Impact of Temperature on the Diffusion in Silicon-Based Anodes

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Kems4Bats, established within the BMBF framework NanoMatFutur at Hochschule Mannheim, focuses on understanding heat and gas evolution in Li-ion batteries through advanced experimental methods. The group integrates thermodynamic data and new insights into phenomena like diffusion, solid electrolyte interface formation, aging from high-power charging, and thermal runaway. A state-of-the-art laboratory with cutting-edge equipment allows detailed study of materials properties affecting diffusion coefficients and heat and gas evolution, such as electrode composition and particle size. Key achievements include setting up a battery production line and developing a novel device, KEMS (Knudsen-Effusion Mass-Spectrometry), for vapor pressure measurements, enhancing battery safety and performance.Building on the experimental capabilities and insights gained by the Kems4Bats group, our research also zeroes in on specific materials that hold promise for enhancing battery performance. Among these, silicon stands out due to its high theoretical capacity, making it an ideal candidate for the next generation of anode materials in lithium-ion batteries. However, despite its potential, certain thermodynamic properties of silicon remain inadequately explored, notably diffusion. Diffusion is crucial as it facilitates the transport of ions to the active material's surface, essential for lithiation. This process is influenced by various factors including the state of charge (SOC) and cell temperature.This study explores the impact of temperature on the diffusion coefficient of self-made silicon anodes, composed of nanoparticles mixed with carbon black. The weight ratio between the anode components is 45/45/10 (Si/CB/CMC). PAT-Cells are used to assemble half-cells with a lithium-counter electrode. The half-cells, organized into four groups of at least three cells each, are examined at different temperatures (15°C, 25°C, 40°C, and 60°C) post-formation. The diffusion coefficient is determined via the galvanostatic incremental titration technique (GITT). Furthermore, incremental capacity analysis (ICA) is conducted to determine the impact of phase changes in the active material on the coefficient and to show the impact of temperature on the anodes' capacity.In summary, our investigation provides crucial insights into the temperature-dependent behavior of the diffusion coefficient in silicon anodes, a key component for enhancing lithium-ion battery performance. By analyzing the effects of temperature on both the diffusion process and phase changes within silicon-carbon black composite anodes, this study underscores the significant influence of thermal conditions on the efficiency and capacity of next-generation battery technologies. These findings not only contribute to a deeper understanding of silicon anodes' operational dynamics but also highlight the critical role of temperature management in optimizing lithium-ion battery performance.