Facile simultaneous polymerization enabled in-situ confinement of size-tailored GeO2 nanocrystals in continuous S-Doped carbons for lithium storage

GeO 2 is a promising anode material for lithium ion batteries due to its high theoretical capacity (1126 mAh g −1 for reversibly storing 4.4 Li + ), and moderately low operating voltage (<1.5 V). Nevertheless, the fabrication of truly durable GeO 2 anode with satisfactory rate capability and cycling stability remains a big challenge because of its inherent low conductivity, and the large volume expansion upon charge-discharge that causes severe capacity fading. In this study, an innovative nanostructure with size-adjustable GeO 2 nanoparticles (16–26 nm) embedded in continuous S-doped carbon (GeO 2 /S-doped carbon, GSC) has been successfully fabricated via a facile in-situ simultaneous polymerization method followed by heat treatment. The electrochemical results indicate that the as-prepared GSC composites show high reversible capacity (672.9 mAh g −1  at 50 mA g −1 ), superior rate capability (332.9 mAh g −1  at 1000 mA g −1 ), and long-term cycle life (179 mAh g −1 after 500 cycles at 1000 mA g −1 ) as anode materials for lithium ion batteries. The excellent electrochemical performance of GSC nanocomposites could be ascribed to the homogeneous and continuous S-doped carbon matrix, which provides shortened ion diffusion pathway, increased electrical conductivity, enhanced structural stability, and introduced surface/interface property.