Enhancing Lithium-Ion Batteries with a 3D Conductive Network Silicon–Carbon Nanotube Composite Anode

Abstract

To meet the rising demand for energy storage, high-capacity Si anode-based lithium-ion batteries (LIBs) with extended cycle life and fast-charging capabilities are essential. However, Si anodes face challenges such as significant volume expansion and low electrical conductivity. This study synthesizes a porous spherical Si/Multi-Walled Carbon Nanotube (MWCNT)@C anode material via spray drying, combining Si nanoparticles, MWCNT dispersion, sucrose, and carboxymethyl cellulose (CMC). The MWCNT incorporation creates a robust 3D conductive network within the porous microspheres, enhancing Li⁺ diffusion and improving fast-charging/discharging performance. After 300 cycles at 1 A g^–1, the material achieved a discharge capacity of 536.6 mA h g^–1 with 80.5% capacity retention. Additionally, integrating a 3D network of Single-Walled Carbon Nanotubes (SWCNTs) further enhanced capacity retention in a binder-free, self-supporting electrode created through vacuum filtration. The Si/MWCNT@C//LiFePO₄ full cell exhibited an initial Coulombic efficiency (ICE) exceeding 80%, with a specific capacity of 72.4 mA h g^–1 and 79.8% capacity retention after 400 cycles at 1 A g^–1. This study offers a promising strategy for improving the performance and structural design of Si anodes.