Evaluation of the electrochemical and expansion performances of the Sn-Si/graphite composite electrode for the industrial use

Abstract

The future development of lithium-ion battery in electric vehicles needs to improve its energy density, which is largely depends on the application of novel active materials with high specific capacity. Recently, Sn-Si hybrid materials have been proved to achieve both high specific capacity and good cycle stability. In practice, Sn-Si are mixed with graphite to form a composite electrode in order to further improve the stability. However, detailed investigation of the Sn-Si/graphite electrodes is seldom found. The current study examines the most concerned electrochemical and expansion performances of the Sn-Si/graphite anodes, accompanied with the morphology, crystalline and chemical composition analysis. The percolation model and the lattice expansion model are proven to fit well for the capacity and expansion evolution law of the composite anodes, respectively, as function of Sn-Si hybrid percentages. Base on the comparison with the conventional graphite anode, an efficient Sn-Si/graphite composite anode could be concluded that achieves a high reversible capacity (450 mAh g-1), a promising 1st coulombic efficiency (75%) and stable cycling (cycling coulombic efficiency > 98%), making it one of the Sn-based anodes closest to industrial use.