Phenolic Resin-Based Silicon/Carbon Composites Modified with Ultralow-Content Single-Walled Carbon Nanotubes via Liquid-Phase Mixing Method for Lithium-Ion Batteries

Abstract

Commercialization of silicon (Si) as an anode material in lithium-ion batteries (LIBs) is hindered by its low electrical conductivity and substantial volume change during lithiation-delithiation. A promising solution to address these issues lies in developing silicon/carbon (Si/C) composites. Herein, a liquid-phase mixing strategy is employed to combine nano-Si, phenolic resin (PF), and single-walled carbon nanotubes (SWCNTs, 0.05 wt %) with an optimal stirring speed of 3000 rpm, which ensures uniform dispersion of SWCNTs without inducing oxidation of the nano-Si. After a high-temperature carbonization, the 3000-Si/SWCNTs/carbon-5 composite (3000-SSC-5) is produced, features a unique structural configuration. In this composite, the PF-based hard carbon effectively encapsulates nano-Si, suppressing its volume expansion, while the SWCNTs form a conductive network that significantly enhances electrical conductivity. When tested as an anode of LIBs, the 3000-SSC-5 electrode exhibits excellent rate performance (1114 mAh g^–1 at 4 A g^–1), and outstanding cycling performance (884 mAh g^–1 after 250 cycles at 0.5 A g^–1). Furthermore, the full cell of 3000-SSC-5 // NCM811 achieves a capacity retention rate of 82.3% after 1000 cycles, highlighting its superior long-term stability. This paper demonstrates that the electrochemical properties of PF-based Si/C composites can be significantly enhanced through liquid-phase mixing with an ultralow content of SWCNTs. The unique composite configuration and excellent electrochemical performance underscore the promising potential of 3000-SSC-5 for commercial LIBs.