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 GeO 2 –Sn 30 Co 30 C 40 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 GeO 2 (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 GeO 2 . Pair distribution function measurements indicated the reversible reaction of GeO 2 and SnO 2, which is the key factor in the improved Coulombic efficiency. This reversibility can be explained by the catalytic role of Co 3 Ge 2 phase, which facilities the conversion reactions of metal oxides and acts as an electronic conductive component for the composite anode.