A Haloing Structured SiMPs@Cu Composite Anode Material for Lithium Ion Batteries

Micrometer sized silicon particles encapsulated in copper layer (SiMPs@Cu) was synthesized by a simple electroless deposition process. The pH values, copper salt concentrations and the complexing agent concentration were studied to evaluate the factors which affected the copper layer structures. The micro sized Si particles were uniformly surrounded by a layer of Cu nanoparticles which can construct a conductive network within the electrode. The final composite SiMP@Cu can be obtained after H2 treatment with a microstructure well maintained. The electrochemical properties of the composite were characterized in terms of Cyclic Voltammetry (CV), Gavanostatic charge/discharge (GCD) and Electrochemical Impedance spectroscopy (EIS). The SiMPs@Cu prepared  at pH5 and with a concentration of 0.32 M Cu salt and 0.1 M complexing agent exhibited a improved specific capacity of more than 500 mA/g (at a current density of 100 mA/g) after 200 cycles, which is much better than the SiMPs without copper deposition. The result demonstrates that the copper layer can effectively alleviate the failure issue of electrode induced by Si pulverization during the charge/discharge process. This method is cost-effective and easy-to-control which illuminates a feasible strategy to fabricate Si anode with cheap micro sized Si starting material.