Display omitted
Calendering is the common compaction process for lithium-ion battery electrodes and has a substantial impact on the pore structure and therefore the electrochemical performance of ...Lithium-ion battery cells. For a targeted determination of the performance-optimized pore structure, it is of decisive importance to be able to comprehensively control the compaction process. Thus, during continuous calendering of graphite anodes and lithium nickel cobalt manganese oxide (NCM) cathodes the applied line load is tracked and varied at different speeds to compact the electrode to several coating densities. The generated pore structures are measured via mercury intrusion, resulting in quite similar porosities, while the densities of graphite and NCM diverge greatly. The porosities, measured via mercury intrusion, are compared to geometrical determined data, identifying compaction resistant closed pores in the NCM. On the basis of the measured porosity reduction the compaction behavior of the line load was found to be describable by an exponential model equation. The model parameters quantify the different compaction resistances of the cathodes and anodes in converging to a maximal density, respectively minimal porosity. This substantial difference could be traced to the closer packing of the spherical and harder NCM particles. The calendering speed showed only an insignificant impact up to speeds of 5m/min.
Lithium-ion batteries will play a crucial role in the development of mobile consumer devices, stationary energy storage systems, and electric mobility. The growth in these fields will bring about a ...surge in the lithium-ion battery market. This leads experts to agree that more effective recycling processes are needed in conjunction with the recycling of lithium. This calls for an entirely revolutionary recycling process which we here have attempted to develop.
Our approach uses thermal decomposition of the polyvinylidene fluoride binder to lessen the cohesion of coated active material particles and weaken the adhesion between coating and foil. Then, an air-jet-separator is able to detach the coating powder from the current collector foils while stressing remaining particulate agglomerates. This separation process named ANVIIL (Adhesion Neutralization via Incineration and Impact Liberation) was tested on a laboratory scale with electrode rejects. We compared this to the widely used mechanical recycling process that utilizes a cutting mill to separate the current collector and coating. Intermediates and products were characterized using thermogravimetric analysis, tape adhesion tests, atomic absorption spectroscopy, particle size analysis, and gravimetric sieve analysis. We found that 97.1% w/w of the electrode coating can be regained with aluminum impurities of only 0.1% w/w, 30 times purer than the comparative process. This demonstrates a more effective recycling process than is currently available that also enables the recapture of lithium from the electrode coating.
Display omitted
•A new process to recycle lithium-ion batteries is proposed.•The binder is thermally decomposed to weaken the adhesion of electrode coatings.•An air-jet-separator detaches coating powder from current collector foils.•Binder decomposition and impacts produce primary particles instead of agglomerates.•97% w/w of the coating can be regained with aluminum impurities of only 0.1% w/w.
Commercialization of solid‐state batteries requires the upscaling of the material syntheses as well as the mixing of electrode composites containing the solid electrolyte, cathode active materials, ...binders, and conductive additives. Inspired by recent literature about the tremendous influence of the employed milling and dispersing procedure on the resulting ionic transport properties of solid ionic conductors and the general performance of all solid‐state batteries, in this review, the underlying physical and mechanochemical processes that influence this processing are discussed. By discussing and combining the theoretical backgrounds of mechanical milling with regard to mechanochemical synthesis and dispersing of particles together with a wide range of examples, a better understanding of the critical parameters attached to mechanical milling of solid electrolytes and solid‐state battery components is provided.
Mechanochemistry offers promising possibilities regarding the scalability of solid‐electrolyte syntheses, cathode composite processing, and the mixing of materials for solid state batteries. This review addresses the theoretical background of mechanical milling, resulting in best practice advice, and providing insight into the beneficial and detrimental effects of milling on different material classes.
The fast charging capability of lithium-ion batteries is mainly constricted by mass transport limitations within the electrolyte that fills the porous network of the electrodes. The onset of a ...parasitic side reaction referred to as lithium plating strongly depends on the micro-structure of the batteries’ anode. In this study, a methodology is introduced that allows to investigate the influence of the slurry preparation on electrode properties and the resulting fast charging performance of graphite anodes. Therefore, an in-situ lithium plating detection technique based on the differential charging voltage is used to connect electrode properties with the fast charging capability of the anodes in lithium-ion cells. Following this approach, changes in the particle size distribution due to a high intensity mixing process using pilot-plant scaled planetary mixers are linked to a modification of the pore size distribution and the electrode tortuosity. Eventually, a deteriorated fast charging performance is connected to the increased tortuosity caused by high intensity mixing.
•Method to understand process-structure-property relationship for slurry mixing.•Relationship between anode porosity and onset of lithium plating.•High intensity slurry mixing results in abrasion of graphite particles.•Altered particle size and morphology result in diffusion-impeding pore structure.•Onset of lithium plating correlates with impedance-derived anode tortuosity.
