The present work investigates the suitability of impedance spectroscopy to characterize typical plastic encapsulation materials in electronic packaging. In a first approach, a commercially available epoxy mold compound (EMC) after processing to millimeters thick free-standing samples is studied. The use of free-standing samples avoids any influence of substrate/encapsulation interaction and enables the investigation of the intrinsic properties before and after harsh conditions of exposition in a Pressure Cooker Test (PCT). The change of properties of the mold material and the uptake of water is characterized with impedance spectroscopy in a 2-electrode design. Complementary material diagnostic (FTIR) confirms the results of the impedance spectroscopy. The free-standing mold failed dramatically and degraded under the conditions of the PCT due to embrittlement of the polymer and a fast water uptake. The study impressively demonstrates the (electrochemical) impedance spectroscopy as a powerful tool for qualifying and characterizing materials with extremely high impedance, such as plastic encapsulations.

Citric acid is an environmentally friendly and non-toxic chemical which forms barrier-like oxide films on AA 7075 during anodization. The passive behavior and the kinetic of the film formation is investigated in macro- and microelectrochemical experiments. Galvanostatic formed anodic oxide films are investigated by FT-IRRAS and SEM. The oxide films formed are dense and free of pores and mainly consist of Al2O3. The formation of insoluble aluminum citrates is excluded at the chosen pH, but a small fraction of citrate in the oxide film is evident and explained by Zn and Cu complexes, respectively, incorporated in the aluminum oxide layer.

Magnesium alloys are promising biodegradable implant materials due to their excellent biocompatibility and non-toxicity. However, their poor corrosion resistance limits their application in vivo. Plasma electrolytic oxidation (PEO) is a powerful technique to improve the corrosion resistance of magnesium alloys. In this study, we present the accelerated degradation of PEO-treated AZ31 samples using a fluid dynamic test. The samples were prepared using different concentrations of KOH as an electrolyte along with NaSiO3. The anodizing time and the biasing time were optimized to obtain the increased corrosion resistance. The analysis of the degraded samples using microscopy, SEM EDX measurements, and by calculating mass loss and corrosion rates showed a significant increase in the corrosion resistance after the polymer (Resomer© LG 855 S) coating was applied to the anodized samples. The results confirm (or convince) that PEO treatment is an effective way to improve the corrosion resistance of AZ31 magnesium alloy. The fluid dynamic test can be used as an accelerated degradation test for biodegradable alloys in simulated body fluids at a physiological temperature. The polymer coating further improves the corrosion resistance of the PEO-treated AZ31 samples.

Bonding with integrated reactive material systems enables joining of heterogeneous substrates at room temperature. The increasing diversity of electronic modules raises the demand for low temperature bonding processes for heat sensitive components. In this article, fundamental steps for the deposition of Pd/In multilayers from a single bath electrolyte are presented. It furthermore describes the deposition of Pd/Sn reactive multilayers for bonding application on ceramic substrates and introduces a new semi‐automated plating tool for Pd/Sn multilayers. The Pd/Sn multilayers can be deposited reproducible on silicon and ceramic substrates. While a bilayer period of 425 nm enables stable ignition and bonding of Si substrates, the bilayer period for ceramics has to be increased to 620 nm to compensate the higher heat dissipation into the substrate. By integrating 2.5–9 μm thick Sn compensation layers beneath the integrated reactive multilayer systems (iRMS) to smoothen the surface profile of the printed metallization and improved bonding processes with wedge compensation, a homogeneous bond along the whole interface can be achieved.

This paper deals with the separate electrochemical recovery of transition metals from battery black liquor. In a first approach, the authors investigated a model waste electrolyte mainly consisting of Cu, Co, Ni, and Mn in an acidic solvent, using citric acid as a complexing agent. An open porous Inconel® foam had been included as an electrode to benefit from the increased active surface area. Under the selected operation conditions, Cu was completely recovered, presenting almost 100% purity, while, in the case of Co, the purity was 96%, and a remanent concentration of about 1.2 g L−1 could still be determined.

