GeO2-SnCoC Composite Anode Material for Lithium-Ion Batteries

Current methods for extending the cycle life of volume-expanded anode materials for lithium-ion batteries mainly focus on development of nanosize three-dimensional structures and composite materials. We propose a novel anode material of GeO2-Sn30Co30C40 that is synthesized by high energy ball milling (SPEX). This material depends on the nanosized and composite concept, which combines the advantageous properties of Sn-Co-C (long cycle life) and GeO2 (high capacity). The composite anode shows a reversible capacity over 800 mAh/g with good capacity retention. Furthermore, the first-cycle Coulombic efficiency is 80%, much higher than the 34.6% obtained for pure GeO2. Pair distribution function measurements indicated the reversible reaction of GeO2 and SnO2, which is the key factor in the improved Coulombic efficiency. This reversibility can be explained by the catalytic role of Co3Ge2 phase, which facilities the conversion reactions of metal oxides and acts as an electronic conductive component for the composite anode.