Enabling High Capacity and Durable Si Anodes Through Simultaneous Construction of CNTs Assembled Network Wrapping, Surface Co Decorating, and Conformal Carbon Coating

Abstract

Herein, this work demonstrates a simple structure engineering strategy to construct in situ grown carbon nanotubes (CNTs) assembled 3D network wrapping surface cobalt (Co) nanoparticles (NPs)-decorated and conformal carbon-coated irregular silicon (Si) NPs (Si NPs@CNT@Co) for achieving high and durable lithium storage performance. It simultaneously integrates CNTs assembled 3D network wrapping, surface Co decorating and conformal carbon coating into Si NPs. The findings confirm that these structural characteristics enable Si NPs@CNT@Co to achieve improved electrochemical kinetics (smaller charge transfer impedance and activation energy, and higher Li⁺ ion diffusion coefficient and electric conductivity) and structural durability (more stable LiF-rich solid electrolyte interphase (SEI) layer, and smaller electrode expansion ratio) over the pristine Si NPs and Si NPs@CNT counterparts. Consequently, Si NPs@CNT@Co shows excellent performance, with 1345.9, 928.7, and 409.1 mAh g⁻¹ after 550, 600, and 1200 cycles at 400, 1000, and 5000 mA g⁻¹, respectively. Moreover, this strategy demonstrates remarkable effect not only on Si NPs, but also on irregular micrometer Si particles (µm-Si). The as-prepared µm-Si@CNT@Co also exhibits significantly enhanced cycle stability and rate capability over the pure µm-Si counterpart. This work might offer references for preparing relatively low-cost, potentially practical, and high-performance Si-based anodes through simple and practical methods.