Mechanical grinding creates mechanical as well as thermal stress in treated material and the so-called Beilby layer is formed. The present work investigates the influence of abrasive coarse grain size on the thickness and electrochemical behavior of the native oxide layer formed after the grinding process by using cyclovoltammetry. The difference in the native oxide layer thickness amounts to Delta d approximate to 0.5 nm under the surface conditions investigated. Additionally, an experimental design is introduced and tested, which allows the operando measuring of the temperature of the material during the grinding process. Estimates result in a thermal stress Delta sigma between 0.8 and 1.3 MPa depending on the chosen grinding parameters and influence the subsequently formed oxide layer thickness.

The future of mobility focusses on electric engines and their implementation in modern vehicles. Therefore, different energy storage systems, new engine concepts and innovative electronic solutions needs to be developed and characterized. Especially the usage of wide bandgap semiconductors, offers an increasing efficiency potential. Such kind of GaN or SiC semiconductors are working at high temperatures, frequencies and rising voltage levels up to 1000 V. Therefore, suitable electrical insulations are strictly necessary, thus will open new material challenges. Currently insulation is realized by embedding the semiconductors in electronic boards (PCB, ceramics) or cover them with polymers. Polymer cover-ing is the state-of-the-art and mainly transferred from common silicon electronics. These materials must withstand higher electrical fields under harshest environmental conditions. Especially, the influence of humidity on polymers and consequently the water uptake is a critical parameter for the protection of metal substrates, in case of corrosion inhibition. A better understanding of the degradation mechanisms and the implementation of state of health analyses is required. Only in this way, further miniaturized technical solutions with sufficient long-term stability can be developed. This work focusing on demonstration and discussion of suitable measurement methods to determine the water uptake of such polymers. Electrochemical Impedance Spectroscopy (EIS) was used on lab scale level. Degradation models were derived from these results and development possibilities for inline measurement methods were discussed.

Although tin and tin oxides have been considered very promising anode materials for future high-energy lithium-ion batteries due to high theoretical capacity and low cost, the development of commercial anodes falls short of expectations. This is due to several challenging issues related to a massive volume expansion during operation. Nanostructured electrodes can accommodate the volume expansion but typically suffer from cumbersome synthesis routes and associated problems regarding scalability and cost efficiency, preventing their commercialization. Herein, a facile, easily scalable, and highly cost-efficient fabrication route is proposed based on electroplating and subsequent electrolytic oxidation of tin, resulting in additive-free tin oxide anodes for lithium-ion batteries. The electrodes prepared accordingly exhibit excellent performance in terms of gravimetric and volumetric capacity as well as promising cycle life and rate capability, making them suitable for future high-energy lithium-ion batteries.

The present work investigates the passive film formation and properties on tin and tin solder alloys in weakly acidic nitrate solution by using conventional electrochemical methods as well as electrochemical impedance spectroscopy and Mott–Schottky analysis. It is observed that the influence of the main alloying elements, antimony and copper, positively influences the formation and properties of native oxide films on the respective alloys. If the oxide film is anodically formed, the process can be interpreted as a high‐field mechanism. In this case, antimony, as well as copper, increases the electron conductivity of the anodic formed layers analogous to the transparent conducting oxide layers (e.g., ATO layers).

Plasma electrolytic oxidation (PEO) in an alkaline silicate electrolyte containing nanosized sepiolite fibers was carried out on magnesium alloy AZ31. The mineral fibers were loaded with different corrosion inhibitors and incorporated in situ during the PEO treatment. The composition and microstructure of the PEO coatings were investigated by SEM. It was shown that the fibers are located on the surface as well as inside the “weak spots” of the coating, i.e., pores and discharge channels. The fixation of the particles is caused by sintering due to the heat developed during the PEO treatment. Investigations using electrochemical impedance spectroscopy and linear sweep voltammetry in 0.01 M NaCl solution confirmed an improvement of the corrosion protection. The use of the inhibitors shifts the critical pitting potential in the anodic direction. Regarding efficiency, cerium-loaded sepiolite showed the best behavior by shifting the pitting potential by +0.9 V.

