electrolyte wetting could be achieved by introducing 3D micro-/nano-structures. Laser structuring can turn electrodes into superwicking. This has a positive impact regarding an increased battery lifetime and a reliable battery production. Finally, laser processes can be up-scaled in order to transfer the 3D battery concept to high-energy and high-power lithium-ion cells.