Regulating Single-Walled Carbon Nanotubes Network Formation in Thick Lithium-Ion Battery Electrodes by Evaporation-Moderated Drying

Abstract Reducing the fraction of inactive components is a direct strategy for increasing the energy density of lithium-ion batteries (LIBs). Single-walled carbon nanotubes (SWCNTs) are attractive conductive additives because their high aspect ratio enables the formation of a percolating network at low content. However, the low-solid-content slurries commonly used to process SWCNTs contain a large amount of solvent, which can lead to SWCNT migration and rebundling during drying. Here, we investigated how electrode loading and drying-induced redistribution affect the electrochemical effectiveness of SWCNT conductive networks in LiFePO4 (LFP) electrodes. At 12 mg cm–2, the SWCNT electrode exhibited the best rate capability and the highest contacted-particle fraction. However, at 24 mg cm–2, localized SWCNT bundling reduced the contacted-particle fraction, resulting in lower rate capability than the multiwalled carbon nanotube (MWCNT) electrode. Evaporation-moderated drying (EMD) reduced SWCNT migration and rebundling, restoring the contacted-particle fraction and improving high-rate electrochemical performance. These results highlight drying-induced nonuniform SWCNT distribution as a critical limitation of SWCNT-based thick electrodes and the importance of controlling solvent-removal kinetics for maintaining effective SWCNT conductive network in thick electrodes.