Electrochemical Amorphization As a Method to Increase the Rate Capability of Crystalline Silicon Anodes for Lithium-Ion Batteries

Abstract

Anodes manufactured from macroporous silicon have been studied. Galvanostatic cycling tests in half-cells with Li counterelectrode in a regime of charging capacity limited to Q₁ = 1000 mAh/g showed that the inclusion of a modifying cycle with increased time of electrochemical lithiation into the testing schedule allowed the charge/discharge rate to be increased upon return to the initial regime. The results are interpreted in terms of a two-phase model with a sharp a-Li_xSi/c-Si interface. The insertion of a large amount of lithium during the modifying cycle leads to an increase in the thickness of an amorphous layer, within which the insertion and extraction of lithium in subsequent cycles proceed at a higher rate.