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In‐depth analyses, including discharge behaviour, electrochemical impedance analysis, and for the first time, nonlinear frequency response analysis, are conducted on the ageing of negative electrodes with varying particle size distribution. The electrode‐resolved analysis is used to distinguish the kinetic and transport losses at the respective electrodes. For fine to medium‐sized particles at the negative electrode, ageing impacts are found more on the positive electrode: the impedance and nonlinear responses increase, suggesting that the charge transfer process at the positive electrode is worsened. Meanwhile, for coarse and broad negative particles, the impedance and nonlinear responses at negative electrodes decrease due to improved kinetics from micro‐cracking. The second harmonic reveals a change in the nature of the charge transfer during ageing: the charge transfer process at the positive electrode becomes asymmetric for fine and medium‐sized negative particles. Vice versa, the charge transfer process at the negative electrode becomes symmetric for coarse and broad negative particles. [ABSTRACT FROM AUTHOR]

This study presents an approach for targeted comminution of component mixtures within a wet-operated stirred media mill. In the first step, a general understanding of the interactions between individual components on the grinding result with mixtures could be gained with basic experiments and following our former research work. In particular, a protective effect of the coarser particles on the fines could be elucidated. These findings were used to develop a process for the production of a battery slurry containing fine ground silicon particles as well as dispersed carbon black and graphite particles. By a tailored sample preparation applying a combination of particle dissolution and separation, the particle size distributions of carbon black and graphite particles were analyzed separately within the produced battery slurries. Based on the selective particle size analysis, the slurry preparation could be transferred from a complex multistage batch process using a dissolver to a stirred media mill, which was finally operated in a continuous one-passage mode. The prepared slurries were subsequently further processed to silicon-rich anodes using a pilot scale coating and drying plant. Afterward, the produced anodes were electrochemically characterized in full cells. The cell results prove a comparable electrochemical behavior of anode coatings derived from a dissolver- or mill-based slurry production process. Therefore, we could demonstrate that it is possible to integrate the mixing process for the production of multicomponent slurries into the comminution process for the preparation of individual materials upstream. Even with nearly identical starting sizes of their feed materials, the targeted particle size distributions of the single components can be reached, taking into account the different material-dependent particle strengths and sequential addition of single components to the multicomponent comminution process. [ABSTRACT FROM AUTHOR]

This work reveals the impact of particle size distribution of spherical graphite active material on negative electrodes in lithium‐ion batteries. Basically all important performance parameters, i. e. charge/discharge characteristics, capacity, coulombic and energy efficiencies, cycling stability and C‐rate capability are shown to be affected by distribution shapes. A narrow distribution with smaller particles results in better cell performance than broader and coarser distributions. However, particle size reduction has a limitation as extremely small particles show negative effect in performance. More critically, independent of the particle size distribution, the existence of coarse particles are found to promote lithium plating, which lowers cell performance and threatens the safety of battery operation. Furthermore, impedance analysis and cycling stability show huge differences for different electrodes. Our study shows that a better understanding of the influence of particle size distribution is an important base to engineer electrodes with higher C‐rate capability, higher performance, and lower safety risk due to lithium plating. [ABSTRACT FROM AUTHOR]

Electrode manufacturing requires multiple process steps, e.g., dispersing and coating. In‐between these steps, intermediate products have to be transferred, stored, and handled. Especially for the development of new active materials or electrode formulations, the variety of parameters that need to be screened is enormous. In addition, these materials are initially tested in small batches, and it is not always possible to upscale the used processes. To evaluate the performance of different materials or differently processed materials, test cells are assembled. This usually requires manual work procedures, which are inherently sensitive to variations and untraceable errors. If the stochastic flaws are large enough, the effects of process variations are covered by these. It is therefore important to increase reproducibility in all process steps. Herein, new concepts for electrode production and automated sample preparation for highly reproducible production and more effective electrode development and screening of parameters are presented. A combined grinding and dispersion process for the production of silicon‐based anodes and an automated assembly system for efficient testing is presented. The processes are supported by methods of data mining to collect process data, ensure high reproducibility, and support research on new active materials. [ABSTRACT FROM AUTHOR]

Polydispersity, electrode-resolved analysis, electrochemical impedance spectroscopy, distribution of relaxation time, nonlinear frequency response analysis, electrochemistry, surface analysis Cover Feature: Revealing the Impact of Particle Size Distribution on Ageing of Lithium-Ion Batteries with Frequency Response Analysis (Batteries & Supercaps 10/2023) Keywords: polydispersity; electrode-resolved analysis; electrochemical impedance spectroscopy; distribution of relaxation time; nonlinear frequency response analysis; electrochemistry; surface analysis EN polydispersity electrode-resolved analysis electrochemical impedance spectroscopy distribution of relaxation time nonlinear frequency response analysis electrochemistry surface analysis 1 1 1 10/10/23 20231001 NES 231001 B The Cover Feature b shows the particle-size specific ageing in lithium-ion batteries and its detection with nonlinear and linear frequency response analysis methods. [Extracted from the article]

Electrode structural stability and mechanical integrity is of major importance regarding not only lithium-ion battery performance but also safety aspects. The goal of this study is to design a simulation procedure to reproduce the microstructural and mechanical properties of such lithium-ion battery electrodes. Taking into consideration the particulate state of these electrodes, a discrete element method (DEM) approach is proposed, which comprises a procedure to reproduce real electrode structures and the application of a proper contact model to capture the bulk mechanics. This is accomplished by considering particle interactions as well as the performance of the binder. Three different electrodes are manufactured with the aim of calibrating and validating the Hertzian-bond contact model. Experimental nanoindentation measurements prove to be in good agreement with the simulation outcome, concluding that the method constitutes a valuable physical and mechanical basis for further applications. [ABSTRACT FROM AUTHOR]

• Preparation of silicon-graphite composites via fluidized bed for lithium-ion anodes. • High capacity silicon-on-graphite composites with ≈600 mAh g−1. • Ethyl cellulose enables strong adhesion of silicon nanoparticles on graphite. • Pitch coating improves electrical conductivity and stability of composite particles. • Pitch coated composites retain >70% of specific capacity after 400 cycles. Composites consisting of graphite and silicon have been considered as potential high-capacity anode materials for the next-generation Li-ion batteries (LIBs). The synthesis method is critical for determining the microstructure, which is directly related to the material performance and the cost-efficiency for making commercial electrode materials. Herein, we report the fabrication of silicon-on-graphite (Si@Gr) composites by fluidized bed granulation (FBG) for the first time. The FBG process is shown to produce composite powders comprising a uniform layer of nano-sized Si particles lodged onto the surface of micron-sized graphite particles to possess a core-shell microstructure. Adopting a suitable binder during the FBG process enables a firm adhesion of the Si nanoparticles on graphite surface during subsequent carbon-coating, where the composite particles are coated with pitch and then carbonised to form a highly electronically conductive and mechanical stabilizing layer of amorphous carbon. These carbon-coated composites exhibit a high capacity reaching over 600 mAh g−1, high rate capability and illustrates the potential of long-cycle stability in Si@Gr || Li metal cells, showing more than 70% capacity retention after 400 charge-discharge cycles even without electrolyte optimization. Furthermore, a significantly improved cycling stability is found for the carbon-coated Si@Gr materials in LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM-622) || Si@Gr full-cells. [ABSTRACT FROM AUTHOR]