A Ge/GeO2/Titanate nanocomposite with high energy density and enhanced long-term stability for lithium-ion batteries

Abstract

This study introduces a novel Ge/GeO₂/Titanate composite to address the limitations of conventional Ge-based anode materials, including volume expansion, particle aggregation, and unstable SEI formation during repeated charge–discharge cycles. By combining two-dimensional (2D) layered titanate nanosheets with Ge/GeO₂ nanoparticles, the composite achieves enhanced structural stability and outstanding electrochemical performance. The 2D titanate nanosheets effectively mitigate the volume expansion of Ge/GeO₂ nanoparticles, prevent particle aggregation, and maintain the long-term structural stability of the electrode while enhancing lithium-ion and electron transport pathways. Moreover, the thin amorphous GeO₂ layer on the Ge/GeO₂ nanoparticles suppresses excessive reactions with the electrolyte, promotes uniform and stable SEI formation, reduces irreversible capacity loss, and further contributes to the electrode's long-term stability. The Ge/GeO₂/Titanate composite exhibits exceptional performance, retaining a high capacity of 925.8 mAh/g (∼94 % of the theoretical capacity) after 350 cycles at 0.1 A/g. It also achieves capacity retention rates of 88.3 % and 73.4 % after 1200 charge–discharge cycles at high current densities of 2.0 A/g and 5.0 A/g, respectively.