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Page 2 of 12 Zhang et al. Energy Mater 2024;4:400043 https://dx.doi.org/10.20517/energymater.2023.102

INTRODUCTION
Lithium-ion batteries (LIBs) have become ubiquitous in portable electronic equipment, electric vehicles,
[1-3]
and smart grids . However, the slow advancement in their energy density poses a challenge to meeting the
demands of rapidly evolving energy storage applications. It is imperative to focus on developing advanced
anode materials to tackle this challenge, especially if enhancing existing cathode materials proves
[4,5]
difficult . The SiO (0 < x < 2) anode has several advantages. First, SiO has a high theoretical specific
x
x
-1
-1
capacity, such as ~1,900 mAh·g for SiO and ~2,700 mAh·g for SiO, facilitating the realization of high-
2
energy-density LIBs . Second, it is abundant and can be readily prepared on a large scale from agricultural
[6,7]
waste . Lastly, SiO -based anodes generate Li O and Li silicate during cycling, ensuring greater cycling
[8]
x
2
stability than Si-based anode materials [9-10] . However, SiO experiences a volumetric change of 200% during
x
lithiation, leading to anode material breakdown and rapid capacity deterioration [11,12] . Furthermore, it
-4
exhibits low conductivity, approximately 6.7 × 10 S·cm , leading to poor rate capability. SiO -carbon
-1
x
composites have been proposed to mitigate these significant challenges. These composites demonstrate
promising electrochemical performance, leveraging the superior electronic conductivity and superior
mechanical properties of carbon materials [13-15] .
Carbon nanotubes (CNTs) are highly conductive and remarkably elastic. They are widely used to address
SiO -related challenges . However, given their one-dimensional (1D) nature, CNTs often require support
[16]
x
from other carbon materials when paired with SiO . Alternatively, two-dimensional (2D) graphene or three-
x
dimensional (3D) graphite are viable alternatives [17,18] . For example, SiO -graphite composites have been
x
recognized as encouraging candidates for high-performance LIBs, benefiting from enhanced capacity and
conductivity of graphite. Nevertheless, the unique alloying-intercalation mechanism inherent in SiO -
x
graphite anodes presents significant obstacles, including volume fluctuations and an unstable solid-
electrolyte interface. Graphene, derived from graphite, is an excellent support material for high-
performance SiO anodes in LIBs because it can mitigate volume changes, shorten lithium-ion transmission
x
pathways, and increase conductivity . However, differences in morphology between 0D SiO particles and
[19]
x
1D CNTs or 3D graphite/2D graphene pose challenges in achieving robust interface adhesion between SiO
x
and carbon. The weak interfacial interaction forces between SiO and carbon impede effective interfacial
x
electron transfer and structural stability within the carbon network. A potential solution is to establish
chemical bonds with active materials, thereby fostering a cohesive structure that enhances the high specific
capacity of SiO while preventing their displacement . Addressing this challenge entails creating a 3D
[20]
x
carbon network through chemical bonding, incorporating multiple carbon dimensions. However,
identifying a preparation strategy that is both scalable and highly efficient for this approach remains
challenging .
[21]
This study introduces a conductive dual-carbon network consisting of 1D CNTs and 3D graphite,
chemically bonded with SiO via C–O–Si linkages, facilitated by high-energy ball milling. This network was
x
devised to enhance the electrochemical capabilities of 0D SiO nanoparticles. The synergistic effect of CNTs
x
and graphite was shown through control groups wherein SiO was mixed solely with CNTs (SiO /C) or
x
x
graphite (SiO /G). Fourier transform infrared spectroscopy (FTIR) analyses confirmed the formation of
x
C–O–Si bonds, which agreed well with those results in X-ray photoelectron spectroscopy (XPS), validating
their role in improving the electrochemical properties of SiO /G/C electrodes. The dual-carbon network
x
enveloped SiO , reducing volume fluctuations and establishing efficient pathways for lithium transport.
x
Consequently, SiO supported by this dual-carbon interaction (SiO /G/C) exhibited enhanced cycling
x
x
performances and superior rate capability.