Elucidating the Role of Carbon Conductive Additive in the Processing and Electrochemical Behavior of Surface-Modified Si Anodes

Journal Article · 15 March 2024 · Energy and Fuels

DOI: https://doi.org/10.1021/acs.energyfuels.4c00039 · OSTI ID:2429847

Araño, Khryslyn G.  ^[1]; Armstrong, Beth L.  ^[1]; Yang, Guang  ^[1]; Kumara, Chanaka ^[1]; Ward, Thomas Zac  ^[1]; Meyer, Harry M. ^[1]; Rogers, Alexander M. ^[1]; Toups, Elena ^[1]; Veith, Gabriel M.  ^[1]

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1. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

In the present work, we explore the impact of conducting carbon on the processing of silicon (Si)-rich electrodes, their resulting cycling performance, and parasitic side reactions. We employed three different carbon additives, Super C45 (carbon black), Super C65 (carbon black), and TIMCAL C-NERGY KS 6L (graphite), with varying sizes and morphologies to determine how these parameters influence the structure and the electrochemical behavior of the cast electrodes. Raman mapping indicates that the improved performance achieved using C45 can be explained by the homogeneous distribution of Si and carbon, enabling the formation of continuous electrical pathways throughout the electrode. Further, this finding aligns with the results of ζ potential measurements, which indicate that C45 can maintain more stable dispersions in N-methyl-2-pyrrolidone (NMP) compared with the other carbon additives. However, electrodes with C45 as the conducting agent exhibited increased parasitic side reactions, as evidenced by the leakage current obtained from voltage hold experiments. These side reactions can have adverse effects on the calendar life of the electrode. Furthermore, the Raman maps of the electrodes reveal heterogeneities in Si and carbon distribution with lower carbon content, especially with only 2% carbon. This drastically impacts the cyclability of the electrodes, with portions of the low-carbon electrodes that remain unable to undergo cycling even at slow rates (0.2 Ah g^–1). Additionally, we found that slower formation rates are favored in the context of parasitic side reactions, although slower formation rates can potentially create thicker passivating films that could hinder Li⁺-ion transport. Therefore, we emphasize the need for an intricate balance in materials selection and cycling protocol for optimal electrode processing and electrochemical behavior.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Energy Frontier Research Centers (EFRC) (United States). Fast and Cooperative Ion Transport in Polymer-Based Materials (FaCT)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Office of Sustainable Transportation. Vehicle Technologies Office (VTO); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 2429847
• Journal Information: Energy and Fuels, Journal Name: Energy and Fuels Journal Issue: 7 Vol. 38; ISSN 0887-0624
• Publisher: American Chemical Society (ACS)Copyright Statement
• Country of Publication: United States
• Language: English