Effective binding sufficiently-small SiO2 nanoparticles within carbon nanosheets framework enables a high-performing and durable anode for lithium-ion batteries

Abstract

Silica (SiO₂), with its high theoretical capacity and abundance, holds great potential as anode material for lithium-ion batteries (LIBs). However, its practical application is hindered by inherently low conductivity and significant volume change during cycling. In this work, we present a simple yet effective strategy to address these challenges by homogeneously binding high-density, ultra-small SiO₂ nanoparticles within a carbon nanosheet framework (denoted as SiO₂@CNS). In this design, densely packed sufficiently-small SiO₂ nanoparticles (about 6 nm) ensure high electrochemical reactivity, while the conductive and flexible CNS matrix facilitates rapid ion/electron transfer and buffers volume changes during cycling. As a result, the SiO₂@CNS anode delivers a remarkable capacity of 607.3 mA⸱h/g after 200 cycles at 0.1 A/g, superior rate capability (407.4 mA⸱h/g at 2 A/g) and outstanding durability, retaining 93.1% of its capacity after 2000 cycles at 1 A/g. In-situ transmission electron microscopy and ex-situ microscopic and spectroscopic analyses reveal moderate volume variation and exceptional structural stability during cycling, supported by the formation of a robust solid-electrolyte interphase that underpins its long-lasting performance. Full cells paired with commercial LiFePO₄ cathode exhibit outstanding rate and cycling performance. This work provides valuable insights into developing highly-efficient SiO₂-based anodes for high-performance LIBs.