Preparation and characterization of a new nanosized silicon-nickel-graphite composite as anode material for lithium ion batteries

摘要

A new type of nanosized silicon-nickel-graphite (Si-Ni-G) composite was prepared by high energy mechanical milling (HEMM) and pyrolysis using SiO as the precursor of Si for the first time. X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM) and scanning electron microscopy (SEM) were used to determine the phases obtained and to observe the microstructure and distribution of the composite. The composite powders consisted of Si, Ni, SiO_2, NiO and a series of Si-Ni alloys. The formation of the inactive SiO_2 and Si-Ni alloy phases could accommodate the large volume changes of the active particles during cycling. In addition, cyclic voltammetry (CV) and galvanostatic discharge/charge tests were carried out to characterize the electrochemical properties of the composite. The composite electrodes exhibited an initial discharge and charge capacity of 1450.3 and 956.4 mAhg~(-1), respectively, maintaining a reversible capacity of above 900 mAhg~(-1) for nearly 60 cycles.