Ing. Zbyněk Plachý

The significant deployment of lithium-ion batteries (LIBs) within a wide application field covering small consumer electronics, light and heavy means of transport, such as e-bikes, e-scooters, and electric vehicles (EVs), or energy storage stationary systems will inevitably lead to generating notable amounts of spent batteries in the coming years. Considering the environmental perspective, material resource sustainability, and terms of the circular economy, recycling represents a highly prospective strategy for LIB end-of-life (EOL) management. In contrast with traditional, large-scale, implemented recycling methods, such as pyrometallurgy or hydrometallurgy, direct recycling technology constitutes a promising solution for LIB EOL treatment with outstanding environmental benefits, including reduction of energy consumption and emission footprint, and weighty economic viability. This work comprehensively assesses the limitations and challenges of state-of-the-art, implemented direct recycling methods for spent LIB cathode and anode material treatment. The introduced approaches include solid-state sintering, electrochemical relithiation in organic and aqueous electrolytes, and ionothermal, solution, and eutectic relithiation methods. Since most direct recycling techniques are still being developed and implemented primarily on a laboratory scale, this review identifies and discusses potential areas for optimization to facilitate forthcoming large-scale industrial implementation.

This work is devoted to investigating the effect of flux residues on the underfill. Prepared samples were made of copper sheets to eliminate the influence of multi-layered, inhomogeneous materials. Two sets of these samples were designed for this work; where one set was cleaned in an isopropyl alcohol bath in an ultrasonic cleaner, and the other was left uncleaned to highlight the presence of flux. Underfill was applied to both sets of samples, and the assemblies created in this way were subjected to several diagnostic methods. The work results showed that even when no-clean flux was used, its residues remained on the base substrates, contaminating the underfill or preventing it from completely filling the gap. The ultrasonic cleaner proved to be a suitable method for cleaning the samples, thus, eliminating the influence of flux residues or other impurities on the underfill. Furthermore, mechanical tests indicated that non-cleaned samples are characterized by a greater dispersion in mechanical properties than cleaned ones. Therefore, eliminating the influence of the flux will allow us to achieve more accurate results in the underfill's effect on the reliability of the assembly, which will allow a better potential comparison of different methods of underfill application and other materials.

Environmental concerns push for a reduction in greenhouse gas emissions and technologies with a low carbon footprint. In the transportation sector, this drives the transition toward electric vehicles (EVs), which are nowadays mainly based on lithium-ion batteries (LIBs). As the number of produced EVs is rapidly growing, a large amount of waste batteries is expected in the future. Recycling seems to be one of the most promising end-of-life (EOL) methods; it reduces raw material consumption in battery production and the environmental burden. Thus, this work introduces a comprehensive pre-recycling material characterization of waste nickel-manganese-cobalt (NMC) LIB cells from a fully electric battery electric vehicle (BEV), which represents a basis for cost-effective and environmentally friendly recycling focusing on the efficiency of the implemented technique. The composition of the NCM 622 battery cell was determined; it included a LiNi0.6Co0.2Mn0.2O2 spinel on a 15 μm Al-based current collector (cathode), a graphite layer on 60 μm copper foil (anode), 25 μm PE/PVDF polymer separator, and a LiPF6 salt electrolyte with a 1:3 ratio in primary solvents DMC and DEC. The performed research was based on a series of X-ray, infrared (IR) measurements, gas chromatography–mass spectrometry (GC-MS), and inductively coupled plasma–optical emission spectrometry (ICP-OES) characterization of an aqueous solution with dissolved electrolytes. These results will be used in subsequent works devoted to optimizing the most suitable recycling technique considering the environmental and economic perspectives.

The popularity of lithium-ion batteries (LIBs) as crucial power sources has increased in recent years. LIBs represent a perspective technology for recycling because they comprise a high portion of valuable metals, such as nickel, manganese, cobalt, or lithium, and other metals, including aluminium, copper, and iron. Battery discharging represents an essential step in end-of-life (EOL) pretreatment, as it reduces the risk of fire or explosion in further processing. As a simple, quick, and inexpensive technique, an electrochemical discharging process via salt-based solutions is preferred for cylindrical cells. Nevertheless, it is necessary to consider the composition of obtained waste products and the possible environmental risks leading to their safe and non-hazardous EOL processing. This work evaluated discharging efficiency and environmental perspective for cylindrical LIB cells, which were treated using NaCl solution. All battery cells were discharged to the safe voltage limit (0.75 V) within 24 hours. Major organic components, including volatile solvents with high toxic hazards, such as carbonic acid esters, methyl salicylate, and propanoic acid esters, were identified in the waste solutions using gas chromatography with mass spectrometry (GC-MS). Moreover, the metal proportion in the solution was determined using inductively coupled plasma - optical emission spectrometry (ICP-OES) analysis; it is recommended to recover metals from the wastewater before EOL or cleaning treatment.

The wetting balance method is used for the precise classification of solderability of chosen substrates by solder alloys. This work deals with a weakness of the wetting balance method during the wettability measurement of connectors with the wetting issue. The wetting issues at examined pins connector appeared during the serial manufacturing production, and therefore, the connector pins were analysed using the wetting balance method. The wetting balance method showed a good wetting of the connector pins. The wetted pins were examined by scanning electron microscopy (SEM) to find the reason for the wetting issue. This analysis showed a non-wetted area at pins edges. Following investigation of pins microsections using confocal/optical microscopy showed the reason for the wetting issue, when the surface finish was much thinner or was missing on the edges of the pin. This was the reason for the wetting issue of the connector pins in serial manufacturing, even though the wetting balance test showed good wettability results because most parts of the pin surface had good wetting.

Humidity is an essential and integral part of human life, of which electrical equipment and devices are already an integral part. The moisture problem is mainly associated with components in non-hermetic plastic packages. Understanding the behavior of these components is a basic prerequisite for proper handling during the manufacturing process. By proper handling of the components, various moisture-related defects can be avoided. For these reasons, moisture sensitive devices (MSD) are divided into different moisture sensitivity levels (MSL), which indicate their floor life. The main danger associated with moisture does not lie in its absorption itself, but in the mechanical stress caused by the rapid expansion of the evaporated water in a relatively short time during the reflow soldering process. Defects associated with delamination and cracks of the component packages are one of the most common defects in surface mounting technology. If the absorbed moisture does not cause mechanical defects during production within the Surface Mount Technology (SMT), it can further accelerate the degradation phenomena of the device. The results of this work clearly show that components exposed to environments with higher relative humidity (RH) absorb more moisture than the same components at lower RH. By reducing RH, the risk associated with defects caused by mishandling MSDs can also be reduced.