Carbon nanotube–grafted silicon–carbon composite as a highly durable anode material for lithium-ion batteries

Abstract

Si has emerged as a promising anode material for next-generation Li-ion batteries owing to its exceptionally high theoretical capacity of ~3597 mAh g−1. Nevertheless, the substantial volume changes occurring during lithiation and delithiation lead to mechanical degradation and poor cycle stability, hindering its practical application. In this work, we synthesized a Si–C composite incorporating single-walled carbon nanotubes (SWCNTs) via a simple and green microemulsion route. This approach enables the homogeneous distribution of Si nanoparticles and SWCNTs within a carbon matrix derived from corn starch, thereby improving the structural integrity of the resulting Si@C@CNT composite and suppressing particle pulverization. The well-dispersed SWCNTs not only reinforce the mechanical robustness of the composite but also establish a conductive network that sustains electrical connectivity in high mass loading electrodes. This design effectively mitigates the intrinsic drawbacks of Si, such as poor conductivity and volume expansion, resulting in an areal capacity of 3.20 mAh cm−2 in half-cell configurations and a capacity retention of 85% after 100 cycles. Moreover, the Si@C@CNT composite exhibits a stable cycling performance in a pouch-type full-cell featuring a Si@C@CNT/graphite blended anode and an NCM811 cathode, demonstrating strong potential for practical applications.