Microstructure Analysis and Performance of Wood Lignin-Derived Carbon Foam Electrodes for Sodium-Ion Batteries

Carbon foams (CF) offer a promising avenue for advancing energy storage systems due to their unique structure characterized by interconnected open-cell pores at both the nano and micro-scale [1], [2]. This structure provides tunability to the porosity, pore structure and size, which makes them ideal for high-energy dense electrodes for energy storage devices. Lignin-derived foams are particularly noteworthy as they utilize an abundant waste stream from paper products, offering a sustainable alternative to fossil-fuel-derived carbons often used in batteries. CFs can serve as electrodes or hosts for energy storage devices based on porosity, pore structure and size, and degree of graphitization, which significantly influences battery capacity, reversibility, and electrochemical reactions[3]. Utilizing natural CF from kraft lignin not only minimizes impacts compared to fossil-fuel-derived carbon sources[4] but also cuts production costs [2], making them an attractive option for large-scale energy storage systems.
In this investigation, we examined lignin-derived CFs with differing porosity and pore structures, carbonized across range of temperatures. A simple etching process is used to remove impurities and open clogged pores to increase reproducibility, rate capability, and reversible capacity. Pouch cells were assembled using a standard electrolyte, which demonstrated reversible capacities surpassing 300 mAh/g at C/10, with excellent cycling stability affirming the potential of lignin-derived CF-based Na-ion batteries for large-scale energy storage applications. The performance is studied as a function of CF microstructure, porosity, pore structure and size, particle size, and degree of graphitization for a fundamental understanding of the CF electrode. In conclusion, utilizing sodium and lignin, both abundant and low-cost materials, presents a promising avenue for the energy storage industry on a large scale.
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