Ionic liquid electrodeposition of germanium/carbon nanotube composite anode material for lithium ion batteries

• Ge/CNTs composite electrodes have been synthesized simply by ionic liquid electrodeposition.
• Ge nanoparticles with size about 20–50 nm were homogenously anchored on CNTs network.
• The as-prepared Ge/CNTs were used as anode materials for Li ion batteries without any binders.
• The as-prepared Ge/CNTs electrode shows excellent electrochemical performance.

Germanium nanoparticles (Ge-NPs) are combined with carbon nanotubes (CNTs) to fabricate anodes for Li-ion batteries through the electrodeposition of Ge from ionic liquids on the surface of the CNTs. The latter are electrophoretically deposited on a copper collector at room temperature without any binders, with a good electrical contact achieved nonetheless between the active material and the collector. In the composite, the CNTs readily accommodate the large volume changes of the Ge particles during cycling. The composite exhibits better reversible lithiation–delithiation behavior, an improved rate performance, and also has better electrochemical properties than Ge-NPs. The nanocomposite anode developed here delivers a reversible capacity of 810 mA h/g after 100 cycles at 0.2 C.