Zinc-Triazolate Metal-Organic Framework Assisted Synthesis of Germanium Nanoparticles Encapsulated in Nitrogen-Doped Carbon as Anode Materials for Lithium-Ion Batteries

Abstract

Germanium (Ge) is demonstrated to be prospective as a lithium-ion battery anode material, yet the cycling stability is undermined by substantial volume fluctuations, restricting its viability for practical applications. Here, we present a facile Zn-based metal−organic framework (MOF) engaged route to produce Ge nanoparticles in situ encapsulated in nitrogen-doped mesoporous carbon (denoted as Ge@N-C) as an anode material. This method uses a zinc-triazolate MOF (MET-6) and commercial GeO₂ as the hybrid carbon and Ge precursors. After a heating treatment, the Ge@N-C composite is readily obtained along with the simultaneous thermal decomposition of MET-6 and the reduction of GeO₂. Benefiting from the mesoporous structure and high electrical conductivity of N−C, along with the strong interaction between Ge and N−C, the obtained Ge@N-C electrode exhibits a significant reversible charge capacity of 1012.8 mAh g⁻¹ after 150 cycles at 0.1 A g⁻¹, and excellent rate capability. Furthermore, a reversible charge capacity of 521.1 mAh g⁻¹ can be maintained at 5.0 A g⁻¹ after 1000 cycles.