A novel composite negative electrode consist of multiphase Sn compounds and mesophase graphite powders for lithium ion batteries

A modified electroless plating technique was adopted to prepare the Sn compounds/mesophase graphite powders (MGP) composite electrode. Characterization of the composite material showed that multiphase Sn compounds were uniformly deposited on MGP. The multiphase composition which contained metallic Sn, SnP3 and SnP2O7 were expected to provide a higher spectator to Sn ratio for improved cycleability. During cycling between 0.001 and 1.5 V, the charge capacity was greatly enhanced without appreciable fading. From the voltage profiles and cyclic voltammetry (CV) curves, it was revealed that the capacity fading was caused by either the formation of insulated LiP in the early stage or by aggregation of metallic Sn after prolonged cycling. For improving the cycleability, the cut-off voltage was lowered from 1.5 to 0.9 V. Adjusting the voltage range was manifested to be an effective way for obtaining superior cycling performance in the Sn–P–O/MGP composite negative electrode. The capacity retention was as high as 96% of the highest capacity after charge/discharge between 0.001 and 0.9 V for 45 cycles.