A novel textile-like carbon wrapping for high-performance silicon anodes in lithium-ion batteries

Abstract

Carbon coating is essential for active materials in electrochemical applications that are often insulators or poor conductors. A conventional conformal carbon coating can hinder the ion diffusion to and from the active material and form an isolated conducting network. Especially, active materials with very large volume expansion, e.g., silicon, can destroy the carbon coating during lithiation, which makes conformal carbon coating inappropriate. This paper presents a novel textile-like carbon wrapping that provides efficient electron and ion diffusion paths via a wide-range carbon network and pores. The textile-like carbon wrapping can reduce the electrical contact loss during cycling through the wide-range carbon network, which makes it a suitable carbon coating for materials that undergo volume expansion. A textile-like carbon-wrapped silicon is formed by pyrolysis of a dried suspension of silicon nanoparticles mixed with enzymatically hydrolyzed cellulose nanofibers. It shows excellent electrochemical performance compared to a conformal carbon-coated silicon. It exhibits a reversible specific capacity of 680 mA h g⁻¹ at 8.0 A g⁻¹ and shows excellent cycling stability (capacity retention of 94.5% after 500 cycles at 2.0 A g⁻¹) with high Si content (95.71 wt%). Therefore, this novel textile-like carbon wrapping can be utilized in many electrochemical applications instead of the conventional carbon coating, especially for active materials that undergo large volume expansion.