Realizing reversible conversion-alloying of GeO2/N-doped carbon nanocomposite with oxygen vacancies for lithium-ion batteries

A new nanocomposite of GeO2/nitrogen-doped carbon (GeO2/NC) with abundance oxygen vacancies has been synthesized based on a reaction induced by a cationic surfactant and not only exhibits a superb rate performance and favorable cycling stability but also displays an ultrahigh reversible capacity when served as an anode for lithium ion batteries. Such an excellent performance can be associated with the highly enhanced kinetics in conversion reaction, which is derived from the synergistic effects among the unique N-doped carbon layer, GeO2 nanoparticles, and oxygen vacancies. Driven by the overwhelming advantages, the GeO2/NC nanocomposite delivers a large capacity of 1044.6 mA h/g at 1.0 A/g even after 1200 cycles with negligible capacity attenuation and superb reversibility, in which a Coulombic efficiency is over 99.6%. Furthermore, the electrochemical reaction mechanism is also revealed by the in situ X-ray diffraction and ex situ X-ray photoelectron spectroscopy, and confirming that the conversion reaction is highly reversible even after 1200 cycles.