In Situ Growth of W₂C/WS₂ with Carbon-Nanotube Networks for Lithium-Ion Storage

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Tungsten carbide (W2C) and tungsten disulfide (WS2) alloys show promise as anode materials for lithium-ion batteries due to W2C's high conductivity.
• However, W2C/WS2 nanoflower structures exhibit unstable performance linked to poor inter-leaf contact.

Purpose of the Study:

• To investigate the use of carbon nanotubes (CNTs) as conductive networks for in situ growth of W2C/WS2 alloys.
• To enhance the structural stability and electrochemical performance of W2C/WS2 anode materials for lithium-ion batteries.

Main Methods:

• In situ growth of W2C/WS2 alloys on CNTs.
• Characterization using X-ray diffraction (XRD) and scanning/transmission electron microscopy (SEM/TEM).
• Electrochemical performance testing, including cyclic voltammetry and impedance spectroscopy.

Main Results:

• CNTs influenced alloy growth, promoting a stacked layer structure with a ~7.2 Å lattice spacing, facilitating lithium-ion insertion/desertion.
• The CNT-modified anode (WCNT01) achieved a stable capacity of ~650 mAh g-1 after 100 cycles, outperforming the bare alloy (~300 mAh g-1).
• Impedance analysis revealed a 50-fold increase in lithium-ion diffusion coefficient in the CNT-enhanced anode compared to the bare nanoflowers.

Conclusions:

• CNTs effectively create conductive networks, improving lithium-ion transport and cyclic stability in W2C/WS2 alloy anodes.
• The in situ growth strategy using small quantities of CNTs is highly effective for optimizing metal-sulfide-based lithium-ion battery performance.