The present work deals with the investigation of the incorporation of nanosized ceramic particles (sepiolite) into an oxide layer formed on magnesium alloy AZ31 by plasma electrolytic oxidation (PEO). The actual (true) surface area of the sepiolite particles was determined to be 300 m2 g- 1. The particles were exclusively electrostatically stabilized in the used electrolyte without visible sedimentation, at least over 27 days. Using a current controlled pulse regime, the particles are incorporated into the oxide layer simultaneously to the PEO process. The study clearly reveals that the movement and deposition of the particles is based on electrophoresis. Considering the measured mobility of the particles of mu approximate to 6 mu m cm V-1 s- 1 and a very low field strength in the electrolyte (0.4 V cm-1) the particles velocity was calculated to upsilon approximate to 2.4 mu m s-1. The mass of deposited sepiolite was estimated to approximately 1.2 mg cm-2 under the chosen conditions. The fixation of the deposited particles is caused by sintering due to the heat development of the plasma discharge events.

During formation of Li-ion batteries, a ‘natural’ solid electrolyte interphase (SEI) is formed at the anode side by decomposition products of the electrolyte. The properties of the SEI are extremely decisive for the overall battery properties, such as rate capability and cycling stability. However, the SEI formation consumes Li, leading to so called ‘formation losses’ that can make up to 15% of the theoretical energy density of the battery. Several approaches have been presented to overcome formation losses while preserving excellent overall battery properties. Particularly, electrochemical prelithiation and the application of artificial SEIs prior cell assembly are considered to effectively reduced formation losses while improving the interfacial charge transfer properties and increasing cycling stability. Herein, the authors present an innovative approach of applying a multifunctional artificial SEI on anode material powders via consecutive atomic layer deposition (ALD) cycles. As a model system, graphite powder has been chosen to be modified and characterized. The resulting electrodes show substantially improved electrochemical performance in half cells and full cells, regarding initial capacity loss, CE and cycling stability. Furthermore, model electrodes consisting of a single layer of graphite particles were manufactured, which exclude the effects of a typical composite electrode and therefore reveal the intrinsic properties of the active material. Using this approach, the interfacial kinetics and the rate capability are investigated comparatively between pristine and ALD coated electrodes, revealing the impact of the artificial SEI on the materials level.

Multiwalled carbon nanotubes (MWCNT) were electrophoretically deposited from an environmentally friendly aqueous solution on aluminium current collectors which were carbon coated by physical vapour deposition. The carbon coating proved to be stable under electrophoretic deposition (EPD) conditions up to EPD voltage of U = 50 V and avoided any undesirable oxidation of the aluminium during the deposition process. The kinetics of the deposition was described and could be easily controlled by the suspension concentration and the deposition time. The deposition rate at U = 50 V is about 0.03 mg cm(-2) min(-1). As anodic oxide formation could be prevented the electrical contact to the current collector was improved allowing the surface area to be increased by MWCNT to be used as a double-layer capacitor. The gravimetric capacitance obtained was about 8 F g(-1).

Silicon (Si) is considered the most promising anode material for next‐generation high‐energy lithium‐ion batteries. To enable the use of pure Si anodes, patterning is essential to reduce electrode degradation caused by volume changes during cycling. The authors herein report a facile and scalable Cu electrodeposition (Cu‐ECD) process to tailor the topography of Cu current collectors for the directed formation of columnar Si anodes by physical vapor deposition (PVD). ECD parameters, such as Cu concentration, temperature, potential, and deposited amount of Cu, are systematically varied. The most promising ECD parameters are applied to modify commercial Cu foils, which are then used to prepare columnar Si anodes via PVD. Modified current collectors and resulting Si anodes are investigated by scanning electron microscopy (SEM), laser scanning confocal microscopy, and adhesion tests. Selected Si anodes are characterized in battery cells regarding cycling stability. It is shown that the adjustment of the current collector topography results in a significant increase in cycling stability. SEM analysis revealed differences in the mechanical degradation and electrochemical capacity decay. Based on the results, process–structure–property relationships between the topography of the Cu‐ECD current collectors, the resulting columnar Si anodes and their electrochemical performance are derived.