Calendering is a key process step in the production chain of lithium ion battery electrodes since it strongly affects the microstructure and micromechanics of the electrodes and hence, the ...performance and life of the battery. A comprehensive understanding is therefore necessary to find optimal levels of calendering which can help to enhance conductive and mechanical properties. Within this context, this study proposes a novel discrete element method (DEM) approach which can capture the mechanical properties of single Li Ni1/3 Mn1/3 Co1/3O2 (NMC) particles with an appropriate elasto-plastic contact model, as well as the mechanical behavior of the additive-binder matrix via an additional bond model 1. With the support of real produced cathodes, the simulations were able to reproduce the calendering process while providing detailed information about the changes in electrode structural and mechanical parameters. In particular, the investigated features comprise the electrode porosity and thickness along with the specific free surface area, the contact area between NMC particles and current collector, the coordination number of NMC particles, the number of broken bonds and the directionality of the contacts together with the generated stress within the electrode. Moreover, the simulations are able to capture the viscoelastic response of the electrode, showing that the relative elastic recovery can be almost up to 17%, an important piece of information that cannot be obtained experimentally to date. Having established the fundamentals and simulation feedback, an upcoming publication is meant to complete this research by providing a numerical overview of the relations between the electrode structure and its properties affected by the calendering process and during the first electrochemical cycles.
Display omitted
•Study of the lithium-ion battery electrode response along the calendering process.•DEM elasto-plastic contact model combined with a bond model is calibrated and validated.•Elastic recovery varies from around 10.25% up to almost 17%, depending on the calendering degree.•Feasibility to fully characterize the microstructural and micromechanical evolution.
The global use of lithium-ion batteries of all types has been increasing at a rapid pace for many years. In order to achieve the goal of an economical and sustainable battery industry, the recycling ...and recirculation of materials is a central element on this path. As the achievement of high 95% recovery rates demanded by the European Union for some metals from today’s lithium ion batteries is already very challenging, the question arises of how the process chains and safety of battery recycling as well as the achievement of closed material cycles are affected by the new lithium battery generations, which are supposed to enter the market in the next 5 to 10 years. Based on a survey of the potential development of battery technology in the next years, where a diversification between high-performance and cost-efficient batteries is expected, and today’s knowledge on recycling, the challenges and chances of the new battery generations regarding the development of recycling processes, hazards in battery dismantling and recycling, as well as establishing a circular economy are discussed. It becomes clear that the diversification and new developments demand a proper separation of battery types before recycling, for example by a transnational network of dismantling and sorting locations, and flexible and high sophisticated recycling processes with case-wise higher safety standards than today. Moreover, for the low-cost batteries, recycling of the batteries becomes economically unattractive, so legal stipulations become important. However, in general, it must be still secured that closing the material cycle for all battery types with suitable processes is achieved to secure the supply of raw materials and also to further advance new developments.
Different discontinuously and continuously working dispersing devices were investigated to determine their influence on the structural and electrochemical properties of electrodes made from ...commercial LiNi
1/3
Co
1/3
Mn
1/3
O
2
(NCM) cathode active material. A laboratory-scale dispersing device was compared with a discontinuously working laboratory kneader and a continuously working extruder, both using 50% less solvent than the dissolver process. Rheological, mechanical, structural, conductive, imaging, and electrochemical analyses (C-rate test, long-term cycling) were carried out. The dispersing method and time were found to have a considerable impact on the structure and electrochemical performance. The continuous extrusion process resulted in good performance with more than 20% higher specific capacity at elevated C-rates compared with the discontinuous process. This can be attributed to better deagglomeration of the carbon black in the slurries, also resulting in 60% higher electrode conductivity. On top of these positive results, the changes in the drying step due to the reduced solvent use led to a 50% decrease in the time required for the constant-drying-rate period. The continuously working extrusion process was found to be most suitable for large-scale, cost-efficient, environmentally friendly production of slurries for lithium-ion battery electrodes.
Battery production has become an increasingly important issue for industry e.g. due to the advent of electric cars and the greening of grids. The battery production chain is very interdisciplinary ...and consists of many specialised, innovative processes and numerous influencing factors. In contrast to more established sectors, processes and their interactions are not well understood yet. Thus, this paper presents a data mining approach for predicting different quality parameters of battery cells based on extensive data acquisition over the whole process chain. The results can be used to improve the planning and control of battery production.
A method to determine the agglomerate and aggregate sizes of carbon black (CB), commonly used in anode and cathode suspensions for lithium-ion battery electrodes, is presented. An analysis via light ...diffraction and scattering was evaluated, and measuring parameters and the development of sample preparation are described in detail. Within this work, different dispersing additives were tested with regard to their ability to stabilize the CB agglomerates and aggregates after dispersing. Furthermore, a sample preparation routine was set up which enables the determination of CB particle sizes in about 10 min. This includes the separation of active material particles and the particle size analysis itself. Furthermore, the method was tested with discontinuously and continuously processed suspensions using a laboratory dissolver and a pilot-scale extruder. In these experiments, the progress of CB deagglomeration in the dispersing step could be proven. For this reason, the method represents a suitable instrument for a quality check in an early production stage.
Due to the ever-growing importance of rechargeable lithium-ion batteries, the development of electrode materials and their processing techniques remains a hot topic in academia and industry. Even the ...well-developed and widely utilized active materials present issues, such as surface reactivity, irreversible capacity in the first cycle, and ageing. Thus, there have been many efforts to modify the surface of active materials to enhance the electrochemical performance of the resulting electrodes and cells. Herein, we review the attempts to use polymer coatings on the anode active materials. This type of coating stands out because of the possibility of acting as an artificial solid electrolyte interphase (SEI), serving as an anode protective layer. We discuss the prominent examples of anodes with different mechanisms: intercalation (graphite and titanium oxides), alloy (silicon, tin, and germanium), and conversion (transition metal oxides) anodes. Finally, we give our perspective on the future developments in this field.
PDF
