Fabienne Huttner

Bio: Fabienne Huttner is an academic researcher from Braunschweig University of Technology. The author has contributed to research in topics: Materials science & Moisture. The author has an hindex of 2, co-authored 4 publications receiving 22 citations.

Increased Moisture Uptake of NCM622 Cathodes after Calendering due to Particle Breakage

Abstract: As moisture presents a critical contamination in lithium-ion batteries (LIBs), electrodes and separators need to be post-dried before cell assembly. The moisture adsorption, desorption and re-adsorption of electrodes during processing is strongly dependent on their material system, manufacturing route and microstructure. The microstructure, in turn, is significantly defined by the coating density, which is adjusted by calendering. As a consequence, the calendering step is expected to directly influence the moisture sorption behavior of electrodes. This is why the influence of different coating densities and structural properties on the moisture content of NCM622 cathodes was investigated in this study. For increasing density, an increasing moisture content was detected by Karl Fischer Titration and sorption measurements. SEM and BET analyses showed an increasing amount of NCM622 particle breakage, accompanied by a rising surface area. Hence, the increased moisture uptake of cathodes with higher density is mainly caused by a higher surface area, which results from particle cracking and breakage during calendering. Electrochemical analysis showed that the increased active surface area of cathodes with higher densities leads to a good performance during formation and at low C-rates. However, the reduced porosity impairs the ionic conductivity and causes capacity loss at higher C-rates.

Design of Vacuum Post-Drying Procedures for Electrodes of Lithium-Ion Batteries

Abstract: In order to reduce the residual moisture in lithium-ion batteries, electrodes and separators need to be post-dried prior to cell assembly. On an industrial scale, this is often conducted batch-wise in vacuum ovens for larger electrode and separator coils. Especially for electrodes, the corresponding post-drying parameters have to be carefully chosen to sufficiently reduce the moisture without damaging the sensitive microstructure. This requires a fundamental understanding of structural limitations as well as heat transfer and water mass transport in coils. The aim of this study is to establish a general understanding of the vacuum post-drying process of coils. Moreover, the targeted design of efficient, well-adjusted and application-oriented vacuum post-drying procedures for electrode coils on the basis of modelling is employed, while keeping the post-drying intensity as low as possible, in order to maintain the sensitive microstructure and to save time and costs. In this way, a comparatively short and moderate 2-phase vacuum post-drying procedure is successfully designed and practically applied. The results show that the designed procedure is able to significantly reduce the residual moisture of anode and cathode coils, even with greater electrode lengths and coating widths, without deteriorating the sensitive microstructure of the electrodes.

Investigation of Moisture Content, Structural and Electrochemical Properties of Nickel-Rich NCM Based Cathodes Processed at Ambient Atmosphere

Abstract: For batteries with high energy density and good fast-charge capability, NCM cathode active materials with ≥80 mol% nickel are promising due to their high specific capacities. Unfortunately, the increase in nickel content is accompanied by a high susceptibility to moisture. Therefore, nickel-rich NCM is coated or doped by the manufacturers to increase its stability. However, it is unclear if special requirements regarding ambient humidity must still be met during the whole production chain, or only after post-drying and during cell assembly. Therefore, the structure and properties of three different nickel-rich NCM active materials (one doped monocrystalline, two coated polycrystalline materials) processed at ambient atmosphere were investigated. At every process step, moisture content and microstructure were examined. Prior to cell assembly, two different post-drying procedures were applied and investigated. As validation, electrochemical tests were performed. Both polycrystalline cathodes demonstrated good physical and electrochemical properties, despite the ambient process atmosphere. Higher moisture reduction led to improved electrochemical performances at higher C-rates. Finally, a comparison between dry and normal atmosphere of the best performing material indicates that a production of high-quality nickel-rich electrodes at ambient atmosphere is possible if their exposure to moisture is short and well-designed post-drying techniques are applied.

From Materials to Cell: State-of-the-Art and Prospective Technologies for Lithium-Ion Battery Electrode Processing.

Abstract: Electrode processing plays an important role in advancing lithium-ion battery technologies and has a significant impact on cell energy density, manufacturing cost, and throughput. Compared to the extensive research on materials development, however, there has been much less effort in this area. In this Review, we outline each step in the electrode processing of lithium-ion batteries from materials to cell assembly, summarize the recent progress in individual steps, deconvolute the interplays between those steps, discuss the underlying constraints, and share some prospective technologies. This Review aims to provide an overview of the whole process in lithium-ion battery fabrication from powder to cell formation and bridge the gap between academic development and industrial manufacturing.

Challenges in Ecofriendly Battery Recycling and Closed Material Cycles: A Perspective on Future Lithium Battery Generations

Abstract: 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.