Zero-excess Li metal batteries (ZELMB), in which the Li-metal anode is plated in situ on the anode current collector during initial charging, have received considerable attention in recent years. Such batteries hold enormous potential for increasing energy density and simplifying battery production, thus reducing costs, material, and energy requirements. However, transfer into application has so far been limited by challenges related to the non-uniform deposition behavior of lithium, which leads to inadequate performance and safety concerns. To meet these challenges, the electrochemical deposition behavior of lithium must be very well understood to derive and evaluate knowledge-based optimization approaches. For this purpose, advanced characterization methods are urgently needed. Herein the use of operando electrochemical dilatometry (OED) to study Li deposition and dissolution in ZELMB is demonstrated. We show how OED not only provides information on thickness changes during Li deposition and stripping, but also allows insights regarding morphology evolution and quantification of dead Li. The present work is intended to serve as an example to demonstrate the valuable insights that can be gained with OED and to encourage the scientific community to use it to support the development of advanced Li-, Na-, or K-metal batteries.

The effective use of energy from sustainable sources is considered a crucial step on the way to a CO2-neutral economy. Low-grade waste heat (<100 °C) is widely and ubiquitously available, but difficult to convert into electrical energy with current technologies. Here, we demonstrate an electrochemical cell capable of directly converting ambient temperature fluctuations into electricity. Based on intercalation reactions with different entropies, any temperature change leads to a cell voltage and electrical energy can be extracted. The new cell concept features the advantages of thermo-electrochemical cells and pyroelectric-like energy harvesting, which opens a wide range of possibilities for effective and sustainable use of low-grade waste heat.

Plasma electrolytic Polishing (PeP) is an innovative surface treatment to produce smooth, high-gloss surfaces. It is a thermo-chemical process but often described as a special case of anodic dissolution. PeP is determined by an interplay between plasma chemical, thermochemical, and electrochemical processes. The mechanism is not yet fully understood and part of ongoing research. The planar plasma discharge renders direct observation of the interface extremely difficult. Specially developed flow cells could overcome current experimental limitations. The study investigates phenomena during process initiation, as vapor layer creation and current and temperature signals, using high-speed and thermal imaging to foster understanding and derive optimization strategies.

The presentation gives an insight into the fascinating world of anodizing as corrosion protection but also goes far beyond. Starting with an introduction to the formation of anodic oxide films and their characteristic features, the authors briefly outline the subject of pore nucleation and growth. The number, size, and shape of the pores essentially determine the properties and play a crucial role in the final application of the anodizing layers. The tailoring of pore design, considering the final application as well as the use of the porous oxide layers for subsequent functional modifications, is demonstrated by examples, exclusively developed in the working groups of the respective authors or in joint research projects, which were in part professionally accompanied and supported by the German Corrosion Society GfKORR e.V.

The use of electrodes with multiple active materials is considered a promising approach to develop advanced Li-ion batteries. Recent studies even point to synergistic effects in terms of rate performance. However, the origin of synergistic effects is still insufficiently understood to enable targeted material and design development and to optimize batteries accordingly. Using straightforward equivalent circuit modeling combined with electrochemical studies, we reveal that improvements in rate capability are an intrinsic property of blended electrodes. The electrical parallel connection of the components in the composite electrode allows the applied current to be distributed among the components in a way that the voltage losses become minimal. This way, rate-limiting components can still contribute to the electrode's capacity at high loads, which makes blended electrodes particularly attractive, e.g., for applications that must be able to handle high pulse loads. Based on the results, rational design principle are derived by means of a systematic sensitivity analysis, quantifying the influence of the individual active material properties. These findings greatly contribute to the understanding of the internal dynamics and synergy effects in blended electrodes and support the targeted development of advantageous material combinations and electrode designs for future Li-ion batteries.